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|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
quant-ph/0609164 | Won-Ho Kye | Won-Ho Kye | Quantum Key Distribution with Screening and Analyzing | 3 pages,1 figure. Typos are fixed | null | null | null | quant-ph | null | We propose a quantum key distribution scheme by using screening angles and
analyzing detectors which enable to notice the presence of Eve who eavesdrops
the quantum channel, as the revised protocol of the recent quantum key
distribution [Phys. Rev. Lett. 95, 040501 (2005)]. We discuss the security of
the proposed quantum key distribution against various attacks including
impersonation attack and Trojan Horse attack.
| [
{
"version": "v1",
"created": "Thu, 21 Sep 2006 15:14:23 GMT"
},
{
"version": "v2",
"created": "Fri, 22 Sep 2006 12:16:07 GMT"
},
{
"version": "v3",
"created": "Wed, 4 Oct 2006 14:21:37 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Kye",
"Won-Ho",
""
]
]
|
quant-ph/0609165 | Francesco Ticozzi | Francesco Ticozzi and Lorenza Viola | Single-bit Feedback and Quantum Dynamical Decoupling | 12 pages, 2 figures | Physical Review A 74, 052328, 2006 | 10.1103/PhysRevA.74.052328 | null | quant-ph | null | Synthesizing an effective identity evolution in a target system subjected to
unwanted unitary or non-unitary dynamics is a fundamental task for both quantum
control and quantum information processing applications. Here, we investigate
how single-bit, discrete-time feedback capabilities may be exploited to enact
or to enhance quantum procedures for effectively suppressing unwanted dynamics
in a finite-dimensional open quantum system. An explicit characterization of
the joint unitary propagators correctable by a single-bit feedback strategy for
arbitrary evolution time is obtained. For a two-dimensional target system, we
show how by appropriately combining quantum feedback with dynamical decoupling
methods, concatenated feedback-decoupling schemes may be built, which can
operate under relaxed control assumptions and can outperform purely closed-loop
and open-loop protocols.
| [
{
"version": "v1",
"created": "Thu, 21 Sep 2006 16:54:02 GMT"
}
]
| 2010-12-08T00:00:00 | [
[
"Ticozzi",
"Francesco",
""
],
[
"Viola",
"Lorenza",
""
]
]
|
quant-ph/0609166 | Fr\'ed\'eric Dupuis | Fr\'ed\'eric Dupuis, Nicolas Gisin, Andr\'e Allan M\'ethot | No nonlocal box with uniform outputs is universal | 11 pages, 3 figures | null | null | null | quant-ph | null | We show that standard nonlocal boxes, also known as Popescu-Rohrlich
machines, are not sufficient to simulate any nonlocal correlations that do not
allow signalling. This was known in the multipartite scenario, but we extend
the result to the bipartite case. We then generalize this result further by
showing that no finite set containing any finite-output-alphabet nonlocal boxes
with uniform outputs can be a universal set for nonlocality.
| [
{
"version": "v1",
"created": "Thu, 21 Sep 2006 19:04:45 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Dupuis",
"Frédéric",
""
],
[
"Gisin",
"Nicolas",
""
],
[
"Méthot",
"André Allan",
""
]
]
|
quant-ph/0609167 | Masaki Owari | Masaki Owari, Samuel L. Braunstein, Kae Nemoto, Mio Murao | \epsilon-convertibility of entangled states and extension of Schmidt
rank in infinite-dimensional systems | 23page, the third version. small typos changed | Quantum Information and Computation, Vol. 8, No.1&2 (2008)
0030-0052 | null | null | quant-ph | null | By introducing the concept of $\epsilon$-convertibility, we extend Nielsen's
and Vidal's theorems to the entanglement transformation of infinite-dimensional
systems. Using an infinite-dimensional version of Vidal's theorem we derive a
new stochastic-LOCC (SLOCC) monotone which can be considered as an extension of
the Schmidt rank. We show that states with polynomially-damped Schmidt
coefficients belong to a higher rank of entanglement class in terms of SLOCC
convertibility. For the case of Hilbert spaces of countable, but infinite
dimensionality, we show that there are actually an uncountable number of
classes of pure non-interconvertible bipartite entangled states.
| [
{
"version": "v1",
"created": "Thu, 21 Sep 2006 19:19:56 GMT"
},
{
"version": "v2",
"created": "Fri, 22 Sep 2006 06:36:50 GMT"
},
{
"version": "v3",
"created": "Tue, 15 May 2007 03:55:57 GMT"
},
{
"version": "v4",
"created": "Wed, 3 Oct 2007 09:02:16 GMT"
}
]
| 2009-09-29T00:00:00 | [
[
"Owari",
"Masaki",
""
],
[
"Braunstein",
"Samuel L.",
""
],
[
"Nemoto",
"Kae",
""
],
[
"Murao",
"Mio",
""
]
]
|
quant-ph/0609168 | Andris Ambainis | Andris Ambainis | Quantum search with variable times | 19 pages | null | null | null | quant-ph | null | Since Grover's seminal work, quantum search has been studied in great detail.
In the usual search problem, we have a collection of n items and we would like
to find a marked item. We consider a new variant of this problem in which
evaluating the i-th item may take a different number of time steps for
different i.
Let t_i be the number of time steps required to evaluate the i-th item. If
the numbers t_i are known in advance, we give an algorithm that solves the
problem in O(\sqrt{t_1^2+t_2^2+...+t_n^2}) steps. This is optimal, as we also
show a matching lower bound. The case, when t_i are not known in advance, can
be solved with a polylogarithmic overhead. We also give an application of our
new search algorithm to computing read-once functions.
| [
{
"version": "v1",
"created": "Thu, 21 Sep 2006 21:38:29 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Ambainis",
"Andris",
""
]
]
|
quant-ph/0609169 | Yiyang Gong | Yiyang Gong, Jelena Vuckovic | Design of Plasmon Cavities for Solid-State Cavity QED Applications | added physical temperature dependence, added reference | null | 10.1063/1.2431450 | null | quant-ph physics.optics | null | Research on photonic cavities with low mode volume and high quality factor
garners much attention because of applications ranging from optoelectronics to
cavity quantum electrodynamics (QED). We propose a cavity based on surface
plasmon modes confined by metallic distributed Bragg reflectors. We analyze the
structure with Finite Difference Time Domain simulations and obtain modes with
quality factor 1000 (including losses from metals), reduced mode volume
relative to photonic crystal cavities, Purcell enhancements of hundreds, and
even the capability of enabling cavity QED strong coupling.
| [
{
"version": "v1",
"created": "Fri, 22 Sep 2006 00:31:54 GMT"
},
{
"version": "v2",
"created": "Mon, 2 Oct 2006 01:03:40 GMT"
},
{
"version": "v3",
"created": "Sat, 25 Nov 2006 01:20:20 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Gong",
"Yiyang",
""
],
[
"Vuckovic",
"Jelena",
""
]
]
|
quant-ph/0609170 | Ryo Namiki | Ryo Namiki, Masato Koashi, Nobuyuki Imoto | Optimal Gaussian $N$-to-$M$ cloning with linear optics and Gaussian
cloning of known-phase coherent states | null | null | null | null | quant-ph | null | We show how to implement the optimal Gaussian $N$-to-$M$ cloning with linear
optics and homodyne detection. We also show that the Gaussian $N$-to-$M$
cloning of known-phase coherent states can be performed with the fidelity
$\sqrt \frac{2 M N}{2M N+M -N}$ by linear optics and homodyne detection, and
with $\frac{2}{\sqrt{1+\frac{1}{N}}+\sqrt {1-\frac{1}{M}}}$ by utilizing
quadrature squeezing. From the classical limit of the cloning (1-to-$\infty$
cloning), a necessary condition of continuous variable quantum key distribution
using known-phase coherent states is provided.
| [
{
"version": "v1",
"created": "Fri, 22 Sep 2006 05:54:05 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Namiki",
"Ryo",
""
],
[
"Koashi",
"Masato",
""
],
[
"Imoto",
"Nobuyuki",
""
]
]
|
quant-ph/0609171 | Karl Tordrup | Karl Tordrup and Klaus M{\o}lmer | Effects of ground state hyperfine shifts in quantum computing with
optically hole burnt materials | 7 pages, 10 figures | null | 10.1103/PhysRevA.75.022316 | null | quant-ph | null | We present an investigation of the effects of constant but random shifts of
the ground hyperfine qubit states in the setting of quantum computing with ion
doped crystals. Complex hyperbolic secant pulses can be used to transfer ions
reliably to electronically excited states, and a perturbative approach is used
to analyse the effect of ground state hyperfine shifts. This analysis shows
that the errors due to the hyperfine shift are dynamically supressed during
gate operation, a fact we attribute to the AC Stark shift. Furthermore we
present an implementation of a controlled phase gate which is resilient to the
effects of the hyperfine shift. Decoherence and decay effects are included in
simulations in order to show that a demonstration of quantum gates is feasible
over the relevant range of system parameters.
| [
{
"version": "v1",
"created": "Fri, 22 Sep 2006 11:03:28 GMT"
}
]
| 2013-05-29T00:00:00 | [
[
"Tordrup",
"Karl",
""
],
[
"Mølmer",
"Klaus",
""
]
]
|
quant-ph/0609172 | Alexandre Matzkin | A. Matzkin and V. Nurock | Are Bohmian trajectories real? On the dynamical mismatch between de
Broglie-Bohm and classical dynamics in semiclassical systems | Figures downgraded to low resolution. V2:Minor changes | Studies in Hist. and Philosophy of Science B, 39, 17, 2008.
[Published version is slightly different and carries the title "Classical and
Bohmian trajectories in semiclassical systems: Mismatch in dynamics, mismatch
in reality?" ] | 10.1016/j.shpsb.2007.04.005 | null | quant-ph hep-th | null | The de Broglie-Bohm interpretation of quantum mechanics aims to give a
realist description of quantum phenomena in terms of the motion of point-like
particles following well-defined trajectories. This work is concerned by the de
Broglie-Bohm account of the properties of semiclassical systems. Semiclassical
systems are quantum systems that display the manifestation of classical
trajectories: the wavefunction and the observable properties of such systems
depend on the trajectories of the classical counterpart of the quantum system.
For example the quantum properties have a regular or disordered aspect
depending on whether the underlying classical system has regular or chaotic
dynamics. In contrast, Bohmian trajectories in semiclassical systems have
little in common with the trajectories of the classical counterpart, creating a
dynamical mismatch relative to the quantum-classical correspondence visible in
these systems. Our aim is to describe this mismatch (explicit illustrations are
given), explain its origin, and examine some of the consequences on the status
of Bohmian trajectories in semiclassical systems. We argue in particular that
semiclassical systems put stronger constraints on the empirical acceptability
and plausibility of Bohmian trajectories because the usual arguments given to
dismiss the mismatch between the classical and the de Broglie-Bohm motions are
weakened by the occurrence of classical trajectories in the quantum
wavefunction of such systems.
| [
{
"version": "v1",
"created": "Fri, 22 Sep 2006 09:59:28 GMT"
},
{
"version": "v2",
"created": "Thu, 12 Apr 2007 17:23:39 GMT"
}
]
| 2008-02-04T00:00:00 | [
[
"Matzkin",
"A.",
""
],
[
"Nurock",
"V.",
""
]
]
|
quant-ph/0609173 | Moiseev Sergei Andreevich | S.A.Moiseev, C.Simon and N.Gisin | Photon Echo Quantum Memory for Arbitrary Non-Stationary Light Fields | 15 pages, 3 figures | null | null | null | quant-ph | null | We develop the theory of an optical quantum memory protocol based on the
three pulse photon echo (PE) in an optically dense medium with controlled
reversible inhomogeneous broadening (CRIB). The wave-function of the retrieved
photon echo field is derived explicitly as a function of an arbitrary input
Data light field. The storage and retrieval of time-bin qubit states based on
the described quantum memory is discussed, and it is shown that the memory
allows to measure the path length difference in an imbalanced interferometer
using short light pulses.
| [
{
"version": "v1",
"created": "Fri, 22 Sep 2006 12:26:29 GMT"
},
{
"version": "v2",
"created": "Wed, 4 Oct 2006 13:15:20 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Moiseev",
"S. A.",
""
],
[
"Simon",
"C.",
""
],
[
"Gisin",
"N.",
""
]
]
|
quant-ph/0609174 | Michael Mehring | Michael Mehring, Klaus Mueller, Ilya Sh. Averbukh, Wolfgang Merkel and
Wolfgang Schleich | NMR experiment factors numbers with Gauss sums | 4 pages 5 figures | null | 10.1103/PhysRevLett.98.120502 | null | quant-ph | null | We factor the number 157573 using an NMR implementation of Gauss sums.
| [
{
"version": "v1",
"created": "Fri, 22 Sep 2006 14:26:47 GMT"
}
]
| 2015-06-26T00:00:00 | [
[
"Mehring",
"Michael",
""
],
[
"Mueller",
"Klaus",
""
],
[
"Averbukh",
"Ilya Sh.",
""
],
[
"Merkel",
"Wolfgang",
""
],
[
"Schleich",
"Wolfgang",
""
]
]
|
quant-ph/0609175 | Berthold-Georg Englert | Syed M. Assad, Jun Suzuki, Berthold-Georg Englert | Raw-data attacks in quantum cryptography with partial tomography | 11 pages, 2 figures | International Journal of Quantum Information 4 (2006) 1003-1012 | null | null | quant-ph | null | We consider a variant of the BB84 protocol for quantum cryptography, the
prototype of tomographically incomplete protocols, where the key is generated
by one-way communication rather than the usual two-way communication. Our
analysis, backed by numerical evidence, establishes thresholds for
eavesdropping attacks on the raw data and on the generated key at quantum bit
error rates of 10% and 6.15%, respectively. Both thresholds are lower than the
threshold for unconditional security in the standard BB84 protocol.
| [
{
"version": "v1",
"created": "Fri, 22 Sep 2006 14:59:57 GMT"
}
]
| 2011-03-15T00:00:00 | [
[
"Assad",
"Syed M.",
""
],
[
"Suzuki",
"Jun",
""
],
[
"Englert",
"Berthold-Georg",
""
]
]
|
quant-ph/0609176 | Massimo Panella | Giuseppe Martinelli and Massimo Panella | An Algorithm to Speed Up Quantum Search | Paper withdraw | null | null | null | quant-ph | null | The paper has been withdrawn because the research work is still in progress.
| [
{
"version": "v1",
"created": "Fri, 22 Sep 2006 16:05:27 GMT"
},
{
"version": "v2",
"created": "Fri, 13 Oct 2006 13:25:05 GMT"
},
{
"version": "v3",
"created": "Mon, 18 Dec 2006 16:58:10 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Martinelli",
"Giuseppe",
""
],
[
"Panella",
"Massimo",
""
]
]
|
quant-ph/0609177 | Manabu Miyamoto | Manabu Miyamoto | Zero energy resonance and the logarithmically slow decay of unstable
multilevel systems | 31 pages, no figures | J. Math. Phys. 47, 082103 (2006) | 10.1063/1.2227260 | null | quant-ph | null | The long time behavior of the reduced time evolution operator for unstable
multilevel systems is studied based on the N-level Friedrichs model in the
presence of a zero energy resonance.The latter means the divergence of the
resolvent at zero energy. Resorting to the technique developed by Jensen and
Kato [Duke Math. J. 46, 583 (1979)], the zero energy resonance of this model is
characterized by the zero energy eigenstate that does not belong to the Hilbert
space. It is then shown that for some kinds of the rational form factors the
logarithmically slow decay of the reduced time evolution operator can be
realized.
| [
{
"version": "v1",
"created": "Fri, 22 Sep 2006 16:26:30 GMT"
},
{
"version": "v2",
"created": "Sat, 23 Sep 2006 02:16:03 GMT"
}
]
| 2015-06-26T00:00:00 | [
[
"Miyamoto",
"Manabu",
""
]
]
|
quant-ph/0609178 | Gerardo Adesso | Gerardo Adesso, Marie Ericsson, Fabrizio Illuminati | Coexistence of unlimited bipartite and genuine multipartite
entanglement: Promiscuous quantum correlations arising from discrete to
continuous variable systems | 8 pages, 4 figures. Extended version. Added discussion about
entanglement sharing and its promiscuous structure in qudits and non-Gaussian
states | Phys. Rev. A 76, 022315 (2007) | 10.1103/PhysRevA.76.022315 | null | quant-ph cond-mat.other math-ph math.MP physics.optics | null | Quantum mechanics imposes 'monogamy' constraints on the sharing of
entanglement. We show that, despite these limitations, entanglement can be
fully 'promiscuous', i.e. simultaneously present in unlimited two-body and
many-body forms in states living in an infinite-dimensional Hilbert space.
