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|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
quant-ph/0608115 | Ulf Leonhardt | U. Leonhardt and T. G. Philbin | Quantum levitation by left-handed metamaterials | null | null | 10.1088/1367-2630/9/8/254 | null | quant-ph cond-mat.mtrl-sci physics.optics | null | Left-handed metamaterials make perfect lenses that image classical
electromagnetic fields with significantly higher resolution than the
diffraction limit. Here we consider the quantum physics of such devices. We
show that the Casimir force of two conducting plates may turn from attraction
to repulsion if a perfect lens is sandwiched between them. For optical
left-handed metamaterials this repulsive force of the quantum vacuum may
levitate ultra-thin mirrors.
| [
{
"version": "v1",
"created": "Mon, 14 Aug 2006 14:26:03 GMT"
},
{
"version": "v2",
"created": "Fri, 15 Dec 2006 09:55:19 GMT"
},
{
"version": "v3",
"created": "Wed, 20 Dec 2006 09:45:38 GMT"
},
{
"version": "v4",
"created": "Wed, 25 Apr 2007 16:01:16 GMT"
},
{
"version": "v5",
"created": "Thu, 19 Jul 2007 09:59:37 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Leonhardt",
"U.",
""
],
[
"Philbin",
"T. G.",
""
]
]
|
quant-ph/0608116 | Iwo Bialynicki-Birula | Iwo Bialynicki-Birula | Formulation of the uncertainty relations in terms of the Renyi entropies | null | Phys. Rev. A 74, 052101 (2006) | 10.1103/PhysRevA.74.052101 | null | quant-ph | null | Quantum mechanical uncertainty relations for position and momentum are
expressed in the form of inequalities involving the Renyi entropies. The proof
of these inequalities requires the use of the exact expression for the
(p,q)-norm of the Fourier transformation derived by Babenko and Beckner.
Analogous uncertainty relations are derived for angle and angular momentum and
also for a pair of complementary observables in N-level systems. All these
uncertainty relations become more attractive when expressed in terms of the
symmetrized Renyi entropies.
| [
{
"version": "v1",
"created": "Mon, 14 Aug 2006 14:41:10 GMT"
},
{
"version": "v2",
"created": "Sat, 11 Nov 2006 12:58:49 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Bialynicki-Birula",
"Iwo",
""
]
]
|
quant-ph/0608117 | Arkadiusz Jadczyk | Arkadiusz Jadczyk | Quantum fractals on n-spheres. Clifford Algebra approach | Latex. 49 pages. 9 figures. Corrected two misprints in Sec. 3. R(2,C)
at the beginning has been replaced by C(V,Q), and `isomorphism' just before
Theorem 1 has been replaced by `homomorphism' | Adv.Appl.CliffordAlgebras17:201-240,2007 | 10.1007/s00006-006-0020-9 | null | quant-ph nlin.CD | null | Using the Clifford algebra formalism we extend the quantum jumps algorithm of
the Event Enhanced Quantum Theory (EEQT) to convex state figures other than
those stemming from convex hulls of complex projective spaces that form the
basis for the standard quantum theory. We study quantum jumps on n-dimensional
spheres, jumps that are induced by symmetric configurations of non-commuting
state monitoring detectors. The detectors cause quantum jumps via geometrically
induced conformal maps (Mobius transformations) and realize iterated function
systems (IFS) with fractal attractors located on n-dimensional spheres. We also
extend the formalism to mixed states, represented by "density matrices". As a
numerical illustration we study quantum fractals on the circle, two--sphere
(octahedron), and on three-dimensional sphere (hypercube-tesseract, 24 cell,
600 cell,and 120 cell). The invariant measure on the attractor is approximated
by the powers of the Markov operator. In the appendices we calculate the
Radon-Nikodym derivative of the SO(n+1) invariant measure on S^n under
SO(1,n+1) transformations and discuss the Hamilton's "icossian calculus" as
well as its application to quaternionic realization of the binary icosahedral
group that is at the basis of the 600 cell and its dual, the 120 cell. As a
by-product of this work we obtain several Clifford algebraic results, such as a
characterization of positive elements in a Clifford algebra Cl(n+1) as
generalized Lorentz boosts, and their action as Moebius transformation on
n-sphere, and a decomposition of any element of Spin^+(1,n+1) into a boost and
a rotation, including the explicit formula for the pullback of the O(n+1)
invariant Riemannian metric with respect to the associated Mobius
transformation.
| [
{
"version": "v1",
"created": "Mon, 14 Aug 2006 18:43:27 GMT"
},
{
"version": "v2",
"created": "Mon, 4 Sep 2006 17:02:04 GMT"
},
{
"version": "v3",
"created": "Fri, 6 Oct 2006 19:57:36 GMT"
},
{
"version": "v4",
"created": "Sat, 25 Nov 2006 10:51:26 GMT"
},
{
"version": "v5",
"created": "Fri, 25 May 2007 17:54:33 GMT"
}
]
| 2008-11-26T00:00:00 | [
[
"Jadczyk",
"Arkadiusz",
""
]
]
|
quant-ph/0608118 | Stefan Yoshi Buhmann | Stefan Yoshi Buhmann and Dirk-Gunnar Welsch | Dispersion forces in macroscopic quantum electrodynamics | 112 pages, 7 figures, 4 tables, extended version | Progress in Quantum Electronics 31 (2) 51 (2007) | 10.1016/j.pquantelec.2007.03.001 | null | quant-ph | null | The description of dispersion forces within the framework of macroscopic
quantum electrodynamics in linear, dispersing, and absorbing media combines the
benefits of approaches based on normal-mode techniques of standard quantum
electrodynamics and methods based on linear response theory in a natural way.
It renders generally valid expressions for both the forces between bodies and
the forces on atoms in the presence of bodies, while showing very clearly the
intimate relation between the different types of dispersion forces. By
considering examples, the influence of various factors like form, size,
electric and magnetic properties, or intervening media on the forces is
addressed. Since the approach based on macroscopic quantum electrodynamics does
not only apply to equilibrium systems, it can be used to investigate dynamical
effects such as the temporal evolution of forces on arbitrarily excited atoms.
| [
{
"version": "v1",
"created": "Mon, 14 Aug 2006 20:38:30 GMT"
},
{
"version": "v2",
"created": "Tue, 12 Jun 2007 14:42:09 GMT"
}
]
| 2010-01-04T00:00:00 | [
[
"Buhmann",
"Stefan Yoshi",
""
],
[
"Welsch",
"Dirk-Gunnar",
""
]
]
|
quant-ph/0608119 | Parsa Bonderson | Parsa Bonderson, Kirill Shtengel, J. K. Slingerland | Decoherence of Anyonic Charge in Interferometry Measurements | 5 pages, 1 figure; v2: reference added, example added, clarifying
changes made to conform to the version published in PRL | Phys. Rev. Lett. 98, 070401 (2007) | 10.1103/PhysRevLett.98.070401 | NSF-KITP-06-51 | quant-ph cond-mat.mes-hall hep-th | null | We examine interferometric measurements of the topological charge of
(non-Abelian) anyons. The target's topological charge is measured from its
effect on the interference of probe particles sent through the interferometer.
We find that superpositions of distinct anyonic charges a and a' in the target
decohere (exponentially in the number of probes particles used) when the probes
have nontrivial monodromy with the charges that may be fused with a to give a'.
| [
{
"version": "v1",
"created": "Mon, 14 Aug 2006 23:38:28 GMT"
},
{
"version": "v2",
"created": "Tue, 31 Jul 2007 01:36:12 GMT"
}
]
| 2009-09-21T00:00:00 | [
[
"Bonderson",
"Parsa",
""
],
[
"Shtengel",
"Kirill",
""
],
[
"Slingerland",
"J. K.",
""
]
]
|
quant-ph/0608120 | Terry Rudolph | Terry Rudolph | Ontological Models for Quantum Mechanics and the Kochen-Specker theorem | These theories are not quantum mechanics. But they should be | null | null | null | quant-ph | null | Certain concrete "ontological models" for quantum mechanics (models in which
measurement outcomes are deterministic and quantum states are equivalent to
classical probability distributions over some space of `hidden variables') are
examined. The models are generalizations of Kochen and Specker's such model for
a single 2-dimensional system - in particular a model for a three dimensional
quantum system is considered in detail. Unfortunately, it appears the models do
not quite reproduce the quantum mechanical statistics. They do, however, come
close to doing so, and in as much as they simply involve probability
distributions over the complex projective space they do reproduce pretty much
everything else in quantum mechanics.