Monogamy just bounds the divergence rate of the various entanglement
contributions. This is demonstrated in simple families of N-mode (N >= 4)
Gaussian states of light fields or atomic ensembles, which therefore enable
infinitely more freedom in the distribution of information, as opposed to
systems of individual qubits. Such a finding is of importance for the
quantification, understanding and potential exploitation of shared quantum
correlations in continuous variable systems. We discuss how promiscuity
gradually arises when considering simple families of discrete variable states,
with increasing Hilbert space dimension towards the continuous variable limit.
Such models are somehow analogous to Gaussian states with asymptotically
diverging, but finite squeezing. In this respect, we find that non-Gaussian
states (which in general are more entangled than Gaussian states), exhibit also
the interesting feature that their entanglement is more shareable: in the
non-Gaussian multipartite arena, unlimited promiscuity can be already achieved
among three entangled parties, while this is impossible for Gaussian, even
infinitely squeezed states.
| [
{
"version": "v1",
"created": "Fri, 22 Sep 2006 20:00:22 GMT"
},
{
"version": "v2",
"created": "Wed, 8 Nov 2006 12:13:15 GMT"
},
{
"version": "v3",
"created": "Tue, 29 May 2007 09:47:38 GMT"
}
]
| 2007-08-25T00:00:00 | [
[
"Adesso",
"Gerardo",
""
],
[
"Ericsson",
"Marie",
""
],
[
"Illuminati",
"Fabrizio",
""
]
]
|
quant-ph/0609179 | Sergio Boixo | Sergio Boixo, Steven T. Flammia, Carlton M. Caves, JM Geremia | Generalized Limits for Single-Parameter Quantum Estimation | 4 pages, 1 figure. v2 typos corrected | Phys. Rev. Lett. 98, 090401 (2007) | 10.1103/PhysRevLett.98.090401 | null | quant-ph cond-mat.other | null | We develop generalized bounds for quantum single-parameter estimation
problems for which the coupling to the parameter is described by intrinsic
multi-system interactions. For a Hamiltonian with $k$-system
parameter-sensitive terms, the quantum limit scales as $1/N^k$ where $N$ is the
number of systems. These quantum limits remain valid when the Hamiltonian is
augmented by any parameter independent interaction among the systems and when
adaptive measurements via parameter-independent coupling to ancillas are
allowed.
| [
{
"version": "v1",
"created": "Fri, 22 Sep 2006 20:01:39 GMT"
},
{
"version": "v2",
"created": "Tue, 21 Nov 2006 20:51:15 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Boixo",
"Sergio",
""
],
[
"Flammia",
"Steven T.",
""
],
[
"Caves",
"Carlton M.",
""
],
[
"Geremia",
"JM",
""
]
]
|
quant-ph/0609180 | Masato Koashi | Masato Koashi | Efficient quantum key distribution with practical sources and detectors | 4 pages, 3 figures | null | null | null | quant-ph | null | We consider the security of a system of quantum key distribution (QKD) using
only practical devices. Currently, attenuated laser pulses are widely used and
considered to be the most practical light source. For the receiver of photons,
threshold (or on/off) photon detectors are almost the only choice. Combining
the decoy-state idea and the security argument based on the uncertainty
principle, we show that a QKD system composed of such practical devices can
achieve the unconditional security without any significant penalty in the key
rate and the distance limitation.
| [
{
"version": "v1",
"created": "Sat, 23 Sep 2006 05:46:19 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Koashi",
"Masato",
""
]
]
|
quant-ph/0609181 | David Foulis | D. J. Foulis | Rings with effects | 20 pages | null | null | null | quant-ph | null | A ring with effects (e-ring) is a generalization of the ring of bounded
linear operators on a Hilbert space and the subsystem of effect operators
(positive Hermitian operators dominated by the identity operator). The
POV-measures representing (perhaps fuzzy) quantum mechanical observables take
on their valued in the system of Hilbert-space effect operators. We study and
give several examples of e-rings, including von Neumann algebras and rings of
bounded measurable functions.
| [
{
"version": "v1",
"created": "Sat, 23 Sep 2006 15:34:59 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Foulis",
"D. J.",
""
]
]
|
quant-ph/0609182 | Heng Fan | Gui-Fang Dang, Heng Fan | Optimal Broadcasting of Mixed States | 10 pages, published version | Phys. Rev. A 76, 022323 (2007) | 10.1103/PhysRevA.76.022323 | null | quant-ph | null | The N to M (M>N) universal quantum broadcasting of mixed states are proposed
for qubits system. The broadcasting of mixed states is universal and optimal in
the sense that the shrinking factor is independent of input state and achieves
the upper bound. The quantum broadcasting of mixed qubits is a generalization
of the universal quantum cloning machine for identical pure input states. A new
pure state decompositions of the identical mixed qubits are obtained.
| [
{
"version": "v1",
"created": "Sat, 23 Sep 2006 21:31:03 GMT"
},
{
"version": "v2",
"created": "Thu, 14 Dec 2006 06:48:35 GMT"
},
{
"version": "v3",
"created": "Wed, 9 May 2007 16:22:35 GMT"
},
{
"version": "v4",
"created": "Thu, 22 Nov 2007 03:16:02 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Dang",
"Gui-Fang",
""
],
[
"Fan",
"Heng",
""
]
]
|
quant-ph/0609183 | Andrey Leksin | A. P. Alodjants, S. M. Arakelian, S. N. Bagayev, I. A. Chekhonin, V.
S. Egorov | Quantum cloning in coupled states of optical field and atomic ensemble
by quasi-condensation of polaritons | 11 pages, 1 postscript figure, uses iopart.cls | Journal of Russian Laser Research, Volume 27, Number 5 (2006)
pp.482-491 | null | null | quant-ph | null | We consider a new approach for storing quantum information by macroscopic
atomic excitations of two level atomic system. We offer the original scheme of
quantum cloning of optical field into the cavity polaritons containing the
phase insensitive parametrical amplifier and atomic cell placed in the cavity.
The high temperature quasi-condensation (and/or condensation) phenomenon for
polaritons arising in the cavity under the certain conditions is proposed for
the first time.
| [
{
"version": "v1",
"created": "Mon, 25 Sep 2006 13:37:01 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Alodjants",
"A. P.",
""
],
[
"Arakelian",
"S. M.",
""
],
[
"Bagayev",
"S. N.",
""
],
[
"Chekhonin",
"I. A.",
""
],
[
"Egorov",
"V. S.",
""
]
]
|
quant-ph/0609184 | Antony Valentini | Guido Bacciagaluppi, Antony Valentini | Quantum Theory at the Crossroads: Reconsidering the 1927 Solvay
Conference | 553 pages, 33 figures. Draft of a book (as of Sept. 2006, same as
v1). Published in Oct. 2009, with corrections and an appendix, by Cambridge
University Press (available at
http://www.cambridge.org/catalogue/catalogue.asp?isbn=9780521814218) | G. Bacciagaluppi and A. Valentini, Quantum Theory at the
Crossroads: Reconsidering the 1927 Solvay Conference (Cambridge University
Press, 2009) | null | null | quant-ph gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We reconsider the crucial 1927 Solvay conference in the context of current
research in the foundations of quantum theory. Contrary to folklore, the
interpretation question was not settled at this conference and no consensus was
reached; instead, a range of sharply conflicting views were presented and
extensively discussed. Today, there is no longer an established or dominant
interpretation of quantum theory, so it is important to re-evaluate the
historical sources and keep the interpretation debate open. In this spirit, we
provide a complete English translation of the original proceedings (lectures
and discussions), and give background essays on the three main interpretations
presented: de Broglie's pilot-wave theory, Born and Heisenberg's quantum
mechanics, and Schroedinger's wave mechanics. We provide an extensive analysis
of the lectures and discussions that took place, in the light of current
debates about the meaning of quantum theory. The proceedings contain much
unexpected material, including extensive discussions of de Broglie's pilot-wave
theory (which de Broglie presented for a many-body system), and a "quantum
mechanics" apparently lacking in wave function collapse or fundamental time
evolution. We hope that the book will contribute to the ongoing revival of
research in quantum foundations, as well as stimulate a reconsideration of the
historical development of quantum physics. A more detailed description of the
book may be found in the Preface. (Copyright by Cambridge University Press
(ISBN: 9780521814218).)
| [
{
"version": "v1",
"created": "Sun, 24 Sep 2006 19:29:48 GMT"
},
{
"version": "v2",
"created": "Sat, 24 Oct 2009 16:33:27 GMT"
}
]
| 2009-10-24T00:00:00 | [
[
"Bacciagaluppi",
"Guido",
""
],
[
"Valentini",
"Antony",
""
]
]
|
quant-ph/0609185 | Teiko Heinonen | P. Busch, T. Heinonen, P. Lahti | Heisenberg's Uncertainty Principle | published version | Physics Reports 452 (2007) 155-176 | 10.1016/j.physrep.2007.05.006 | null | quant-ph | null | Heisenberg's uncertainty principle is usually taken to express a limitation
of operational possibilities imposed by quantum mechanics. Here we demonstrate
that the full content of this principle also includes its positive role as a
condition ensuring that mutually exclusive experimental options can be
reconciled if an appropriate trade-off is accepted. The uncertainty principle
is shown to appear in three manifestations, in the form of uncertainty
relations: for the widths of the position and momentum distributions in any
quantum state; for the inaccuracies of any joint measurement of these
quantities; and for the inaccuracy of a measurement of one of the quantities
and the ensuing disturbance in the distribution of the other quantity. Whilst
conceptually distinct, these three kinds of uncertainty relations are shown to
be closely related formally. Finally, we survey models and experimental
implementations of joint measurements of position and momentum and comment
briefly on the status of experimental tests of the uncertainty principle.
| [
{
"version": "v1",
"created": "Mon, 25 Sep 2006 12:27:15 GMT"
},
{
"version": "v2",
"created": "Tue, 5 Dec 2006 02:25:57 GMT"
},
{
"version": "v3",
"created": "Tue, 30 Oct 2007 21:46:53 GMT"
}
]
| 2007-10-31T00:00:00 | [
[
"Busch",
"P.",
""
],
[
"Heinonen",
"T.",
""
],
[
"Lahti",
"P.",
""
]
]
|
quant-ph/0609186 | Jian-Ming Cai | Jian-Ming Cai, Zheng-Wei Zhou, Guang-Can Guo | Fully multi-qubit entangled states | 9 pages, 1 figure. Extra conditions for theorem 2 and corollary 1 are
added | null | null | null | quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the properties of different levels of entanglement in graph
states which correspond to connected graphs. Combining the operational
definition of graph states and the postulates of entanglement measures, we
prove that in connected graph states of N>3 qubits there is no genuine
three-qubit entanglement. For certain classes of graph states, all genuine
k-qubit entanglement, 2\leq k\leq N-1, among every k qubits vanishes. These
results about connected graph states naturally lead to the definition of fully
multi-qubit entangled states. We also find that the connected graph states of
four qubits is one but not the only one class of fully four-qubit entangled
states.
| [
{
"version": "v1",
"created": "Mon, 25 Sep 2006 02:09:00 GMT"
},
{
"version": "v2",
"created": "Mon, 11 Dec 2006 09:04:31 GMT"
},
{
"version": "v3",
"created": "Sun, 25 Mar 2007 03:07:21 GMT"
},
{
"version": "v4",
"created": "Fri, 11 Jul 2008 07:19:56 GMT"
}
]
| 2008-07-11T00:00:00 | [
[
"Cai",
"Jian-Ming",
""
],
[
"Zhou",
"Zheng-Wei",
""
],
[
"Guo",
"Guang-Can",
""
]
]
|
quant-ph/0609187 | Xiangyao Wu | Xiang-Yao Wu, Bai-Jun Zhang, Xiao-Jing Liu, Li Wang, Bing Liu, Xi-Hui
Fan, Yi-Qing Guo | Quantum theory of electronic double-slit diffraction | 9pages, 14figures | null | 10.1088/0256-307X/24/10/008 | null | quant-ph | null | The phenomena of electron, neutron, atomic and molecular diffraction have
been studied by many experiments, and these experiments are explained by some
theoretical works. In this paper, we study electronic double-slit diffraction
with quantum mechanical approach. We can obtain the results: (1) When the slit
width $a$ is in the range of $3\lambda\sim 50\lambda$ we can obtain the obvious
diffraction patterns. (2) when the ratio of $\frac{d+a}{a}=n (n=1, 2,
3,\cdot\cdot\cdot)$, order $2n, 3n, 4n,\cdot\cdot\cdot$ are missing in
diffraction pattern. (3)When the ratio of $\frac{d+a}{a}\neq n (n=1, 2,
3,\cdot\cdot\cdot)$, there isn't missing order in diffraction pattern. (4) We
also find a new quantum mechanics effect that the slit thickness $c$ has a
large affect to the electronic diffraction patterns. We think all the
predictions in our work can be tested by the electronic double-slit diffraction
experiment.
| [
{
"version": "v1",
"created": "Mon, 25 Sep 2006 03:40:40 GMT"
},
{
"version": "v2",
"created": "Sat, 3 Mar 2007 03:15:10 GMT"
},
{
"version": "v3",
"created": "Tue, 24 Apr 2007 11:02:47 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Wu",
"Xiang-Yao",
""
],
[
"Zhang",
"Bai-Jun",
""
],
[
"Liu",
"Xiao-Jing",
""
],
[
"Wang",
"Li",
""
],
[
"Liu",
"Bing",
""
],
[
"Fan",
"Xi-Hui",
""
],
[
"Guo",
"Yi-Qing",
""
]
]
|
quant-ph/0609188 | Vincent Delaubert | Vincent Delaubert (ACQAO, LKB - Jussieu), Nicolas Treps (LKB -
Jussieu), Claude Fabre (LKB - Jussieu), Hans A. Bachor (ACQAO), Philippe
R\'efr\'egier (IF) | Quantum limits in image processing | 4 pages, two figures | null | null | null | quant-ph | null | We determine the bound to the maximum achievable sensitivity in the
estimation of a scalar parameter from the information contained in an optical
image in the presence of quantum noise. This limit, based on the Cramer-Rao
bound, is valid for any image processing protocol. It is calculated both in the
case of a shot noise limited image and of a non-classical illumination. We also
give practical experimental implementations allowing us to reach this absolute
limit.
| [
{
"version": "v1",
"created": "Mon, 25 Sep 2006 08:57:20 GMT"
}
]
| 2016-08-16T00:00:00 | [
[
"Delaubert",
"Vincent",
"",
"ACQAO, LKB - Jussieu"
],
[
"Treps",
"Nicolas",
"",
"LKB -\n Jussieu"
],
[
"Fabre",
"Claude",
"",
"LKB - Jussieu"
],
[
"Bachor",
"Hans A.",
"",
"ACQAO"
],
[
"Réfrégier",
"Philippe",
"",
"IF"
]
]
|
quant-ph/0609189 | Andrey Leksin | A. P. Alodjants, S. M. Arakelian | Quantum storage and cloning of light states in EIT-like medium | 13 pages, 4 postscript figures, uses ws-ijmpb.cls | Int. J. of Modern Physics B, 20 (2006) 1593-1605 | 10.1142/S0217979206034145 | null | quant-ph | null | In the paper we consider a new approach for storage and cloning of quantum
information by three level atomic (molecular) systems in the presence of the
electromagnetically induced transparency (EIT) effect. For that, the various
schemes of transformation into the bright and dark polaritons for quantum
states of optical field in the medium are proposed. Physical conditions of
realization of quantum nondemolition (QND) storage of quantum optical state are
formulated for the first time. We have shown that the best storage and cloning
of can be achieved with the atomic ensemble in the Bose-Einstein condensation
state. We discuss stimulated Raman two-color photoassociation for experimental
realization of the schemes under consideration.
| [
{
"version": "v1",
"created": "Mon, 25 Sep 2006 13:01:23 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Alodjants",
"A. P.",
""
],
[
"Arakelian",
"S. M.",
""
]
]
|
quant-ph/0609190 | James B. Hartle | Murray Gell-Mann (Santa Fe Institute) and James Hartle (University of
California Santa Barbara) | Quasiclassical Coarse Graining and Thermodynamic Entropy | 17 pages, 0 figures, revtex4, Dedicated to Rafael Sorkin on his 60th
birthday, minor corrections | Phys.Rev.A76:022104,2007 | 10.1103/PhysRevA.76.022104 | null | quant-ph cond-mat.stat-mech gr-qc hep-th | null | Our everyday descriptions of the universe are highly coarse-grained,
following only a tiny fraction of the variables necessary for a perfectly
fine-grained description. Coarse graining in classical physics is made natural
by our limited powers of observation and computation. But in the modern quantum
mechanics of closed systems, some measure of coarse graining is inescapable
because there are no non-trivial, probabilistic, fine-grained descriptions.
This essay explores the consequences of that fact. Quantum theory allows for
various coarse-grained descriptions some of which are mutually incompatible.
For most purposes, however, we are interested in the small subset of
``quasiclassical descriptions'' defined by ranges of values of averages over
small volumes of densities of conserved quantities such as energy and momentum
and approximately conserved quantities such as baryon number. The
near-conservation of these quasiclassical quantities results in approximate
decoherence, predictability, and local equilibrium, leading to closed sets of
equations of motion. In any description, information is sacrificed through the
coarse graining that yields decoherence and gives rise to probabilities for
histories. In quasiclassical descriptions, further information is sacrificed in
exhibiting the emergent regularities summarized by classical equations of
motion. An appropriate entropy measures the loss of information. For a
``quasiclassical realm'' this is connected with the usual thermodynamic entropy
as obtained from statistical mechanics. It was low for the initial state of our
universe and has been increasing since.
| [
{
"version": "v1",
"created": "Mon, 25 Sep 2006 18:50:50 GMT"
},
{
"version": "v2",
"created": "Tue, 19 Dec 2006 19:11:59 GMT"
},
{
"version": "v3",
"created": "Wed, 16 May 2007 18:03:16 GMT"
}
]
| 2008-11-26T00:00:00 | [
[
"Gell-Mann",
"Murray",
"",
"Santa Fe Institute"
],
[
"Hartle",
"James",
"",
"University of\n California Santa Barbara"
]
]
|
quant-ph/0609191 | Daniel Felinto | D. Felinto, C. W. Chou, J. Laurat, E. W. Schomburg, H. de Riedmatten,
and H. J. Kimble | Conditional control of the quantum states of remote atomic memories for
quantum networking | 10 pages, 8 figures; Minor corrections. References updated. Published
at Nature Physics 2, Advanced Online Publication of 10/29 (2006) | null | 10.1038/nphys450 | null | quant-ph | null | Quantum networks hold the promise for revolutionary advances in information
processing with quantum resources distributed over remote locations via
quantum-repeater architectures. Quantum networks are composed of nodes for
storing and processing quantum states, and of channels for transmitting states
between them. The scalability of such networks relies critically on the ability
to perform conditional operations on states stored in separated quantum
memories. Here we report the first implementation of such conditional control
of two atomic memories, located in distinct apparatuses, which results in a
28-fold increase of the probability of simultaneously obtaining a pair of
single photons, relative to the case without conditional control. As a first
application, we demonstrate a high degree of indistinguishability for remotely
generated single photons by the observation of destructive interference of
their wavepackets. Our results demonstrate experimentally a basic principle for
enabling scalable quantum networks, with applications as well to linear optics
quantum computation.
| [
{
"version": "v1",
"created": "Mon, 25 Sep 2006 18:57:40 GMT"
},
{
"version": "v2",
"created": "Thu, 16 Nov 2006 22:46:23 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Felinto",
"D.",
""
],
[
"Chou",
"C. W.",
""
],
[
"Laurat",
"J.",
""
],
[
"Schomburg",
"E. W.",
""
],
[
"de Riedmatten",
"H.",
""
],
[
"Kimble",
"H. J.",
""
]
]
|
quant-ph/0609192 | Mladen Pavicic | Norman D. Megill and Mladen Pavicic | Mayet-Godowski Hilbert Lattice Equations | 10 pages | null | null | null | quant-ph | null | Several new results in the field of Hilbert lattice equations based on states
defined on the lattice as well as novel techniques used to arrive at these
results are presented. An open problem of Mayet concerning Hilbert lattice
equations based on Hilbert-space-valued states is answered.
| [
{
"version": "v1",
"created": "Tue, 26 Sep 2006 01:29:48 GMT"
},
{
"version": "v2",
"created": "Tue, 26 Sep 2006 21:03:17 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Megill",
"Norman D.",
""
],
[
"Pavicic",
"Mladen",
""
]
]
|
quant-ph/0609193 | David Press | David Press, Stephan Goetzinger, Stephan Reitzenstein, Carolin
Hofmann, Andreas Loeffler, Martin Kamp, Alfred Forchel, and Yoshihisa
Yamamoto | Photon Antibunching from a Single Quantum Dot-Microcavity System in the
Strong Coupling Regime | 4 pages, 4 eps figures. New data added: measurement of
anti-correlation between exciton and cavity emission modes | null | 10.1103/PhysRevLett.98.117402 | null | quant-ph | null | We observe antibunching in the photons emitted from a strongly-coupled single
quantum dot and pillar microcavity in resonance. When the quantum dot was
spectrally detuned from the cavity mode, the cavity emission remained
antibunched, and also anticorrelated from the quantum dot emission. Resonant
pumping of the selected quantum dot via an excited state enabled these
observations by eliminating the background emitters that are usually coupled to
the cavity. This device demonstrates an on-demand single photon source
operating in the strong coupling regime, with a Purcell factor of 61 and
quantum effciency of 97%
| [
{
"version": "v1",
"created": "Tue, 26 Sep 2006 04:06:43 GMT"
},
{
"version": "v2",
"created": "Mon, 2 Oct 2006 06:29:24 GMT"
},
{
"version": "v3",
"created": "Tue, 20 Feb 2007 05:45:09 GMT"
}
]
| 2015-06-26T00:00:00 | [
[
"Press",
"David",
""
],
[
"Goetzinger",
"Stephan",
""
],
[
"Reitzenstein",
"Stephan",
""
],
[
"Hofmann",
"Carolin",
""
],
[
"Loeffler",
"Andreas",
""
],
[
"Kamp",
"Martin",
""
],
[
"Forchel",
"Alfred",
""
],
[
"Yamamoto",
"Yoshihisa",
""
]
]
|
quant-ph/0609194 | Galina L. Klimchitskaya | F. Chen, G.L. Klimchitskaya, V.M. Mostepanenko, and U. Mohideen | Demonstration of the difference Casimir force for samples with different
charge carrier densities | 4 pages, 4 figures, to appear in Phys. Rev. Lett | Phys. Rev. Lett., v.97, N 17, p.170402-1-4 (2006). | 10.1103/PhysRevLett.97.170402 | null | quant-ph cond-mat.mtrl-sci | null | A measurement of the Casimir force between a gold coated sphere and two Si
plates of different carrier densities is performed using a high vacuum based
atomic force microscope. The results are compared with the Lifshitz theory and
good agreement is found. Our experiment demonstrates that by changing the
carrier density of the semiconductor plate by several orders of magnitude it is
possible to modify the Casimir interaction. This result may find applications
in nanotechnology.
| [
{
"version": "v1",
"created": "Tue, 26 Sep 2006 08:04:57 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Chen",
"F.",
""
],
[
"Klimchitskaya",
"G. L.",
""
],
[
"Mostepanenko",
"V. M.",
""
],
[
"Mohideen",
"U.",
""
]
]
|
quant-ph/0609195 | Wolfgang Mauerer | Wolfgang Mauerer, Christine Silberhorn | Passive decoy state quantum key distribution: Closing the gap to perfect
sources | 4 pages, 3 figures. State preparation corrected | Phys. Rev. A 75, 050305(R) (2007) | 10.1103/PhysRevA.75.050305 | null | quant-ph | null | We propose a quantum key distribution scheme which closely matches the
performance of a perfect single photon source. It nearly attains the physical
upper bound in terms of key generation rate and maximally achievable distance.
Our scheme relies on a practical setup based on a parametric downconversion
source and present-day, non-ideal photon-number detection. Arbitrary
experimental imperfections which lead to bit errors are included. We select
decoy states by classical post-processing. This allows to improve the effective
signal statistics and achievable distance.
| [
{
"version": "v1",
"created": "Tue, 26 Sep 2006 13:10:36 GMT"
},
{
"version": "v2",
"created": "Tue, 17 Oct 2006 17:42:12 GMT"
}
]
| 2007-10-15T00:00:00 | [
[
"Mauerer",
"Wolfgang",
""
],
[
"Silberhorn",
"Christine",
""
]
]
|
quant-ph/0609196 | Kedar Ranade | Kedar S. Ranade, Gernot Alber | Asymptotic correctability of Bell-diagonal qudit states and lower bounds
on tolerable error probabilities in quantum cryptography | submitted to J. Phys. A | J. Phys. A: Math. Theor. 40 (2007), 139 - 153 | 10.1088/1751-8113/40/1/008 | doi:10.1088/1751-8113/40/1/008 | quant-ph | null | The concept of asymptotic correctability of Bell-diagonal quantum states is
generalised to elementary quantum systems of higher dimensions. Based on these
results basic properties of quantum state purification protocols are
investigated which are capable of purifying tensor products of Bell-diagonal
states and which are based on $B$-steps of the Gottesman-Lo-type with the
subsequent application of a Calderbank-Shor-Steane quantum code. Consequences
for maximum tolerable error rates of quantum cryptographic protocols are
discussed.
| [
{
"version": "v1",
"created": "Tue, 26 Sep 2006 11:36:01 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Ranade",
"Kedar S.",
""
],
[
"Alber",
"Gernot",
""
]
]
|
quant-ph/0609197 | David Vitali | D. Vitali, S. Gigan, A. Ferreira, H. R. Boehm, P. Tombesi, A.
Guerreiro, V. Vedral, A. Zeilinger, and M. Aspelmeyer | Optomechanical entanglement between a movable mirror and a cavity field | 4 pages, 3 figures | Phys. Rev. Lett. 98, 030405 (2007) | 10.1103/PhysRevLett.98.030405 | null | quant-ph | null | We show how stationary entanglement between an optical cavity field mode and
a macroscopic vibrating mirror can be generated by means of radiation pressure.
We also show how the generated optomechanical entanglement can be quantified
and we suggest an experimental readout-scheme to fully characterize the
entangled state. Surprisingly, such optomechanical entanglement is shown to
persist for environment temperatures above 20K using state-of-the-art
experimental parameters.
| [
{
"version": "v1",
"created": "Tue, 26 Sep 2006 13:17:21 GMT"
},
{
"version": "v2",
"created": "Thu, 7 Dec 2006 14:37:15 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Vitali",
"D.",
""
],
[
"Gigan",
"S.",
""
],
[
"Ferreira",
"A.",
""
],
[
"Boehm",
"H. R.",
""
],
[
"Tombesi",
"P.",
""
],
[
"Guerreiro",
"A.",
""
],
[
"Vedral",
"V.",
""
],
[
"Zeilinger",
"A.",
""
],
[
"Aspelmeyer",
"M.",
""
]
]
|
quant-ph/0609198 | Chris Dewdney | George Horton and Chris Dewdney | Energy momentum flows for the massive vector field | 20 pages, 6 figures | null | null | null | quant-ph | null | We present a causal trajectory interpretation for the massive vector field,
based on the flows of rest energy and a conserved density defined using the
time-like eigenvectors and eigenvalues of the stress-energy-momentum tensor.
This work extends our previous work which used a similar procedure for the
scalar field. The massive, spin-one, complex vector field is discussed in
detail and solutions are classified using the Pauli-Lubanski spin vector. The
flows of energy-momentum are illustrated in a simple example of standing waves
in a plane.
| [
{
"version": "v1",
"created": "Tue, 26 Sep 2006 13:35:56 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Horton",
"George",
""
],
[
"Dewdney",
"Chris",
""
]
]
|
quant-ph/0609199 | Lucas Celeri Ms. | L. C. C\'eleri, M. A. de Ponte, C. J. Villas-Boas and M. H. Y. Moussa | Switching off the reservoir through nonstationary quantum systems | 11 pages, 1 figure | null | null | null | quant-ph | null | In this paper we demonstrate that the inevitable action of the environment
can be substantially weakened when considering appropriate nonstationary
quantum systems. Beyond protecting quantum states against decoherence, an
oscillating frequency can be engineered to make the system-reservoir coupling
almost negligible. Therefore, differently from previously-reported protecting
schemes, our technique does not require a previous knowledge of the state to be
protected. We show, in the domain of cavity quantum electrodynamics, how to
engineer such a nonstationary cavity mode through its dispersive interaction
with a driven two-level atom.
| [
{
"version": "v1",
"created": "Tue, 26 Sep 2006 13:47:02 GMT"
},
{
"version": "v2",
"created": "Mon, 26 Feb 2007 18:05:33 GMT"
},
{
"version": "v3",
"created": "Tue, 27 Feb 2007 17:06:41 GMT"
},
{
"version": "v4",
"created": "Mon, 9 Apr 2007 18:58:20 GMT"
}
]
| 2016-08-16T00:00:00 | [
[
"Céleri",
"L. C.",
""
],
[
"de Ponte",
"M. A.",
""
],
[
"Villas-Boas",
"C. J.",
""
],
[
"Moussa",
"M. H. Y.",
""
]
]
|
quant-ph/0609200 | Celso J. Villas Boas Dr. | R. L. Rodrigues, M. H. Y. Moussa, and C. J. Villas-Boas | Engineering phonon-photon interactions with a driven trapped ion in a
cavity | 15 pages, 3 figures. To appear in Physical Review A | null | 10.1103/PhysRevA.74.063811 | null | quant-ph | null | We show how to generate quadratic and bi-quadratic phonon-photon interactions
through a driven three-level ion inside a cavity. With such a system it is
possible to squeeze the cavity-field state, the ion motional state or even the
entangled phonon-photon state. We present a detailed analysis of the
cavity-field squeezing process, distinguishing three different regimes of this
amplification mechanism: the subcritical, critical, and supercritical regimes,
which depend, apart from the coupling parameters, on the excitation of the
vibrational state. As an application of the engineered Hamiltonians, we show
how to implement a Fock-state filter for the vibrational mode. New aspects of
the technique of adiabatic elimination emerge in this analysis.
| [
{
"version": "v1",
"created": "Tue, 26 Sep 2006 14:04:30 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Rodrigues",
"R. L.",
""
],
[
"Moussa",
"M. H. Y.",
""
],
[
"Villas-Boas",
"C. J.",
""
]
]
|
quant-ph/0609201 | Matthias Staudt U. | M. U. Staudt, S. R. Hastings-Simon, M. Nilsson, M. Afzelius, V.