The Kochen-Specker theorem is examined in the light of these models, and the
rather mild nature of the manifested contextuality is discussed.
| [
{
"version": "v1",
"created": "Tue, 15 Aug 2006 04:11:21 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Rudolph",
"Terry",
""
]
]
|
quant-ph/0608121 | Andrew Fisher | H.-C. Lin and A.J. Fisher | Entanglement in general two-mode continuous-variable states: local
approach and mapping to a two-qubit system | 4 pages, RevTeX 4, one figure. Further modifications in response to
journal referees, correction to expression for negativity | null | 10.1103/PhysRevA.76.042320 | null | quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a new approach to the analysis of entanglement in smooth bipartite
continuous-variable states. One or both parties perform projective filterings
via preliminary measurements to determine whether the system is located in some
region of space; we study the entanglement remaining after filtering. For small
regions, a two-mode system can be approximated by a pair of qubits and its
entanglement fully characterized, even for mixed states. Our approach may be
extended to any smooth bipartite pure state or two-mode mixed state, leading to
natural definitions of concurrence and negativity densities. For Gaussian
states both these quantities are constant throughout configuration space.
| [
{
"version": "v1",
"created": "Tue, 15 Aug 2006 15:40:57 GMT"
},
{
"version": "v2",
"created": "Tue, 23 Jan 2007 11:52:11 GMT"
},
{
"version": "v3",
"created": "Thu, 7 Jun 2007 13:23:14 GMT"
},
{
"version": "v4",
"created": "Wed, 4 Mar 2009 15:11:49 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Lin",
"H. -C.",
""
],
[
"Fisher",
"A. J.",
""
]
]
|
quant-ph/0608122 | Stephen A. Fulling | S. A. Fulling, J. H. Wilson | Repulsive Casimir Pistons | 4 pages, 2 figures; RevTeX. Minor additions and corrections | Superseded by Phys. Rev. A 76 (2007) 012118 (quant-ph/0703248) | 10.1103/PhysRevA.76.012118 | null | quant-ph hep-th | null | Casimir pistons are models in which finite Casimir forces can be calculated
without any suspect renormalizations. It has been suggested that such forces
are always attractive. We present three scenarios in which that is not true.
Two of these depend on mixing two types of boundary conditions. The other,
however, is a simple type of quantum graph in which the sign of the force
depends upon the number of edges.
| [
{
"version": "v1",
"created": "Tue, 15 Aug 2006 17:10:55 GMT"
},
{
"version": "v2",
"created": "Sun, 28 Jan 2007 02:07:58 GMT"
}
]
| 2013-05-29T00:00:00 | [
[
"Fulling",
"S. A.",
""
],
[
"Wilson",
"J. H.",
""
]
]
|
quant-ph/0608123 | Ralf Schutzhold | Markus Tiersch and Ralf Sch\"utzhold | Non-Markovian decoherence in the adiabatic quantum search algorithm | null | Phys. Rev. A 75, 062313 (2007) | 10.1103/PhysRevA.75.062313 | null | quant-ph | null | We consider an adiabatic quantum algorithm (Grover's search routine) weakly
coupled to a rather general environment, i.e., without using the Markov
approximation. Markovian errors generally require high-energy excitations (of
the reservoir) and tend to destroy the scalability of the adiabatic quantum
algorithm. We find that, under appropriate conditions (such as low
temperatures), the low-energy (i.e., non-Markovian) modes of the bath are most
important. Hence the scalability of the adiabatic quantum algorithm depends on
the infra-red behavior of the environment: a reasonably small coupling to the
three-dimensional electromagnetic field does not destroy the scaling behavior,
whereas phonons or localized degrees of freedom can be problematic. PACS:
03.67.Pp, 03.67.Lx, 03.67.-a, 03.65.Yz.
| [
{
"version": "v1",
"created": "Tue, 15 Aug 2006 17:41:41 GMT"
}
]
| 2011-11-09T00:00:00 | [
[
"Tiersch",
"Markus",
""
],
[
"Schützhold",
"Ralf",
""
]
]
|
quant-ph/0608124 | Dragomir Z. Djokovic | Dragomir Z. Djokovic | Dimensions of generic local orbits of multipartite quantum systems | 5 pages. The spelling of author's name corrected | null | null | null | quant-ph | null | We consider the action of the group of local unitary transformations, U(m) x
U(n), on the set of (mixed) states W of the bipartite m x n quantum system. We
prove that the generic U(m) x U(n)--orbits in W have dimension m^2+n^2-2. This
problem was mentioned (and left open) by Kus and Zyczkowski in their paper
Geometry of entangled states. The proof can be extended to the case of
arbitrary finite-dimensional multipartite quantum systems.