Scarani, R. Ricken, H. Suche, W. Sohler, W. Tittel, N. Gisin | Fidelity of an optical memory based on stimulated photon echoes | null | null | 10.1103/PhysRevLett.98.113601 | null | quant-ph | null | We investigated the preservation of information encoded into the relative
phase and amplitudes of optical pulses during storage and retrieval in an
optical memory based on stimulated photon echo. By interfering photon echoes
produced in a Ti-indiffused single-mode Er-doped LiNbO$_{3}$ waveguiding
structure at telecom wavelength, we found that decoherence in the atomic medium
translates only as losses (and not as degradation) of information, as long as
the data pulse series is short compared to the atomic decoherence time. The
experimentally measured value of the visibility for interfering echoes is close
to 100 %. In addition to the expected three-pulse photon-echo interferences we
also observed interference due to a four-pulse photon echo. Our findings are of
particular interest for future long-distance quantum communication protocols,
which rely on the reversible transfer of quantum states between light and atoms
with high fidelity.
| [
{
"version": "v1",
"created": "Tue, 26 Sep 2006 15:13:33 GMT"
}
]
| 2015-06-26T00:00:00 | [
[
"Staudt",
"M. U.",
""
],
[
"Hastings-Simon",
"S. R.",
""
],
[
"Nilsson",
"M.",
""
],
[
"Afzelius",
"M.",
""
],
[
"Scarani",
"V.",
""
],
[
"Ricken",
"R.",
""
],
[
"Suche",
"H.",
""
],
[
"Sohler",
"W.",
""
],
[
"Tittel",
"W.",
""
],
[
"Gisin",
"N.",
""
]
]
|
quant-ph/0609202 | Fernando M. Cucchietti | Fernando M. Cucchietti | Loschmidt echo in the Bose-Hubbard model: turning back time in an
optical lattice | null | J. Opt. Soc. Am. B 27, A30-A35 (2010) | 10.1364/JOSAB.27.000A30 | LA-UR-06-5903 | quant-ph cond-mat.other physics.atom-ph | null | I show how to perform a Loschmidt echo (time reversal) in the Bose-Hubbard
model implemented with cold bosonic atoms in an optical lattice. The echo is
obtained by applying a linear phase imprint on the lattice and a change in
magnetic field to tune the boson-boson scattering length through a Feshbach
resonance. I discuss how the echo can measure the fidelity of the quantum
simulation, the intensity of an external potential (e.g. gravity), or the
critical point of the superfluid-insulator quantum phase transition.
| [
{
"version": "v1",
"created": "Tue, 26 Sep 2006 19:49:29 GMT"
}
]
| 2010-03-12T00:00:00 | [
[
"Cucchietti",
"Fernando M.",
""
]
]
|
quant-ph/0609203 | Goetz S. Uhrig | G\"otz S. Uhrig | Keeping a Quantum Bit Alive by Optimized $\pi$-Pulse Sequences | 4 pages, 2 figures; revised version with additional references for
better context, more stringent discussion | PRL 98, 100504 (2007) | 10.1103/PhysRevLett.98.100504 | null | quant-ph cond-mat.mes-hall cond-mat.stat-mech cond-mat.str-el | null | A general strategy to maintain the coherence of a quantum bit is proposed.
The analytical result is derived rigorously including all memory and
back-action effects. It is based on an optimized $\pi$-pulse sequence for
dynamic decoupling extending the Carr-Purcell-Meiboom-Gill (CPMG) cycle. The
optimized sequence is very efficient, in particular for strong couplings to the
environment.
| [
{
"version": "v1",
"created": "Tue, 26 Sep 2006 19:58:16 GMT"
},
{
"version": "v2",
"created": "Thu, 8 Feb 2007 09:15:00 GMT"
}
]
| 2011-11-09T00:00:00 | [
[
"Uhrig",
"Götz S.",
""
]
]
|
quant-ph/0609204 | Peter Richter | Peter C. Richter | Quantum speedup of classical mixing processes | 13 pages; v2 revised several parts | Phys. Rev. A 76, 042306 (2007) | 10.1103/PhysRevA.76.042306 | null | quant-ph | null | Most approximation algorithms for #P-complete problems (e.g., evaluating the
permanent of a matrix or the volume of a polytope) work by reduction to the
problem of approximate sampling from a distribution $\pi$ over a large set
$\S$. This problem is solved using the {\em Markov chain Monte Carlo} method: a
sparse, reversible Markov chain $P$ on $\S$ with stationary distribution $\pi$
is run to near equilibrium. The running time of this random walk algorithm, the
so-called {\em mixing time} of $P$, is $O(\delta^{-1} \log 1/\pi_*)$ as shown
by Aldous, where $\delta$ is the spectral gap of $P$ and $\pi_*$ is the minimum
value of $\pi$. A natural question is whether a speedup of this classical
method to $O(\sqrt{\delta^{-1}} \log 1/\pi_*)$, the diameter of the graph
underlying $P$, is possible using {\em quantum walks}.
We provide evidence for this possibility using quantum walks that {\em
decohere} under repeated randomized measurements. We show: (a) decoherent
quantum walks always mix, just like their classical counterparts, (b) the
mixing time is a robust quantity, essentially invariant under any smooth form
of decoherence, and (c) the mixing time of the decoherent quantum walk on a
periodic lattice $\Z_n^d$ is $O(n d \log d)$, which is indeed
$O(\sqrt{\delta^{-1}} \log 1/\pi_*)$ and is asymptotically no worse than the
diameter of $\Z_n^d$ (the obvious lower bound) up to at most a logarithmic
factor.
| [
{
"version": "v1",
"created": "Tue, 26 Sep 2006 20:52:12 GMT"
},
{
"version": "v2",
"created": "Thu, 5 Apr 2007 14:53:53 GMT"
}
]
| 2011-11-09T00:00:00 | [
[
"Richter",
"Peter C.",
""
]
]
|
quant-ph/0609205 | Vladimir Korepin | Vladimir E. Korepin and Brenno C. Vallilo | Group Theoretical Formulation of Quantum Partial Search Algorithm | 12 pages | Prog. Theor. Phys. Vol. 116, No. 5 (2006), p. 783 | 10.1143/PTP.116.783 | YIPT-SB-06-41 | quant-ph cs.DS math.GR | null | Searching and sorting used as a subroutine in many important algorithms.
Quantum algorithm can find a target item in a database faster than any
classical algorithm. One can trade accuracy for speed and find a part of the
database (a block) containing the target item even faster, this is partial
search. An example is the following: exact address of the target item is given
by a sequence of many bits, but we need to know only some of them. More
generally partial search considers the following problem: a database is
separated into several blocks. We want to find a block with the target item,
not the target item itself. In this paper we reformulate quantum partial search
algorithm in terms of group theory.
| [
{
"version": "v1",
"created": "Wed, 27 Sep 2006 00:32:33 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Korepin",
"Vladimir E.",
""
],
[
"Vallilo",
"Brenno C.",
""
]
]
|
quant-ph/0609206 | Joerg Evers | Mohammad Mahmoudi and Joerg Evers | Light propagation through closed-loop atomic media beyond the
multiphoton resonance condition | 10 pages, 8 figures | Phys. Rev. A. 74, 063827 (2006) | 10.1103/PhysRevA.74.063827 | null | quant-ph | null | The light propagation of a probe field pulse in a four-level double-lambda
type system driven by laser fields that form a closed interaction loop is
studied. Due to the finite frequency width of the probe pulse, a
time-independent analysis relying on the multiphoton resonance assumption is
insufficient. Thus we apply a Floquet decomposition of the equations of motion
to solve the time-dependent problem beyond the multiphoton resonance condition.
We find that the various Floquet components can be interpreted in terms of
different scattering processes, and that the medium response oscillating in
phase with the probe field in general is not phase-dependent. The phase
dependence arises from a scattering of the coupling fields into the probe field
mode at a frequency which in general differs from the probe field frequency. We
thus conclude that in particular for short pulses with a large frequency width,
inducing a closed loop interaction contour may not be advantageous, since
otherwise the phase-dependent medium response may lead to a distortion of the
pulse shape. Finally, using our time-dependent analysis, we demonstrate that
both the closed-loop and the non-closed loop configuration allow for sub- and
superluminal light propagation with small absorption or even gain. Further, we
identify one of the coupling field Rabi frequencies as a control parameter that
allows to conveniently switch between sub- and superluminal light propagation.
| [
{
"version": "v1",
"created": "Wed, 27 Sep 2006 07:33:17 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Mahmoudi",
"Mohammad",
""
],
[
"Evers",
"Joerg",
""
]
]
|
quant-ph/0609207 | Gui Lu Long | Kai Wen and Gui Lu Long | One-party Quantum Error Correcting Codes for Unbalanced Errors:
Principles and Application to Quantum Dense Coding and Quantum Secure Direct
Communications | 15 pages and 2 figures and 3 tables | null | null | null | quant-ph | null | In this article, we present the unbalanced quantum error correcting
codes(one-party-QECC), a novel idea for correcting unbalanced quantum errors.
In some quantum communication tasks using entangled pairs, the error
distributions between two parts of the pairs are unbalanced, and. one party
holds the whole entangled pairs at the final stage, and he or she is able to
perform joint measurements on the pairs. In this situation the proposed
one-party-QECC can improve error correction by allowing a higher tolerated
error rate. We have established the general correspondence between linear
classical codes and the one-party-QECC, and we have given the general
definition for this type quantum error correcting codes.It has been shown that
the one-party-QECC can correct errors as long as the error threshold is not
larger than 0.5. The one-party-QECC works even for fidelity less than 0.5 as
long as it is larger than 0.25. We give several concrete examples of the
one-party-QECC. We provide the applications of one-party-QECC in quantum dense
coding so that it can function in noisy channels. As a result, a large number
of quantum secure direct communication protocols based on dense coding is also
able to be protected by this new type of one-party-QECC.
| [
{
"version": "v1",
"created": "Wed, 27 Sep 2006 09:29:34 GMT"
},
{
"version": "v2",
"created": "Wed, 28 Feb 2007 02:08:01 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Wen",
"Kai",
""
],
[
"Long",
"Gui Lu",
""
]
]
|
quant-ph/0609208 | Helene Perrin | Emiliya Dimova (LAC), Olivier Morizot (LPL), Guillaume Stern (LAC),
Carlos L. Garrido Alzar (LPL), Andrea Fioretti (LAC), Vincent Lorent (LPL),
Daniel Comparat (LAC), H\'el\`ene Perrin (LPL), Pierre Pillet (LAC) | Continuous transfer and laser guiding between two cold atom traps | 10 pages, 8 figures | European physical Journal D 42 (2007) 299-308 | 10.1140/epjd/e2007-00022-0 | null | quant-ph | null | We have demonstrated and modeled a simple and efficient method to transfer
atoms from a first Magneto-Optical Trap (MOT) to a second one. Two independent
setups, with cesium and rubidium atoms respectively, have shown that a high
power and slightly diverging laser beam optimizes the transfer between the two
traps when its frequency is red-detuned from the atomic transition. This
pushing laser extracts a continuous beam of slow and cold atoms out of the
first MOT and also provides a guiding to the second one through the dipolar
force. In order to optimize the transfer efficiency, the dependence of the
atomic flux on the pushing laser parameters (power, detuning, divergence and
waist) is investigated. The atomic flux is found to be proportional to the
first MOT loading rate. Experimentally, the transfer efficiency reaches 70%,
corresponding to a transfer rate up to 2.7x10^8 atoms/s with a final velocity
of 5.5 m/s. We present a simple analysis of the atomic motion inside the
pushing-guiding laser, in good agreement with the experimental data.
| [
{
"version": "v1",
"created": "Wed, 27 Sep 2006 09:57:49 GMT"
},
{
"version": "v2",
"created": "Fri, 6 Apr 2007 08:44:12 GMT"
}
]
| 2016-08-16T00:00:00 | [
[
"Dimova",
"Emiliya",
"",
"LAC"
],
[
"Morizot",
"Olivier",
"",
"LPL"
],
[
"Stern",
"Guillaume",
"",
"LAC"
],
[
"Alzar",
"Carlos L. Garrido",
"",
"LPL"
],
[
"Fioretti",
"Andrea",
"",
"LAC"
],
[
"Lorent",
"Vincent",
"",
"LPL"
],
[
"Comparat",
"Daniel",
"",
"LAC"
],
[
"Perrin",
"Hélène",
"",
"LPL"
],
[
"Pillet",
"Pierre",
"",
"LAC"
]
]
|
quant-ph/0609209 | Svozil Karl | Karl Svozil | Contexts in quantum, classical and partition logic | Invited contribution to Handbook of Quantum Logic, edited by Kurt
Engesser et al | Handbook of Quantum Logic and Quantum Structures, ed. by Kurt
Engesser, Dov M. Gabbay and Daniel Lehmann (Elsevier, Amsterdam, 2008), pp.
551-586 | null | null | quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Contexts are maximal collections of co-measurable observables "bundled
together" to form a "quasi-classical mini-universe." Different notions of
contexts are discussed for classical, quantum and generalized urn-automaton
systems.
| [
{
"version": "v1",
"created": "Wed, 27 Sep 2006 10:44:03 GMT"
},
{
"version": "v2",
"created": "Wed, 14 May 2008 14:25:15 GMT"
},
{
"version": "v3",
"created": "Thu, 20 Nov 2008 15:58:46 GMT"
},
{
"version": "v4",
"created": "Thu, 4 Dec 2008 11:26:11 GMT"
}
]
| 2009-10-13T00:00:00 | [
[
"Svozil",
"Karl",
""
]
]
|
quant-ph/0609210 | Mauro Paternostro | M. Paternostro, D. Vitali, S. Gigan, M. S. Kim, C. Brukner, J. Eisert,
M. Aspelmeyer | Creating and probing macroscoping entanglement with light | 4 pages, 5 figure, RevTeX4 | Phys. Rev. Lett. 99, 250401 (2007). | 10.1103/PhysRevLett.99.250401 | null | quant-ph | null | We describe a scheme showing signatures of macroscopic optomechanical
entanglement generated by radiation pressure in a cavity system with a massive
movable mirror. The system we consider reveals genuine multipartite
entanglement. We highlight the way the entanglement involving the inaccessible
massive object is unravelled, in our scheme, by means of field-field quantum
correlations.
| [
{
"version": "v1",
"created": "Wed, 27 Sep 2006 10:53:24 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Paternostro",
"M.",
""
],
[
"Vitali",
"D.",
""
],
[
"Gigan",
"S.",
""
],
[
"Kim",
"M. S.",
""
],
[
"Brukner",
"C.",
""
],
[
"Eisert",
"J.",
""
],
[
"Aspelmeyer",
"M.",
""
]
]
|
quant-ph/0609211 | Wang Zhi Yong | Zhi-Yong Wang, Cai-Dong Xiong | How to Introduce Time Operator | 17 pages, accepted to be published in Annals of Physics | Annals of Physics (New York) 322, 2304-2314 (2007) | 10.1016/j.aop.2006.10.007 | null | quant-ph | null | Time operator can be introduced by three different approaches: by pertaining
it to dynamical variables; by quantizing the classical expression of time;
taken as the restriction of energy shift generator to the Hilbert space of a
physical system.
| [
{
"version": "v1",
"created": "Wed, 27 Sep 2006 13:01:22 GMT"
},
{
"version": "v2",
"created": "Tue, 9 Jan 2007 12:12:36 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Wang",
"Zhi-Yong",
""
],
[
"Xiong",
"Cai-Dong",
""
]
]
|
quant-ph/0609212 | Jonathan Silman | J. Silman and B. Reznik | Long-range entanglement in the Dirac vacuum | 11 pages, 1 figure | Phys. Rev. A 75, 052307 (2007) | 10.1103/PhysRevA.75.052307 | null | quant-ph | null | Recently, there have been a number of works investigating the entanglement
properties of distinct noncomplementary parts of discrete and continuous
Bosonic systems in ground and thermal states. The Fermionic case, however, has
yet to be expressly addressed. In this paper we investigate the entanglement
between a pair of far-apart regions of the 3+1 dimensional massless Dirac
vacuum via a previously introduced distillation protocol [B. Reznik et al.,
Phys. Rev. A 71, 042104 (2005)]. We show that entanglement persists over
arbitrary distances, and that as a function of L/R, where L is the distance
between the regions and R is their typical scale, it decays no faster than
exp(-(L/R)^2). We discuss the similarities and differences with analogous
results obtained for the massless Klein-Gordon vacuum.
| [
{
"version": "v1",
"created": "Wed, 27 Sep 2006 13:59:04 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Silman",
"J.",
""
],
[
"Reznik",
"B.",
""
]
]
|
quant-ph/0609213 | Mark Walton | Mark A. Walton | Wigner functions, contact interactions, and matching | 20 pages, no figures | Ann. Phys.322:2233-2248, 2007 | 10.1016/j.aop.2006.11.015 | null | quant-ph | null | Quantum mechanics in phase space (or deformation quantization) appears to
fail as an autonomous quantum method when infinite potential walls are present.