| [
{
"version": "v1",
"created": "Tue, 15 Aug 2006 19:51:18 GMT"
},
{
"version": "v2",
"created": "Mon, 1 Jan 2007 13:05:47 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Djokovic",
"Dragomir Z.",
""
]
]
|
quant-ph/0608125 | Andr\'es Fernando Reyes Lega | N. A. Papadopoulos, M. Paschke, A. F. Reyes-Lega, F. Scheck | The spin-statistics relation in nonrelativistic quantum mechanics and
projective modules | 16 pages | Annales Mathematiques Blaise Pascal 11, 205-220 (2004) | null | MZ-TH/04-24 | quant-ph | null | In this work we consider non-relativistic quantum mechanics, obtained from a
classical configuration space Q of indistinguishable particles. Following an
approach proposed by one of the authors, wave functions are regarded as
elements of suitable projective modules over C(Q). We take furthermore into
account the G-Theory point of view, where the role of group action is
particularly emphasized. As an example illustrating the method, the case of two
particles is worked out in detail. Previous works aiming at a proof of a
spin-statistics theorem for non-relativistic quantum mechanics are
re-considered from the point of view of our approach, enabling us to clarify
several points.
| [
{
"version": "v1",
"created": "Tue, 15 Aug 2006 21:26:47 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Papadopoulos",
"N. A.",
""
],
[
"Paschke",
"M.",
""
],
[
"Reyes-Lega",
"A. F.",
""
],
[
"Scheck",
"F.",
""
]
]
|
quant-ph/0608126 | Andrew A. Semenov | A.A. Semenov, D.Yu. Vasylyev, W. Vogel, M. Khanbekyan, and D.-G.
Welsch | Characterization of unwanted noise in realistic cavities | Contribution to XI International Conference on Quantum Optics, Minsk,
Belarus, 26-31 May, 2006 | Optics and Spectroscopy 103, 245-251 (2007) | 10.1134/S0030400X07080139 | null | quant-ph physics.optics | null | The problem of the description of absorption and scattering losses in high-Q
cavities is studied. The considerations are based on quantum noise theories,
hence the unwanted noise associated with scattering and absorption is taken
into account by introduction of additional damping and noise terms in the
quantum Langevin equations and input--output relations. Completeness conditions
for the description of the cavity models obtained in this way are studied and
corresponding replacement schemes are discussed.
| [
{
"version": "v1",
"created": "Wed, 16 Aug 2006 12:58:05 GMT"
}
]
| 2007-08-02T00:00:00 | [
[
"Semenov",
"A. A.",
""
],
[
"Vasylyev",
"D. Yu.",
""
],
[
"Vogel",
"W.",
""
],
[
"Khanbekyan",
"M.",
""
],
[
"Welsch",
"D. -G.",
""
]
]
|
quant-ph/0608127 | Xiangyao Wu | Xiang-Yao Wu, Xiao-Jing Liu, Li Wang, Yi-Qing Guo and Xi-Hui Fan | Classical and quantum theory for Superluminal particle | 12 pages | null | null | null | quant-ph | null | As we all know, when the relative velocity of two inertial reference frames
$\sum$ and $\sum^{'}$ is less than the speed of light, the relations of
$x_{\mu}$ with $x_{\mu}^{'}$, a particle mass $m$ with its velocity $\upsilon$,
and a particle mass with its energy are all given by Einstein's special
relativity. In this paper, we will give new relation of $x_{\mu}$ and
$x_{\mu}^{'}$ when the relative velocity of $\sum$ and $\sum^{'}$ frame is
larger than the speed of light, and also we give the relation of a particle
mass $m$ with its velocity $\upsilon$, and a particle mass $m$ with its energy
$E$ when the particle velocity $v$ is larger than the speed of light.
| [
{
"version": "v1",
"created": "Wed, 16 Aug 2006 06:33:26 GMT"
},
{
"version": "v2",
"created": "Wed, 7 Feb 2007 12:21:16 GMT"
},
{
"version": "v3",
"created": "Wed, 16 May 2007 08:30:10 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Wu",
"Xiang-Yao",
""
],
[
"Liu",
"Xiao-Jing",
""
],
[
"Wang",
"Li",
""
],
[
"Guo",
"Yi-Qing",
""
],
[
"Fan",
"Xi-Hui",
""
]
]
|
quant-ph/0608128 | Yeong-Cherng Liang | Yeong-Cherng Liang, Andrew C. Doherty | Bounds on Quantum Correlations in Bell Inequality Experiments | 13 pages, 1 table, 2 figures. Updated version as published in PRA | Physical Review A, vol. 75, art. 042103 (2007) | 10.1103/PhysRevA.75.042103 | null | quant-ph | null | Bell inequality violation is one of the most widely known manifestations of
entanglement in quantum mechanics; indicating that experiments on physically
separated quantum mechanical systems cannot be given a local realistic
description. However, despite the importance of Bell inequalities, it is not
known in general how to determine whether a given entangled state will violate
a Bell inequality. This is because one can choose to make many different
measurements on a quantum system to test any given Bell inequality and the
optimization over measurements is a high-dimensional variational problem. In
order to better understand this problem we present algorithms that provide, for
a given quantum state, both a lower bound and an upper bound on the maximal
expectation value of a Bell operator. Both bounds apply techniques from convex
optimization and the methodology for creating upper bounds allows them to be
systematically improved. In many cases these bounds determine measurements that
would demonstrate violation of the Bell inequality or provide a bound that
rules out the possibility of a violation. Examples are given to illustrate how
these algorithms can be used to conclude definitively if some quantum states
violate a given Bell inequality.
| [
{
"version": "v1",
"created": "Wed, 16 Aug 2006 10:57:39 GMT"
},
{
"version": "v2",
"created": "Tue, 10 Apr 2007 06:55:25 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Liang",
"Yeong-Cherng",
""
],
[
"Doherty",
"Andrew C.",
""
]
]
|
quant-ph/0608129 | Farhan Saif | Farhan Saif and Pierre Meystre | Coherent Acceleration of Material Wavepackets | 6 pages, 3 figures, NASA "Quantum-to-Cosmos" conference proceedings
to be published in IJMPD | null | 10.1142/S021827180701167X | null | quant-ph | null | We study the quantum dynamics of a material wavepacket bouncing off a
modulated atomic mirror in the presence of a gravitational field. We find the
occurrence of coherent accelerated dynamics for atoms. The acceleration takes
place for certain initial phase space data and within specific windows of
modulation strengths. The realization of the proposed acceleration scheme is
within the range of present day experimental possibilities.
| [
{
"version": "v1",
"created": "Wed, 16 Aug 2006 18:24:55 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Saif",
"Farhan",
""
],
[
"Meystre",
"Pierre",
""
]
]
|
quant-ph/0608130 | Tomasz Sowinski | Tomasz Sowinski | Wave functions of linear systems | null | Acta Phys. Polon. B 38, 2173 (2007) | null | null | quant-ph | null | Complete analysis of quantum wave functions of linear systems in an arbitrary
number of dimensions is given. It is shown how one can construct a complete set
of stationary quantum states of an arbitrary linear system from purely
classical arguments. This construction is possible because for linear systems
classical dynamics carries the whole information about quantum dynamics.
| [
{
"version": "v1",
"created": "Wed, 16 Aug 2006 19:41:08 GMT"
},
{
"version": "v2",
"created": "Tue, 5 Jun 2007 19:41:07 GMT"
}
]
| 2007-06-13T00:00:00 | [
[
"Sowinski",
"Tomasz",
""
]
]
|
quant-ph/0608131 | Rubens Ramos Viana | Paulo Benicio Melo de Sousa, Rubens Viana Ramos and Jose Tarcisio
Costa filho | New models of quantum games | 10 pages and 5 figures | null | null | null | quant-ph | null | In this work we propose and develop modified quantum games (zero and non-zero
sum) in which payoffs and strategies are entangled. For the games studied, Nash
and Pareto equilibriums are always obtained indicating that there are some
interesting cases where quantum games can be applied.