The stationary physical Wigner functions do not satisfy the normal eigen
equations, the *-eigen equations, unless an ad hoc boundary potential is added
[Dias-Prata]. Alternatively, they satisfy a different, higher-order,
``*-eigen-* equation'', locally, i.e. away from the walls [Kryukov-Walton].
Here we show that this substitute equation can be written in a very simple
form, even in the presence of an additional, arbitrary, but regular potential.
The more general applicability of the -eigen- equation is then demonstrated.
First, using an idea from [Fairlie-Manogue], we extend it to a dynamical
equation describing time evolution. We then show that also for general contact
interactions, the -eigen- equation is satisfied locally. Specifically, we treat
the most general possible (Robin) boundary conditions at an infinite wall,
general one-dimensional point interactions, and a finite potential jump.
Finally, we examine a smooth potential, that has simple but different
expressions for x positive and negative. We find that the -eigen- equation is
again satisfied locally. It seems, therefore, that the -eigen- equation is
generally relevant to the matching of Wigner functions; it can be solved
piece-wise and its solutions then matched.
| [
{
"version": "v1",
"created": "Wed, 27 Sep 2006 19:39:10 GMT"
}
]
| 2009-07-17T00:00:00 | [
[
"Walton",
"Mark A.",
""
]
]
|
quant-ph/0609214 | Michael G. Moore | Y. P. Huang, M. G. Moore | Long-distance teleportation of atomic qubit via optical interferometry | null | null | null | null | quant-ph | null | The problem of long-distance teleportation of single-atom qubits via a common
photonic channel is examined within the framework of a Mach-Zender optical
interferometer. As expected, when a coherent state is used as input, a
high-finesse optical cavity is required to overcome sensitivity to spontaneous
emission. However, we find that a number-squeezed light field in a twin-Fock
state can in principle create useful entanglement without cavity-enhancement.
Both approaches require single photon counting detectors, and best results are
obtained by combining cavity-feedback with twin-fock inputs. Such an approach
may allow a fidelity of $.99$ using a two-photon input and currently available
mirror and detector technology. In addition, the present approach can be
conveniently extended to generate multi-site entanglement and entanglement
swapping, both of which are necessities in quantum networks.
| [
{
"version": "v1",
"created": "Wed, 27 Sep 2006 20:51:22 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Huang",
"Y. P.",
""
],
[
"Moore",
"M. G.",
""
]
]
|
quant-ph/0609215 | Alex Kuzmich | T. Chaneliere, D. N. Matsukevich, S. D. Jenkins, S.-Y. Lan, R. Zhao,
T. A. B. Kennedy, and A. Kuzmich | Quantum interference of electromagnetic fields from remote quantum
memories | 4 pages, 3 figures | Physical Review Letters 98, 113602 (2007) | 10.1103/PhysRevLett.98.113602 | null | quant-ph | null | We observe quantum, Hong-Ou-Mandel, interference of fields produced by two
remote atomic memories. High-visibility interference is obtained by utilizing
the finite atomic memory time in four-photon delayed coincidence measurements.
Interference of fields from remote atomic memories is a crucial element in
protocols for scalable generation of multi-node remote qubit entanglement.
| [
{
"version": "v1",
"created": "Wed, 27 Sep 2006 21:43:08 GMT"
}
]
| 2015-06-26T00:00:00 | [
[
"Chaneliere",
"T.",
""
],
[
"Matsukevich",
"D. N.",
""
],
[
"Jenkins",
"S. D.",
""
],
[
"Lan",
"S. -Y.",
""
],
[
"Zhao",
"R.",
""
],
[
"Kennedy",
"T. A. B.",
""
],
[
"Kuzmich",
"A.",
""
]
]
|
quant-ph/0609216 | Rolando Somma | Rolando D. Somma, Cristian D. Batista, Gerardo Ortiz | A Quantum Approach to Classical Statistical Mechanics | 4 pages, no figures | null | 10.1103/PhysRevLett.99.030603 | null | quant-ph cond-mat.other cond-mat.stat-mech q-bio.OT | null | We present a new approach to study the thermodynamic properties of
$d$-dimensional classical systems by reducing the problem to the computation of
ground state properties of a $d$-dimensional quantum model. This
classical-to-quantum mapping allows us to deal with standard optimization
methods, such as simulated and quantum annealing, on an equal basis.
Consequently, we extend the quantum annealing method to simulate classical
systems at finite temperatures. Using the adiabatic theorem of quantum
mechanics, we derive the rates to assure convergence to the optimal
thermodynamic state. For simulated and quantum annealing, we obtain the
asymptotic rates of $T(t) \approx (p N) /(k_B \log t)$ and $\gamma(t) \approx
(Nt)^{-\bar{c}/N}$, for the temperature and magnetic field, respectively. Other
annealing strategies, as well as their potential speed-up, are also discussed.
| [
{
"version": "v1",
"created": "Wed, 27 Sep 2006 22:07:00 GMT"
},
{
"version": "v2",
"created": "Wed, 11 Oct 2006 17:15:08 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Somma",
"Rolando D.",
""
],
[
"Batista",
"Cristian D.",
""
],
[
"Ortiz",
"Gerardo",
""
]
]
|
quant-ph/0609217 | Kazuya Yuasa | Kazuya Yuasa, Hiromichi Nakazato | Resonant Scattering Can Enhance the Degree of Entanglement | 7 pages, 13 figures | J. Phys. A 40 (2007) 297-308 | 10.1088/1751-8113/40/2/009 | null | quant-ph | null | Generation of entanglement between two qubits by scattering an entanglement
mediator is discussed. The mediator bounces between the two qubits and exhibits
a resonant scattering. It is clarified how the degree of the entanglement is
enhanced by the constructive interference of such bouncing processes. Maximally
entangled states are available via adjusting the incident momentum of the
mediator or the distance between the two qubits, but their fine tunings are not
necessarily required to gain highly entangled states and a robust generation of
entanglement is possible.
| [
{
"version": "v1",
"created": "Thu, 28 Sep 2006 01:30:39 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Yuasa",
"Kazuya",
""
],
[
"Nakazato",
"Hiromichi",
""
]
]
|
quant-ph/0609218 | Tokishiro Karasawa | M. Hotta, T. Karasawa, and M. Ozawa | N-body-extended Channel Estimation for Low-Noise Parameters | 10 pages, 1 figure | J. Phys. A: Math. Gen. 39 No 46 (17 November 2006) 14465-14470 | 10.1088/0305-4470/39/46/015 | null | quant-ph | null | The notion of low-noise channels was recently proposed and analyzed in detail
in order to describe noise-processes driven by environment [M. Hotta, T.
Karasawa and M. Ozawa, Phys. Rev. A72, 052334 (2005)]. An estimation theory of
low-noise parameters of channels has also been developed. In this report, we
address the low-noise parameter estimation problem for the $N$-body extension
of low-noise channels. We perturbatively calculate the Fisher information of
the output states in order to evaluate the lower-bound of the mean-square error
of the parameter estimation. We show that the maximum of the Fisher information
over all input states can be attained by a factorized input state in the
leading order of the low-noise parameter. Thus, to achieve optimal estimation,
it is not necessary for there to be entanglement of the $N$ subsystems, as long
as the true low-noise parameter is sufficiently small.
| [
{
"version": "v1",
"created": "Thu, 28 Sep 2006 05:06:16 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Hotta",
"M.",
""
],
[
"Karasawa",
"T.",
""
],
[
"Ozawa",
"M.",
""
]
]
|
quant-ph/0609219 | Zafar Ahmed | Zafar Ahmed | Eigenvalue problems for the complex PT-symmetric potential V(x)= igx | no figures, 9 pages | null | 10.1016/j.physleta.2006.11.057 | null | quant-ph | null | The spectrum of complex PT-symmetric potential, $V(x)=igx$, is known to be
null. We enclose this potential in a hard-box: $V(|x| \ge 1) =\infty $ and in a
soft-box: $V(|x|\ge 1)=0$. In the former case, we find real discrete spectrum
and the exceptional points of the potential. The asymptotic eigenvalues behave
as $E_n \sim n^2.$ The solvable purely imaginary PT-symmetric potentials
vanishing asymptotically known so far do not have real discrete spectrum. Our
solvable soft-box potential possesses two real negative discrete eigenvalues if
$|g|<(1.22330447)$. The soft-box potential turns out to be a scattering
potential not possessing reflectionless states.
| [
{
"version": "v1",
"created": "Thu, 28 Sep 2006 10:25:45 GMT"
},
{
"version": "v2",
"created": "Tue, 21 Nov 2006 19:35:24 GMT"
}
]
| 2015-06-26T00:00:00 | [
[
"Ahmed",
"Zafar",
""
]
]
|
quant-ph/0609220 | Massoud Amini | Massoud Amini, Mehrdad Kalantar, Mahmood M. Roozbehani | Hidden Subhypergroup Problem | part of a technical report to IPM, Tehran | null | null | 84430017 | quant-ph | null | The Hidden Subgroup Problem is used in many quantum algorithms such as
Simon's algorithm and Shor's factoring and discrete log algorithms. A
polynomial time solution is known in case of abelian groups, and normal
subgroups of arbitrary finite groups. The general case is still open. An
efficient solution of the problem for symmetric group $S_n$ would give rise to
an efficient quantum algorithm for Graph Isomorphism Problem. We formulate a
hidden sub-hypergroup problem for finite hypergroups and solve it for finite
commutative hypergroups. The given algorithm is efficient if the corresponding
QFT could be calculated efficiently.
| [
{
"version": "v1",
"created": "Thu, 28 Sep 2006 10:41:21 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Amini",
"Massoud",
""
],
[
"Kalantar",
"Mehrdad",
""
],
[
"Roozbehani",
"Mahmood M.",
""
]
]
|
quant-ph/0609221 | Steffen Trimper | Michael Schulz, Steffen Trimper | Persistence of Quantum Information | 5 pages | null | 10.1016/j.physleta.2007.04.026 | null | quant-ph | null | There is an increasing interest in the role of macroscopic environments to
our understanding of the basics of quantum theory. The knowledge of the
implications of the quantum theory to other theories, especially to the
statistical mechanics and the domain of validity has captivated scientists from
the beginning of quantum description. In such a context, the presence of an
environment is commonly thought as entanglement, decohering and mixing
properties of quantum system. Generically, an environment is assumed to be a
noisy reservoir or a heat bath. Whereas in common interpretation of statistical
mechanics the heat bath is unspecified, in quantum systems a heat bath can also
provide an indirect interaction between otherwise totally decoupled subsystems
and consequently a means to entangle them \cite{cdkl,dvclp,bfp}. In simple
example for the entanglement between two qubits due to the interaction with a
common heat bath has been explicitly shown in \cite{b}. Whereas in that paper
the bath is described by a collection of harmonic oscillators, it seems to be
more reasonable to specify the bath by stochastic forces represented by
stochastic fields. From a more general point of view we expect the bath should
be better described in a stochastic manner and not by deterministic forces. In
the present paper we consider a two level system (qubits) which are able to
perform flip processes by a coupling to classical stochastic fields. Thus we
bridge the gap between quantum and classical probability theory. This problem
is related to many other questions of quantum optics and quantum electronics
where quantum statistical aspects arising from the intrinsic quantum character
of the system while the possible time-dependence of system parameters may be
interpreted as the influence of classical thermal fluctuations.
| [
{
"version": "v1",
"created": "Thu, 28 Sep 2006 11:01:49 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Schulz",
"Michael",
""
],
[
"Trimper",
"Steffen",
""
]
]
|
quant-ph/0609222 | Pochung Chen | Pochung Chen | Dynamical decoupling induced renormalization of the non-Markovian
dynamics | null | Phys. Rev. A 75, 062301 (2007) | 10.1103/PhysRevA.75.062301 | null | quant-ph | null | In this work we develop a numerical framework to investigate the
renormalization of the non-Markovian dynamics of an open quantum system to
which dynamical decoupling is applied. We utilize a non-Markovian master
equation which is derived from the non-Markovian quantum trajectories
formalism. It contains incoherent Markovian dynamics and coherent Schr\"odinger
dynamics as its limiting cases and is capable of capture the transition between
them. We have performed comprehensive simulations for the cases in which the
system is either driven by the Ornstein-Uhlenbeck noise or or is described by
the spin-boson model. The renormalized dynamics under bang-bang control and
continuous dynamical decoupling are simulated. Our results indicate that the
renormalization of the non-Markovian dynamics depends crucially on the spectral
density of the environment and the envelop of the decoupling pulses. The
framework developed in this work hence provides an unified approach to
investigate the efficiency of realistic decoupling pulses. This work also opens
a way to further optimize the decoupling via pulse shaping.
| [
{
"version": "v1",
"created": "Thu, 28 Sep 2006 12:53:11 GMT"
}
]
| 2007-06-13T00:00:00 | [
[
"Chen",
"Pochung",
""
]
]
|
quant-ph/0609223 | Jesus Urias | Jes\'us Ur\'ias | Pure entangled states probed by multipartite Bell experiments | Submitted to Physical Review A | null | null | null | quant-ph | null | The spectral decomposition of all (n,2,2) Bell operators ($2^{2^n}$ in
number, $n \ge 2$), as introduced by Werner and Wolf, is done. Its implications
on the characterization of Bell operators as probes of entanglement are
considered in detail.
| [
{
"version": "v1",
"created": "Thu, 28 Sep 2006 16:44:29 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Urías",
"Jesús",
""
]
]
|
quant-ph/0609224 | Patrick Leung | P. M. Leung and T. C. Ralph | Improving the Fidelity of Optical Zeno Gates via Distillation | 6 pages, 11 figures, Submitted to PRA | null | 10.1103/PhysRevA.74.062325 | null | quant-ph | null | We have modelled the Zeno effect Control-Sign gate of Franson et al (PRA 70,
062302, 2004) and shown that high two-photon to one-photon absorption ratios,
$\kappa$, are needed for high fidelity free standing operation. Hence we
instead employ this gate for cluster state fusion, where the requirement for
$\kappa$ is less restrictive. With the help of partially offline one-photon and
two-photon distillations, we can achieve a fusion gate with unity fidelity but
non-unit probability of success. We conclude that for $\kappa > 2200$, the Zeno
fusion gate will out perform the equivalent linear optics gate.
| [
{
"version": "v1",
"created": "Fri, 29 Sep 2006 04:20:16 GMT"
}
]
| 2015-06-26T00:00:00 | [
[
"Leung",
"P. M.",
""
],
[
"Ralph",
"T. C.",
""
]
]
|
quant-ph/0609225 | Mattias Johnsson | Mattias T. Johnsson and Simon A. Haine | Generating squeezing in an atom laser through self-interaction | v2. Incorporates changes due to referees' comments. We also
demonstrate that our scheme generates number squeezing as well as quadrature
squeezing | Phys. Rev. Lett. 99, 010401 (2007) | 10.1103/PhysRevLett.99.010401 | null | quant-ph cond-mat.other | null | We describe a scheme for creating quadrature- and intensity-squeezed atom
lasers that do not require squeezed light as an input. The beam becomes
squeezed due to nonlinear interactions between the atoms in the beam in an
analogue to optical Kerr squeezing. We develop an analytic model of the process
which we compare to a detailed stochastic simulation of the system using phase
space methods. Finally we show that significant squeezing can be obtained in an
experimentally realistic system and suggest ways of increasing the tunability
of the squeezing.
| [
{
"version": "v1",
"created": "Fri, 29 Sep 2006 06:49:47 GMT"
},
{
"version": "v2",
"created": "Thu, 12 Jul 2007 03:34:30 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Johnsson",
"Mattias T.",
""
],
[
"Haine",
"Simon A.",
""
]
]
|
quant-ph/0609226 | Debasis Sarkar | Indrani Chattopadhyay and Debasis Sarkar | General Classes of Impossible Operations through the Existence of
Incomparable States | 13 pages, Latex, to appear in Quantum Information and Computation | Quantum Information and Computation, 7 (2007) 392-400 | null | null | quant-ph | null | In this work we show that the most general class of anti-unitary operators
are nonphysical in nature through the existence of incomparable pure bipartite
entangled states. It is also shown that a large class of
inner-product-preserving operations defined only on the three qubits having
spin-directions along x, y and z are impossible. If we perform such an
operation locally on a particular pure bipartite state then it will exactly
transform to another pure bipartite state that is incomparable with the
original one. As subcases of the above results we find the nonphysical nature
of universal exact flipping operation and existence of universal Hadamard gate.