| [
{
"version": "v1",
"created": "Thu, 17 Aug 2006 15:28:56 GMT"
},
{
"version": "v2",
"created": "Fri, 6 Oct 2006 17:02:22 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"de Sousa",
"Paulo Benicio Melo",
""
],
[
"Ramos",
"Rubens Viana",
""
],
[
"filho",
"Jose Tarcisio Costa",
""
]
]
|
quant-ph/0608132 | Dan Shepherd | Dan Shepherd | Computation with Unitaries and One Pure Qubit | 16 pages, no figures, submitted to QIC. This version has an improved
section on oracles, adds a note on entanglement, includes minor corrections | null | null | null | quant-ph | null | We define a semantic complexity class based on the model of quantum computing
with just one pure qubit (as introduced by Knill and Laflamme) and discuss its
computational power in terms of the problem of estimating the trace of a large
unitary matrix. We show that this problem is complete for the complexity class,
and derive some further fundamental features of the class. We conclude with a
discussion of some associated open conjectures and new oracle separations
between classes.
| [
{
"version": "v1",
"created": "Thu, 17 Aug 2006 00:37:10 GMT"
},
{
"version": "v2",
"created": "Wed, 29 Nov 2006 14:34:53 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Shepherd",
"Dan",
""
]
]
|
quant-ph/0608133 | Klemens Hammerer | K. Hammerer, E.S. Polzik, J.I. Cirac | High fidelity teleportation between light and atoms | 5 pages, 3 figures | PRA 74, 064301 (2007) | 10.1103/PhysRevA.74.064301 | null | quant-ph | null | We show how high fidelity quantum teleportation of light to atoms can be
achieved in the same setup as was used in the recent experiment [J. Sherson
et.al., quant-ph/0605095, accepted by Nature], where such an inter-species
quantum state transfer was demonstrated for the first time. Our improved
protocol takes advantage of the rich multimode entangled structure of the state
of atoms and scattered light and requires simple post-processing of homodyne
detection signals and squeezed light in order to achieve fidelities up to 90%
(85%) for teleportation of coherent (qubit) states under realistic experimental
conditions. The remaining limitation is due to atomic decoherence and light
losses.
| [
{
"version": "v1",
"created": "Thu, 17 Aug 2006 13:44:49 GMT"
},
{
"version": "v2",
"created": "Wed, 13 Dec 2006 12:50:00 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Hammerer",
"K.",
""
],
[
"Polzik",
"E. S.",
""
],
[
"Cirac",
"J. I.",
""
]
]
|
quant-ph/0608134 | Yasushi Kondo Dr. | Yasushi Kondo, Mikio Nakahara, Shogo Tanimura, Sachiko Kitajima,
Chikako Uchiyama and Fumiaki Shibata | Generation and Suppression of Decoherence in Artificial Environment for
Qubit System | 25 pages, 7 figures; added references | null | 10.1143/JPSJ.76.074002 | null | quant-ph | null | It is known that a quantum system with finite degrees of freedom can simulate
a composite of a system and an environment if the state of the hypothetical
environment is randomized by external manipulation. We show theoretically that
any phase decoherence phenomena of a single qubit can be simulated with a
two-qubit system and demonstrate experimentally two examples: one is phase
decoherence of a single qubit in a transmission line, and the other is that in
a quantum memory. We perform NMR experiments employing a two-spin molecule and
clearly measure decoherence for both cases. We also prove experimentally that
the bang-bang control efficiently suppresses decoherence.
| [
{
"version": "v1",
"created": "Thu, 17 Aug 2006 06:23:19 GMT"
},
{
"version": "v2",
"created": "Wed, 6 Sep 2006 01:17:09 GMT"
},
{
"version": "v3",
"created": "Sat, 10 Feb 2007 06:43:55 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Kondo",
"Yasushi",
""
],
[
"Nakahara",
"Mikio",
""
],
[
"Tanimura",
"Shogo",
""
],
[
"Kitajima",
"Sachiko",
""
],
[
"Uchiyama",
"Chikako",
""
],
[
"Shibata",
"Fumiaki",
""
]
]
|
quant-ph/0608135 | Lan Zhou | Lan Zhou, Jing Lu, Tao Shi, C. P. Sun | Decoherence problem in quantum state transfer via an engineered spin
chain | 6 pages, 3 figures | null | null | null | quant-ph | null | A perfect quantum state transfer(QST) has been shown in an engineered spin
chain with "always-on interaction". Here, we consider a more realistic problem
for such a protocol, the quantum decoherence induced by a spatially distributed
environment, which is universally modeled as a bath of harmonic oscillators. By
making use of the irreducible tensor method in angular momentum theory, we
investigate the effect of decoherence on the efficiency of QST for both cases
at zero and finite temperatures. We not only show the generic exponential decay
of QST efficiency as the number of sites increase, but also find some
counterintuitive effect, the QST can be enhanced as temperature increase.