Beyond the information conservation in terms of entanglement, this work shows
how an impossible local operation evolve with the joint system in a nonphysical
way.
| [
{
"version": "v1",
"created": "Fri, 29 Sep 2006 08:54:40 GMT"
}
]
| 2007-11-04T00:00:00 | [
[
"Chattopadhyay",
"Indrani",
""
],
[
"Sarkar",
"Debasis",
""
]
]
|
quant-ph/0609227 | Michael Duff | M. J. Duff and S. Ferrara | E_7 and the tripartite entanglement of seven qubits | Minor improvements. 15 page latex | Phys.Rev.D76:025018,2007 | 10.1103/PhysRevD.76.025018 | Imperial/TP/2006/mjd/5 and CERN-PH-TH/2006-194 | quant-ph gr-qc hep-th | null | In quantum information theory, it is well known that the tripartite
entanglement of three qubits is described by the group [SL(2,C)]^3 and that the
entanglement measure is given by Cayley's hyperdeterminant. This has provided
an analogy with certain N=2 supersymmetric black holes in string theory, whose
entropy is also given by the hyperdeterminant. In this paper, we extend the
analogy to N=8. We propose that a particular tripartite entanglement of seven
qubits, encoded in the Fano plane, is described by the exceptional group E_7(C)
and that the entanglement measure is given by Cartan's quartic E_7 invariant.
| [
{
"version": "v1",
"created": "Fri, 29 Sep 2006 10:16:41 GMT"
},
{
"version": "v2",
"created": "Tue, 31 Oct 2006 16:44:46 GMT"
},
{
"version": "v3",
"created": "Wed, 2 May 2007 17:01:57 GMT"
},
{
"version": "v4",
"created": "Tue, 9 Oct 2007 18:45:59 GMT"
}
]
| 2008-11-26T00:00:00 | [
[
"Duff",
"M. J.",
""
],
[
"Ferrara",
"S.",
""
]
]
|
quant-ph/0609228 | Christian Roos | M. Riebe, K. Kim, P. Schindler, T. Monz, P. O. Schmidt, T. K. Koerber,
W. Haensel, H. Haeffner, C. F. Roos, R. Blatt | Process tomography of ion trap quantum gates | null | Phys. Rev. Lett. 97, 220407 (2006) | 10.1103/PhysRevLett.97.220407 | null | quant-ph | null | A crucial building block for quantum information processing with trapped ions
is a controlled-NOT quantum gate. In this paper, two different sequences of
laser pulses implementing such a gate operation are analyzed using quantum
process tomography. Fidelities of up to 92.6(6)% are achieved for single gate
operations and up to 83.4(8)% for two concatenated gate operations. By process
tomography we assess the performance of the gates for different experimental
realizations and demonstrate the advantage of amplitude--shaped laser pulses
over simple square pulses. We also investigate whether the performance of
concatenated gates can be inferred from the analysis of the single gates.
| [
{
"version": "v1",
"created": "Fri, 29 Sep 2006 10:20:18 GMT"
}
]
| 2009-01-15T00:00:00 | [
[
"Riebe",
"M.",
""
],
[
"Kim",
"K.",
""
],
[
"Schindler",
"P.",
""
],
[
"Monz",
"T.",
""
],
[
"Schmidt",
"P. O.",
""
],
[
"Koerber",
"T. K.",
""
],
[
"Haensel",
"W.",
""
],
[
"Haeffner",
"H.",
""
],
[
"Roos",
"C. F.",
""
],
[
"Blatt",
"R.",
""
]
]
|
quant-ph/0609229 | Igor Bjelakovic | Igor Bjelakovic, Holger Boche | Ergodic Classical-Quantum Channels: Structure and Coding Theorems | 19 pages, no figures. Final version | IEEE Transactions on Information Theory Vol. 54, No. 2, pp.
723-742, February 2008 | 10.1109/TIT.2007.913232 | null | quant-ph cs.IT math-ph math.IT math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider ergodic causal classical-quantum channels (cq-channels) which
additionally have a decaying input memory. In the first part we develop some
structural properties of ergodic cq-channels and provide equivalent conditions
for ergodicity. In the second part we prove the coding theorem with weak
converse for causal ergodic cq-channels with decaying input memory. Our proof
is based on the possibility to introduce joint input-output state for the
cq-channels and an application of the Shannon-McMillan theorem for ergodic
quantum states. In the last part of the paper it is shown how this result
implies coding theorem for the classical capacity of a class of causal ergodic
quantum channels.
| [
{
"version": "v1",
"created": "Fri, 29 Sep 2006 11:35:07 GMT"
},
{
"version": "v2",
"created": "Mon, 16 Feb 2009 11:52:46 GMT"
}
]
| 2016-11-18T00:00:00 | [
[
"Bjelakovic",
"Igor",
""
],
[
"Boche",
"Holger",
""
]
]
|
quant-ph/0609230 | Sara Felloni | Sara Felloni and Giuliano Strini | A Graphic Representation of States for Quantum Copying Machines | 30 pages, 22 figures | Electronic Journal of Theoretical Physics - EJTP 3, No. 11 (2006)
159-187 | null | null | quant-ph | null | The aim of this paper is to introduce a new graphic representation of quantum
states by means of a specific application: the analysis of two models of
quantum copying machines. The graphic representation by diagrams of states
offers a clear and detailed visualization of quantum information's flow during
the unitary evolution of not too complex systems. The diagrams of states are
exponentially more complex in respect to the standard representation and this
clearly illustrates the discrepancy of computational power between quantum and
classical systems. After a brief introductive exposure of the general theory,
we present a constructive procedure to illustrate the new representation by
means of concrete examples. Elementary diagrams of states for single-qubit and
two-qubit systems and a simple scheme to represent entangled states are
presented. Quantum copying machines as imperfect cloners of quantum states are
introduced and the quantum copying machines of Griffiths and Niu and of Buzek
and Hillery are analyzed, determining quantum circuits of easier
interpretation. The method has indeed shown itself to be extremely successful
for the representation of the involved quantum operations and it has allowed to
point out the characteristic aspects of the quantum computations examined.
| [
{
"version": "v1",
"created": "Fri, 29 Sep 2006 13:16:47 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Felloni",
"Sara",
""
],
[
"Strini",
"Giuliano",
""
]
]
|
quant-ph/0609231 | Harun Egrifes | Harun Egrifes, Ramazan Sever | Bound-state solutions of the Klein-Gordon equation for the generalized
PT-symmetric Hulthen potential | 23 pages including 2 figures and 1 table. To appear in International
Journal of Theoretical Physics | Int. J. Theo. Phys. 46, 935(2007) | null | null | quant-ph | null | The one-dimensional Klein-Gordon equation is solved for the PT-symmetric
generalized Hulthen potential in the scalar coupling scheme. The relativistic
bound-state energy spectrum and the corresponding wave functions are obtained
by using the Nikiforov-Uvarov method which is based on solving the second-order
linear differential equations by reduction to a generalized equation of
hypergeometric type.
| [
{
"version": "v1",
"created": "Fri, 29 Sep 2006 13:42:13 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Egrifes",
"Harun",
""
],
[
"Sever",
"Ramazan",
""
]
]
|
quant-ph/0609232 | Bing He | Bing He, J\'anos A. Bergou and Zhiyong Wang | Implementation of quantum operations on single photon qudits | 4 pages, 3 figures | Phys. Rev. A 76, 042326 (2007) | 10.1103/PhysRevA.76.042326 | null | quant-ph | null | We show that a general linear transformation from one single photon qudit to
another, the dimension of which can be either equal or unequal to that of the
first one, can be implemented by linear optics. As an application of the scheme
we elaborate a method to deterministically realize any finite-element Positive
Operator Value Measure (POVM) on single photon signals, which is also
generalizable to any quantum system in principle.
| [
{
"version": "v1",
"created": "Fri, 29 Sep 2006 16:58:39 GMT"
},
{
"version": "v2",
"created": "Sat, 30 Sep 2006 05:40:12 GMT"
},
{
"version": "v3",
"created": "Fri, 20 Oct 2006 17:11:38 GMT"
},
{
"version": "v4",
"created": "Wed, 25 Oct 2006 22:39:56 GMT"
},
{
"version": "v5",
"created": "Sat, 24 Feb 2007 19:19:45 GMT"
},
{
"version": "v6",
"created": "Thu, 5 Apr 2007 16:38:53 GMT"
},
{
"version": "v7",
"created": "Sat, 2 Jun 2007 04:23:49 GMT"
}
]
| 2007-10-22T00:00:00 | [
[
"He",
"Bing",
""
],
[
"Bergou",
"János A.",
""
],
[
"Wang",
"Zhiyong",
""
]
]
|
quant-ph/0609233 | Paolo Amore Dr | Paolo Amore, Francisco M. Fernandez | On Dalgarno and Lewis Perturbation Theory for Scattering States | 10 pages, 2 figures | null | 10.1016/j.physleta.2007.03.031 | null | quant-ph | null | We apply the method of Dalgarno and Lewis to scattering states and discuss
the choice of the unperturbed model in order to have a convergent perturbation
series for the phase shift.
| [
{
"version": "v1",
"created": "Fri, 29 Sep 2006 15:16:02 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Amore",
"Paolo",
""
],
[
"Fernandez",
"Francisco M.",
""
]
]
|
quant-ph/0609234 | J\'er\'emie Roland | Olga Lopez Acevedo, J\'er\'emie Roland and Nicolas J. Cerf | Exploring scalar quantum walks on Cayley graphs | 9 pages, 4 figures | Quantum Information & Computation, 8(1&2):68-81, 2008. | null | null | quant-ph | null | A quantum walk, \emph{i.e.}, the quantum evolution of a particle on a graph,
is termed \emph{scalar} if the internal space of the moving particle (often
called the coin) has a dimension one. Here, we study the existence of scalar
quantum walks on Cayley graphs, which are built from the generators of a group.
After deriving a necessary condition on these generators for the existence of a
scalar quantum walk, we present a general method to express the evolution
operator of the walk, assuming homogeneity of the evolution. We use this
necessary condition and the subsequent constructive method to investigate the
existence of scalar quantum walks on Cayley graphs of various groups presented
with two or three generators. In this restricted framework, we classify all
groups -- in terms of relations between their generators -- that admit scalar
quantum walks, and we also derive the form of the most general evolution
operator. Finally, we point out some interesting special cases, and extend our
study to a few examples of Cayley graphs built with more than three generators.
| [
{
"version": "v1",
"created": "Fri, 29 Sep 2006 15:58:28 GMT"
},
{
"version": "v2",
"created": "Sat, 30 Sep 2006 07:12:15 GMT"
}
]
| 2007-11-27T00:00:00 | [
[
"Acevedo",
"Olga Lopez",
""
],
[
"Roland",
"Jérémie",
""
],
[
"Cerf",
"Nicolas J.",
""
]
]
|
quant-ph/0609235 | Andriy Lyakhov | A. O. Lyakhov and C. Bruder | Use of dynamical coupling for improved quantum state transfer | 5 pages, 7 figures | Phys. Rev. B 74, 235303 (2006) | 10.1103/PhysRevB.74.235303 | null | quant-ph | null | We propose a method to improve quantum state transfer in transmission lines.
The idea is to localize the information on the last qubit of a transmission
line, by dynamically varying the coupling constants between the first and the
last pair of qubits. The fidelity of state transfer is higher then in a chain
with fixed coupling constants. The effect is stable against small fluctuations
in the system parameters.
| [
{
"version": "v1",
"created": "Fri, 29 Sep 2006 17:36:17 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Lyakhov",
"A. O.",
""
],
[
"Bruder",
"C.",
""
]
]
|
quant-ph/0609236 | J. M. Taylor | L. Jiang, J. M. Taylor, M. D. Lukin | A fast and robust approach to long-distance quantum communication with
atomic ensembles | 10 pages, 4 figures, 5 tables (Two appendixes are added to justify
two claims used in the maintext.) | Phys. Rev. A 76, 012301 (2007) | 10.1103/PhysRevA.76.012301 | null | quant-ph | null | Quantum repeaters create long-distance entanglement between quantum systems
while overcoming difficulties such as the attenuation of single photons in a
fiber. Recently, an implementation of a repeater protocol based on single
qubits in atomic ensembles and linear optics has been proposed [Nature 414, 413
(2001)]. Motivated by rapid experimental progress towards implementing that
protocol, here we develop a more efficient scheme compatible with active
purification of arbitrary errors. Using similar resources as the earlier
protocol, our approach intrinsically purifies leakage out of the logical
subspace and all errors within the logical subspace, leading to greatly
improved performance in the presence of experimental inefficiencies. Our
analysis indicates that our scheme could generate approximately one pair per 3
minutes over 1280 km distance with fidelity (F>78%) sufficient to violate
Bell's inequality.
| [
{
"version": "v1",
"created": "Fri, 29 Sep 2006 17:37:07 GMT"
},
{
"version": "v2",
"created": "Thu, 23 Nov 2006 20:23:21 GMT"
},
{
"version": "v3",
"created": "Wed, 4 Apr 2007 01:19:45 GMT"
}
]
| 2007-07-03T00:00:00 | [
[
"Jiang",
"L.",
""
],
[
"Taylor",
"J. M.",
""
],
[
"Lukin",
"M. D.",
""
]
]
|
quant-ph/0609237 | Stephanie Wehner | Harry Buhrman, Matthias Christandl, Patrick Hayden, Hoi-Kwong Lo,
Stephanie Wehner | Security of quantum bit string commitment depends on the information
measure | To appear in PRL. Short version of quant-ph/0504078, long version to
appear separately. Improved security definition and result, one new lemma
that may be of independent interest. v2: added funding reference, no other
changes | Phys. Rev. Lett., 97, 250501 (2006) | 10.1103/PhysRevLett.97.250501 | null | quant-ph | null | Unconditionally secure non-relativistic bit commitment is known to be
impossible in both the classical and the quantum world. However, when
committing to a string of n bits at once, how far can we stretch the quantum
limits? In this letter, we introduce a framework of quantum schemes where Alice
commits a string of n bits to Bob, in such a way that she can only cheat on a
bits and Bob can learn at most b bits of information before the reveal phase.
Our results are two-fold: we show by an explicit construction that in the
traditional approach, where the reveal and guess probabilities form the
security criteria, no good schemes can exist: a+b is at least n. If, however,
we use a more liberal criterion of security, the accessible information, we
construct schemes where a=4 log n+O(1) and b=4, which is impossible
classically. Our findings significantly extend known no-go results for quantum
bit commitment.
| [
{
"version": "v1",
"created": "Fri, 29 Sep 2006 18:02:02 GMT"
},
{
"version": "v2",
"created": "Thu, 9 Nov 2006 13:09:55 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Buhrman",
"Harry",
""
],
[
"Christandl",
"Matthias",
""
],
[
"Hayden",
"Patrick",
""
],
[
"Lo",
"Hoi-Kwong",
""
],
[
"Wehner",
"Stephanie",
""
]
]
|
quant-ph/0610001 | Pankaj Agrawal | Pankaj Agrawal and Arun Pati | Perfect Teleportation and Superdense Coding With W-States | 9 pages, no figure | null | 10.1103/PhysRevA.74.062320 | null | quant-ph | null | True tripartite entanglement of the state of a system of three qubits can be
classified on the basis of stochastic local operations and classical
communications (SLOCC). Such states can be classified in two categories: GHZ
states and W-states. It is known that GHZ states can be used for teleportation
and superdense coding, but the prototype W-state cannot be. However, we show
that there is a class of W-states that can be used for perfect teleportation
and superdense coding.
| [
{
"version": "v1",
"created": "Sat, 30 Sep 2006 07:05:11 GMT"
}
]
| 2015-06-26T00:00:00 | [
[
"Agrawal",
"Pankaj",
""
],
[
"Pati",
"Arun",
""
]
]
|
quant-ph/0610002 | Gennadiy Filippov | G.M. Filippov | New perturbation theory in QED | 17 pages, no figures, reported at 2-nd Int.Conf. on quantum
electrodynamics and statistical physics QEDSP2006 (19-23 Sept.2006, Kharkov,
Ukraine | null | null | null | quant-ph | null | The perturbation theory in QED used the new form of ground state as a state
of interacted particles is proposed. The mean electromagnetic field of charged
elementary particle is calculated. The possibility of elimination the problem
with ultraviolet as well as infrared divergences is shown. The electromagnetic
energy of the particle turns out to be regular and small.
| [
{
"version": "v1",
"created": "Sun, 1 Oct 2006 21:09:43 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Filippov",
"G. M.",
""
]
]
|
quant-ph/0610003 | Nilanjana Datta | Garry Bowen and Nilanjana Datta | Quantum Coding Theorems for Arbitrary Sources, Channels and Entanglement
Resources | null | null | null | null | quant-ph | null | The information spectrum approach gives general formulae for optimal rates of
various information theoretic protocols, under minimal assumptions on the
nature of the sources, channels and entanglement resources involved. This paper
culminates in the derivation of the dense coding capacity for a noiseless
quantum channel, assisted by arbitrary shared entanglement, using this
approach. We also review the currently known coding theorems, and their
converses, for protocols such as data compression for arbitrary quantum sources
and transmission of classical information through arbitrary quantum channels.
In addition, we derive the optimal rate of data compression for a mixed source
| [
{
"version": "v1",
"created": "Sat, 30 Sep 2006 12:26:14 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Bowen",
"Garry",
""
],
[
"Datta",
"Nilanjana",
""
]
]
|
quant-ph/0610004 | Benjamin Greenbaum | Benjamin D. Greenbaum, Salman Habib, Kosuke Shizume, and Bala Sundaram | Semiclassics of the Chaotic Quantum-Classical Transition | 16 pages, 7 Figures, Submitted to Phys Rev E | Phys. Rev. E 76, 046215 (2007) | 10.1103/PhysRevE.76.046215 | null | quant-ph nlin.CD | null | We elucidate the basic physical mechanisms responsible for the
quantum-classical transition in one-dimensional, bounded chaotic systems
subject to unconditioned environmental interactions. We show that such a
transition occurs due to the dual role of noise in regularizing the
semiclassical Wigner function and averaging over fine structures in classical
phase space. The results are interpreted in the novel context of applying
recent advances in the theory of measurement and open systems to the
semiclassical quantum regime. We use these methods to show how a local
semiclassical picture is stabilized and can then be approximated by a classical
distribution at later times. The general results are demonstrated explicitly
via high-resolution numerical simulations of the quantum master equation for a
chaotic Duffing oscillator.
| [
{
"version": "v1",
"created": "Sat, 30 Sep 2006 15:18:50 GMT"
},
{
"version": "v2",
"created": "Wed, 4 Apr 2007 19:37:18 GMT"
},
{
"version": "v3",
"created": "Wed, 22 Aug 2007 16:31:27 GMT"
}
]
| 2007-10-18T00:00:00 | [
[
"Greenbaum",
"Benjamin D.",
""
],
[
"Habib",
"Salman",
""
],
[
"Shizume",
"Kosuke",
""
],
[
"Sundaram",
"Bala",
""
]
]
|
quant-ph/0610005 | Qi-Ren Zhang | Qi-Ren Zhang | A General Information Theoretical Proof for the Second Law of
Thermodynamics | 4 pages | Int. J. Mod. Phys. E17(2008) 531-537 | 10.1142/S0218301308009859 | null | quant-ph cond-mat.stat-mech | null | We show that the conservation and the non-additivity of the information,
together with the additivity of the entropy make the entropy increase in an
isolated system. The collapse of the entangled quantum state offers an example
of the information non-additivity. Nevertheless, the later is also true in
other fields, in which the interaction information is important. Examples are
classical statistical mechanics, social statistics and financial processes. The
second law of thermodynamics is thus proven in its most general form. It is
exactly true, not only in quantum and classical physics but also in other
processes, in which the information is conservative and non-additive.
| [
{
"version": "v1",
"created": "Sun, 1 Oct 2006 08:26:08 GMT"
},
{
"version": "v2",
"created": "Wed, 28 Mar 2007 09:57:31 GMT"
},
{
"version": "v3",
"created": "Thu, 29 Mar 2007 02:05:14 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Zhang",
"Qi-Ren",
""
]
]
|
quant-ph/0610006 | Stefano Mancini | Stefano Mancini and Howard M. Wiseman | Optimal control of entanglement via quantum feedback | 10 pages, 5 figures | Phys. Rev. A 75, 012330 (2007). | 10.1103/PhysRevA.75.012330 | null | quant-ph | null | It has recently been shown that finding the optimal measurement on the
environment for stationary Linear Quadratic Gaussian control problems is a
semi-definite program. We apply this technique to the control of the
EPR-correlations between two bosonic modes interacting via a parametric
Hamiltonian at steady state. The optimal measurement turns out to be nonlocal
homodyne measurement -- the outputs of the two modes must be combined before
measurement. We also find the optimal local measurement and control technique.
This gives the same degree of entanglement but a higher degree of purity than
the local technique previously considered [S. Mancini, Phys. Rev. A {\bf 73},
010304(R) (2006)].
| [
{
"version": "v1",
"created": "Sun, 1 Oct 2006 08:57:41 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Mancini",
"Stefano",
""
],
[
"Wiseman",
"Howard M.",
""
]
]
|
quant-ph/0610007 | Charis Anastopoulos | C. Anastopoulos, S. Shresta, B. L. Hu | Quantum Entanglement under Non-Markovian Dynamics of Two Qubits
Interacting with a common Electromagnetic Field | 37 pages, revTex, 4 figs. Added a new subsection in the derivation of
the master equation and one explaining the origin and significance of the
non-Markovian behavior. Also a new appendix giving the time-dependent terms
in the master equation | null | null | null | quant-ph | null | We study the non-equilibrium dynamics of a pair of qubits made of two-level
atoms separated in space with distance r and interacting with one common
electromagnetic field but not directly with each other. Our calculation makes a
weak coupling assumption, but no Born or Markov approximation. We derived a
non-Markovian master equation for the evolution of the reduced density matrix
of the two-qubit system after integrating out the electromagnetic field modes.
It contains a Markovian part with a Lindblad type operator and a nonMarkovian
contribution, the physics of which is the main focus of this study. We use the
concurrence function as a measure of quantum entanglement between the two
qubits. Two classes of states are studied in detail: Class A is a one parameter
family of states which are the superposition of the highest energy and Class B
states are linear combinations of the symmetric and the antisymmetric Bell
states. We obtain similar behavior for the Bell states as in earlier results
derived by using the Born-Markov approximation. However, in the Class A states
the behavior is qualitatively different: under the non-Markovian evolution we
do not see sudden death of quantum entanglement and subsequent revivals, except
when the qubits are sufficiently far apart. We provide explanations for such
differences of behavior both between these two classes of states and between
the predictions from the Markov and non-Markovian dynamics. We also study the
decoherence of this two-qubit system and find that the decoherence rate in the
case of one qubit initially in an excited state does not change significantly
with the qubits separation whereas it does for the case when one qubit is
initially in the ground state.
| [
{
"version": "v1",
"created": "Sun, 1 Oct 2006 18:44:49 GMT"
},
{
"version": "v2",
"created": "Wed, 31 Jan 2007 15:36:49 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Anastopoulos",
"C.",
""
],
[
"Shresta",
"S.",
""
],
[
"Hu",
"B. L.",
""
]
]
|
quant-ph/0610008 | Robert Alicki | Robert Alicki | Quantumness of Josephson junctions reexamined | 8 pages, added new test of quantumness | null | null | null | quant-ph | null | There exists an increasing evidence supporting the picture of the Josephson
junction (JJ) as a "macroscopic quantum system". On the other hand the
interpretation of experimental data strongly depends on the assumed theoretical
model. We analyse the possible states of a Cooper pair box ("charge qubit") for
the two types of models : two-mode Bose-Hubbard model with its large $N$
aproximations and the many-body description within the mean-field approximation
(Gross-Pitaevski equation). While the first class of models supports the
picture of JJ being a quantum subsystem of a single degree of freedom, the
second approach yields an essentially classical structure of accessible quantum
states which, in particular, implies the absence of entanglement for two
coupled JJ's. The arguments in favor of the mean-field theory are presented and
different experimental tests including a new proposal are briefly discussed.
| [
{
"version": "v1",
"created": "Sun, 1 Oct 2006 19:47:06 GMT"
},
{
"version": "v2",
"created": "Fri, 20 Oct 2006 12:13:01 GMT"
},
{
"version": "v3",
"created": "Thu, 1 Feb 2007 19:26:54 GMT"
},
{
"version": "v4",
"created": "Sat, 16 Jun 2007 17:28:06 GMT"
}
]
| 2007-06-16T00:00:00 | [
[
"Alicki",
"Robert",
""
]
]
|
quant-ph/0610009 | Kazuyuki Fujii | Kazuyuki Fujii (Yokohama City University) and Tatsuo Suzuki (Waseda
University) | On the Magic Matrix by Makhlin and the B-C-H Formula in SO(4) | Latex ; 11 pages ; 1 figure ; minor changes. To appear in
International Journal of Geometric Methods in Modern Physics (vol.4, no.5 or
6), 2007 | Int.J.Geom.Meth.Mod.Phys.4:897-905,2007 | 10.1142/S0219887807002430 | null | quant-ph hep-th math-ph math.MP | null | A closed expression to the Baker-Campbell-Hausdorff (B-C-H) formula in SO(4)
is given by making use of the magic matrix by Makhlin. As far as we know this
is the {\bf first nontrivial example} on (semi-) simple Lie groups summing up
all terms in the B-C-H expansion.
| [
{
"version": "v1",
"created": "Mon, 2 Oct 2006 01:00:43 GMT"
},
{
"version": "v2",
"created": "Tue, 24 Oct 2006 02:16:18 GMT"
},
{
"version": "v3",
"created": "Wed, 18 Jul 2007 23:22:50 GMT"
}
]
| 2008-11-26T00:00:00 | [
[
"Fujii",
"Kazuyuki",
"",
"Yokohama City University"
],
[
"Suzuki",
"Tatsuo",
"",
"Waseda\n University"
]
]
|
quant-ph/0610010 | Neil Budko | Neil V. Budko and Alexander B. Samokhin | Essential state of the electromagnetic field and the double-slit
experiment | 4 pages | null | null | null | quant-ph | null | A new class of generalized solutions related to the essential spectrum of
linear Maxwell's equations is presented. The essential modes are given in terms
of normalized singular Weyl's sequences, whose square represents Dirac's delta
functions in spatial and angular frequency domains. The action integral
associated with essential modes is well-defined. We claim that these modes
represent the collapsed state of the electromagnetic field and, with some
additional assumptions on the conservation of action, are suitable for
describing the double-slit experiment in accordance with the orthodox point of
view.
| [
{
"version": "v1",
"created": "Mon, 2 Oct 2006 10:27:33 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Budko",
"Neil V.",
""
],
[
"Samokhin",
"Alexander B.",
""
]
]
|
quant-ph/0610011 | Marius Grigorescu | M. Grigorescu | Variational Principle for Mixed Classical-Quantum Systems | 16 pages, LaTex; added Figure 2 and Figure 3 | Can. J. Phys. 85 (2007) 1023-1034 | 10.1139/P07-107 | null | quant-ph cond-mat.stat-mech gr-qc | null | An extended variational principle providing the equations of motion for a
system consisting of interacting classical, quasiclassical and quantum
components is presented, and applied to the model of bilinear coupling. The
relevant dynamical variables are expressed in the form of a quantum state
vector which includes the action of the classical subsystem in its phase
factor. It is shown that the statistical ensemble of Brownian state vectors for
a quantum particle in a classical thermal environment can be described by a
density matrix evolving according to a nonlinear quantum Fokker-Planck
equation. Exact solutions of this equation are obtained for a two-level system
in the limit of high temperatures, considering both stationary and
nonstationary initial states. A treatment of the common time shared by the
quantum system and its classical environment, as a collective variable rather
than as a parameter, is presented in the Appendix.
| [
{
"version": "v1",
"created": "Mon, 2 Oct 2006 17:34:31 GMT"
},
{
"version": "v2",
"created": "Thu, 28 Jun 2007 10:45:59 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Grigorescu",
"M.",
""
]
]
|
quant-ph/0610012 | Alexei Taichenachev | A.V. Taichenachev and V.I. Yudin | CPT-like states in an ensemble of interacting fermions. On the
possibility of new mechanism of superconductivity | Revtex 5 pages, including 1 figure; v2 references added and typos
corrected | null | null | null | quant-ph cond-mat.str-el cond-mat.supr-con physics.atom-ph physics.optics | null | Using the standard Hamiltonian of the BCS theory, we show that in an ensemble
of interacting fermions there exists a coherent state $|NC>$, which nullifies
the Hamiltonian of the interparticle interaction. This state has an analogy
with the well-known in quantum optics coherent population trapping effect
(CPT). A possible application of such CPT-like states in the superconductivity
theory is discussed.
| [
{
"version": "v1",
"created": "Tue, 3 Oct 2006 05:38:31 GMT"
},
{
"version": "v2",
"created": "Tue, 10 Oct 2006 12:14:52 GMT"
}
]
| 2016-09-08T00:00:00 | [
[
"Taichenachev",
"A. V.",
""
],
[
"Yudin",
"V. I.",
""
]
]
|
quant-ph/0610013 | Yoshifumi Inui | Yoshifumi Inui | Quantum Property Testing for Solvable Groups | null | null | null | null | quant-ph | null | Property testing has been extensively studied and its target is to determine
whether a given object satisfies a certain property or it is far from the
property. In this paper, we construct an efficient quantum algorithm which
tests if a given quantum oracle performs the group multiplication of a solvable
group. Our work is strongly based on the efficient classical testing algorithm
for Abelian groups proposed by Friedl, Ivanyos and Santha. Since every Abelian
group is a solvable group, our result is in a sense a generalization of their
result.
| [
{
"version": "v1",
"created": "Tue, 3 Oct 2006 10:19:21 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Inui",
"Yoshifumi",
""
]
]
|
quant-ph/0610014 | Minoru Horibe | Minoru Horibe, Akihisa Hayashi and Takaaki Hashimoto | Optimal estimation of an observable's expectation value for pure states
for general measure of deviation | 5 pages, 1 figure | null | null | null | quant-ph | null | We investigate the optimal estimation of quantum expectation value of a
physical observable, which minimizes a mean error with respect to general
measure of deviation, when a finite number of copies of a pure state are
prepared. If pure sates are uniformly distributed, the minimum value of mean
error for any measure of deviation is achieved by projective measurement on
each copy.
| [
{
"version": "v1",
"created": "Tue, 3 Oct 2006 10:42:41 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Horibe",
"Minoru",
""
],
[
"Hayashi",
"Akihisa",
""
],
[
"Hashimoto",
"Takaaki",
""
]
]
|
quant-ph/0610015 | Zhiliang Yuan | Z. L. Yuan, A. W. Sharpe, and A. J. Shields | Unconditionally secure one-way quantum key distribution using decoy
pulses | 10 pages, 5 figures | Appl. Phys. Lett. 90, 011118(2007) | 10.1063/1.2752766 | null | quant-ph | null | We report here a complete experimental realization of one-way decoy-pulse
quantum key distribution, demonstrating an unconditionally secure key rate of
5.51 kbps for a 25.3 km fibre length. This is two orders of magnitudes higher
than the value that can be obtained with a non-decoy system. We introduce also
a simple test for detecting the photon number splitting attack and highlight
that it is essential for the security of the technique to fully characterize
the source and detectors used.
| [
{
"version": "v1",
"created": "Tue, 3 Oct 2006 11:20:51 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Yuan",
"Z. L.",
""
],
[
"Sharpe",
"A. W.",
""
],
[
"Shields",
"A. J.",
""
]
]
|
quant-ph/0610016 | Thierry Dauxois | S\'ebastien Paulin (Phys-ENS), Angel Alastuey (Phys-ENS), Thierry
Dauxois (Phys-ENS) | Analysis of path integrals at low temperature : Box formula, occupation
time and ergodic approximation | null | Journal of Statistical Physics 128, 1391-1414 (2007) | 10.1007/s10955-007-9346-5 | null | quant-ph cond-mat.stat-mech | null | We study the low temperature behaviour of path integrals for a simple
one-dimensional model. Starting from the Feynman-Kac formula, we derive a new
functional representation of the density matrix at finite temperature, in terms
of the occupation times of Brownian motions constrained to stay within boxes
with finite sizes. From that representation, we infer a kind of ergodic
approximation, which only involves double ordinary integrals. As shown by its
applications to different confining potentials, the ergodic approximation turns
out to be quite efficient, especially in the low-temperature regime where other
usual approximations fail.
| [
{
"version": "v1",
"created": "Tue, 3 Oct 2006 13:45:40 GMT"
}
]
| 2016-08-16T00:00:00 | [
[
"Paulin",
"Sébastien",
"",
"Phys-ENS"
],
[
"Alastuey",
"Angel",
"",
"Phys-ENS"
],
[
"Dauxois",
"Thierry",
"",
"Phys-ENS"
]
]
|
quant-ph/0610017 | Gerardo Paz Silva | Gerardo A. Paz-Silva, John H. Reina | A pairwise additive strategy for quantifying multipartite entanglement | 4 pages, new version contains corrected typos. Title changed, proofs
added, new results reported. Additivity revisited | null | null | null | quant-ph | null | Based on the idea of measuring the factorizability of a given density matrix,
we propose a pairwise analysis strategy for quantifying and understanding
multipartite entanglement. The methodology proves very effective as it
immediately guarantees, in addition to the usual entanglement properties,
additivity and strong super additivity. We give a specific set of quantities
that fulfill the protocol and which, according to our numerical calculations,
make the entanglement measure an LOCC non-increasing function. The strategy
allows a redefinition of the structural concept of global entanglement.
| [
{
"version": "v1",
"created": "Tue, 3 Oct 2006 17:22:29 GMT"
},
{
"version": "v2",
"created": "Sat, 7 Oct 2006 01:27:26 GMT"
},
{
"version": "v3",
"created": "Tue, 17 Oct 2006 19:12:52 GMT"
},
{
"version": "v4",
"created": "Wed, 22 Nov 2006 14:25:53 GMT"
},
{
"version": "v5",
"created": "Sat, 3 Feb 2007 01:12:39 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Paz-Silva",
"Gerardo A.",
""
],
[
"Reina",
"John H.",
""
]
]
|
quant-ph/0610018 | Daniel Burgarth | D. Burgarth, V. Giovannetti, S. Bose | Optimal quantum chain communication by end gates | 6 pages, 4 figures; improved version includes discussion on finitely
many gate applications | Phys. Rev. A 75, 062327 (2007) | 10.1103/PhysRevA.75.062327 | null | quant-ph | null | The scalability of solid state quantum computation relies on the ability of
connecting the qubits to the macroscopic world. Quantum chains can be used as
quantum wires to keep regions of external control at a distance. However even
in the absence of external noise their transfer fidelity is too low to assure
reliable connections. We propose a method of optimizing the fidelity by minimal
usage of the available resources, consisting of applying a suitable sequence of
two-qubit gates at the end of the chain. Our scheme allows also the preparation
of states in the first excitation sector as well as cooling.
| [
{
"version": "v1",
"created": "Tue, 3 Oct 2006 16:31:33 GMT"
},
{
"version": "v2",
"created": "Tue, 3 Apr 2007 07:57:17 GMT"
},
{
"version": "v3",
"created": "Wed, 23 May 2007 17:10:39 GMT"
}
]
| 2007-06-22T00:00:00 | [
[
"Burgarth",
"D.",
""
],
[
"Giovannetti",
"V.",
""
],
[
"Bose",
"S.",
""
]
]
|
quant-ph/0610019 | Gilles Nogues | Thomas Nirrengarten (LKB - Lhomond), Angie Qarry (LKB - Lhomond),
C\'edric Roux (LKB - Lhomond), Andreas Emmert (LKB - Lhomond), Gilles Nogues
(LKB - Lhomond), Michel Brune (LKB - Lhomond), Jean-Michel Raimond (LKB -
Lhomond), Serge Haroche (LKB - Lhomond, CDF) | Realization of a superconducting atom chip | Submitted to Phys. Rev. Lett | Physical review letters 97 (17/11/2006) 200405 | 10.1103/PhysRevLett.97.200405 | null | quant-ph | null | We have trapped rubidium atoms in the magnetic field produced by a
superconducting atom chip operated at liquid Helium temperatures. Up to
$8.2\cdot 10^5$ atoms are held in a Ioffe-Pritchard trap at a distance of 440
$\mu$m from the chip surface, with a temperature of 40 $\mu$K. The trap
lifetime reaches 115 s at low atomic densities. These results open the way to
the exploration of atom--surface interactions and coherent atomic transport in
a superconducting environment, whose properties are radically different from
normal metals at room temperature.
| [
{
"version": "v1",
"created": "Tue, 3 Oct 2006 20:17:24 GMT"
},
{
"version": "v2",
"created": "Mon, 9 Oct 2006 12:08:45 GMT"
}
]
| 2016-08-16T00:00:00 | [
[
"Nirrengarten",
"Thomas",
"",
"LKB - Lhomond"
],
[
"Qarry",
"Angie",
"",
"LKB - Lhomond"
],
[
"Roux",
"Cédric",
"",
"LKB - Lhomond"
],
[
"Emmert",
"Andreas",
"",
"LKB - Lhomond"
],
[
"Nogues",
"Gilles",
"",
"LKB - Lhomond"
],
[
"Brune",
"Michel",
"",
"LKB - Lhomond"
],
[
"Raimond",
"Jean-Michel",
"",
"LKB -\n Lhomond"
],
[
"Haroche",
"Serge",
"",
"LKB - Lhomond, CDF"
]
]
|
quant-ph/0610020 | Viswanath Ramakrishna | M. C. Tseng, Hong Zhou and V. Ramakrishna | Parametrizations of Positive Matrices With Applications | Submitted for publication to the refereed book ``Mathematics of
Quantum Computation and Technology", and is dedicated to the memory of
Professor Tiberiu Constantinescu | null | null | null | quant-ph | null | This paper reviews some characterizations of positive matrices and discusses
which lead to useful parametrizations. It is argued that one of them, which we
dub the Schur-Constantinescu parametrization is particularly useful. Two new
applications of it are given. One shows all block-Toeplitz states are PPT. The
other application is to relaxation rates.
| [
{
"version": "v1",
"created": "Tue, 3 Oct 2006 21:16:26 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Tseng",
"M. C.",
""
],
[
"Zhou",
"Hong",
""
],
[
"Ramakrishna",
"V.",
""
]
]
|
quant-ph/0610021 | Viswanath Ramakrishna | M. C. Tseng and V. Ramakrishna | Dilation Theoretic Parametrizations of Positive Matrices with
Applications to Quantum Information | Submitted to the Tiberiu Constantinescu Memorial Volume | null | null | null | quant-ph | null | This paper, dedicated to the memory of late Professor Tiberiu Constantinescu,
discusses two parametrizations of positive matrices. The first, called the
Schur-Constantinescu parametrization, is used to construct several examples of
separable states (e.g., Hankel states). The second, called the Jacobi
parametrization, is used to present an alternative to the Bloch sphere
representation of qubits.
| [
{
"version": "v1",
"created": "Tue, 3 Oct 2006 21:28:54 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Tseng",
"M. C.",
""
],
[
"Ramakrishna",
"V.",
""
]
]
|
quant-ph/0610022 | Gour Pati | G.S. Pati, M. Salit, K. Salit, and M.S. Shahriar | Demonstration of a Tunable-Bandwidth White Light Interferometer using
Anomalous Dispersion in Atomic Vapor | 11 Pages, 2 figures | null | 10.1103/PhysRevLett.99.133601 | null | quant-ph | null | Recently, the design of a white-light-cavity has been proposed using negative
dispersion in an intra-cavity medium to make the cavity resonate over a large
range of frequencies and still maintain a high cavity build-up. This paper
presents the demonstration of this effect in a free-space cavity. The negative
dispersion of the intra-cavity medium is caused by bi-frequency Raman gain in
an atomic vapor cell. A significantly broad cavity response over a bandwidth
greater than 20 MHz has been observed. The experimental results agree well with
the theoretical model, taking into account effects of residual absorption. A
key application of this device would be in enhancing the sensitivity-bandwidth
product of the next generation gravitational wave detectors that make use of
the so-called signal-recycling mirror.
| [
{
"version": "v1",
"created": "Wed, 4 Oct 2006 06:23:46 GMT"
},
{
"version": "v2",
"created": "Sun, 8 Oct 2006 19:07:56 GMT"
},
{
"version": "v3",
"created": "Tue, 24 Oct 2006 22:53:54 GMT"
},
{
"version": "v4",
"created": "Mon, 18 Dec 2006 23:39:42 GMT"
},
{
"version": "v5",
"created": "Wed, 21 Feb 2007 18:29:52 GMT"
},
{
"version": "v6",
"created": "Mon, 11 Jun 2007 22:54:42 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Pati",
"G. S.",
""
],
[
"Salit",
"M.",
""
],
[
"Salit",
"K.",
""
],
[
"Shahriar",
"M. S.",
""
]
]
|
quant-ph/0610023 | Gour Pati | G.S. Pati, M. Salit, K. Salit, and M.S. Shahriar | Demonstration of Tunable Displacement-Measurement-Sensitivity using
Variable Group Index in a Ring Resonator | 14 Pages, 4 figures | null | null | null | quant-ph | null | We show that an intra-cavity medium with normal dispersion reduces the
sensitivity of the cavity resonance frequency to a change in its length by a
factor inversely proportional to the group index. Since the group index in an
atomic medium can be very large, this effect can help in constructing highly
frequency-stable cavities for various potential applications without taking
additional measures for mechanical stability. The results also establish
indirectly the opposite effect of enhanced sensitivity that can be realized for
a negative dispersion corresponding to a group index close to a null value.
This enhancement in turn can be employed to increase significantly the
sensitivity of a ring laser gyroscope.
| [
{
"version": "v1",
"created": "Wed, 4 Oct 2006 06:29:11 GMT"
},
{
"version": "v2",
"created": "Tue, 24 Oct 2006 22:49:09 GMT"
},
{
"version": "v3",
"created": "Mon, 18 Dec 2006 23:36:38 GMT"
},
{
"version": "v4",
"created": "Wed, 21 Feb 2007 18:34:28 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Pati",
"G. S.",
""
],
[
"Salit",
"M.",
""
],
[
"Salit",
"K.",
""
],
[
"Shahriar",
"M. S.",
""
]
]
|
quant-ph/0610024 | Hector Bombin | H. Bombin, M.A. Martin-Delgado | Topological Computation without Braiding | revtex4, 4 pages, 4 figures | Phys.Rev.Lett.98:160502,2007 | 10.1103/PhysRevLett.98.160502 | null | quant-ph cond-mat.str-el hep-th | null | We show that universal quantum computation can be performed within the ground
state of a topologically ordered quantum system, which is a naturally protected
quantum memory. In particular, we show how this can be achieved using brane-net
condensates in 3-colexes. The universal set of gates is implemented without
selective addressing of physical qubits and, being fully topologically
protected, it does not rely on quasiparticle excitations or their braiding.
| [
{
"version": "v1",
"created": "Wed, 4 Oct 2006 09:19:24 GMT"
},
{
"version": "v2",
"created": "Thu, 29 Mar 2007 14:36:57 GMT"
}
]
| 2008-11-26T00:00:00 | [
[
"Bombin",
"H.",
""
],
[
"Martin-Delgado",
"M. A.",
""
]
]
|
quant-ph/0610025 | Sandu Popescu | Sandu Popescu | KLM quantum computation as a measurement based computation | 4 pages 3 figures | null | 10.1103/PhysRevLett.99.250501 | null | quant-ph | null | We show that the Knill Laflamme Milburn method of quantum computation with
linear optics gates can be interpreted as a one-way, measurement based quantum
computation of the type introduced by Briegel and Rausendorf. We also show that
the permanent state of n n-dimensional systems is a universal state for quantum
computation.
| [
{
"version": "v1",
"created": "Wed, 4 Oct 2006 13:50:02 GMT"
}
]
| 2013-05-29T00:00:00 | [
[
"Popescu",
"Sandu",
""
]
]
|
quant-ph/0610026 | Paulo Maia Neto | Robson B. Rodrigues, Paulo A. Maia Neto, A. Lambrecht and S. Reynaud | Vacuum induced torque between corrugated metallic plates | 7 pages, 4 figures, to appear in Europhysics Letters. Technical
problem with eps file for figure 4 was fixed | Europhys.Lett.76:822-828,2006 | 10.1209/epl/i2006-10340-1 | null | quant-ph hep-th | null | We study the torque arising between two corrugated metallic plates due to the
interaction with electromagnetic vacuum. This Casimir torque can be measured
with torsion pendulum techniques for separation distances as large as 1$\mu$m.
It allows one to probe the nontrivial geometry dependence of the Casimir energy
in a configuration which can be evaluated theoretically with accuracy. In the
optimal experimental configuration, the commonly used proximity force
approximation turns out to overestimate the torque by a factor 2 or larger.
| [
{
"version": "v1",
"created": "Wed, 4 Oct 2006 17:28:47 GMT"
},
{
"version": "v2",
"created": "Wed, 4 Oct 2006 20:32:24 GMT"
},
{
"version": "v3",
"created": "Tue, 10 Oct 2006 19:37:26 GMT"
}
]
| 2010-12-17T00:00:00 | [
[
"Rodrigues",
"Robson B.",
""
],
[
"Neto",
"Paulo A. Maia",
""
],
[
"Lambrecht",
"A.",
""
],
[
"Reynaud",
"S.",
""
]
]
|
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