| [
{
"version": "v1",
"created": "Thu, 17 Aug 2006 09:37:07 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Zhou",
"Lan",
""
],
[
"Lu",
"Jing",
""
],
[
"Shi",
"Tao",
""
],
[
"Sun",
"C. P.",
""
]
]
|
quant-ph/0608136 | Alessio Serafini | A. Serafini | Multimode uncertainty relations and separability of continuous variable
states | 4 pages, no figures; shorter version of a longer version (see
quant-ph/0508231), published | Phys. Rev. Lett. 96, 110402 (2006) | 10.1103/PhysRevLett.96.110402 | null | quant-ph | null | A multimode uncertainty relation (generalising the Robertson-Schroedinger
relation) is derived as a necessary constraint on the second moments of n pairs
of canonical operators. In turn, necessary conditions for the separability of
multimode continuous variable states under (m+n)-mode bipartitions are derived
from the uncertainty relation. These conditions are proven to be necessary and
sufficient for (1+n)-mode Gaussian states and for (m+n)-mode bisymmetric
Gaussian states.
| [
{
"version": "v1",
"created": "Thu, 17 Aug 2006 17:48:36 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Serafini",
"A.",
""
]
]
|
quant-ph/0608137 | Dominic William Berry | Dominic W. Berry | Implementation of multipartite unitary operations with limited resources | 7 pages, 4 figures, comments welcome | Phys. Rev. A 75, 032349 (2007) | 10.1103/PhysRevA.75.032349 | null | quant-ph | null | A general method for implementing weakly entangling multipartite unitary
operations using a small amount of entanglement and classical communication is
presented. For the simple Hamiltonian \sigma_z\otimes\sigma_z this method
requires less entanglement than previously known methods. In addition,
compression of multiple operations is applied to reduce the average
communication required.
| [
{
"version": "v1",
"created": "Sun, 20 Aug 2006 07:51:52 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Berry",
"Dominic W.",
""
]
]
|
quant-ph/0608138 | Dmitry Arbatsky | D. A. Arbatsky | The certainty principle (review) | One paper, in Russian and in English, no figures | null | null | null | quant-ph | null | The certainty principle (2005) allowed to conceptualize from the more
fundamental grounds both the Heisenberg uncertainty principle (1927) and the
Mandelshtam-Tamm relation (1945). In this review I give detailed explanation
and discussion of the certainty principle, oriented to all physicists, both
theorists and experimenters.
| [
{
"version": "v1",
"created": "Thu, 17 Aug 2006 22:46:17 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Arbatsky",
"D. A.",
""
]
]
|
quant-ph/0608139 | Daniel Cavalcanti | Daniel Cavalcanti, J. G. Oliveira Jr, J. G. Peixoto de Faria, Marcelo
O. Terra Cunha, and Marcelo Franca Santos | Entanglement versus energy in the entanglement transfer problem | 11 pages, 6 figs. v2: references added, text and figures improved | Phys. Rev. A 74, 042328 (2006) | 10.1103/PhysRevA.74.042328 | null | quant-ph | null | We study the relation between energy and entanglement in an entanglement
transfer problem. We first analyze the general setup of two entangled qubits (a
and b) exchanging this entanglement with two other independent qubits (A and
B). Qubit a (b) interacts with qubit A (B) via a spin exchange-like unitary
evolution. A physical realization of this scenario could be the problem of
two-level atoms transferring entanglement to resonant cavities via independent
Jaynes-Cummings interactions. We study the dynamics of entanglement and energy
for the second pair of qubits (tracing out the originally entangled ones) and
show that these quantities are closely related. For example, the allowed
quantum states occupy a restricted area in a phase diagram entanglement vs.
energy. Moreover the curve which bounds this area is exactly the one followed
if both interactions are equal and the entire four qubit system is isolated. We
also consider the case when the target pair of qubits is subjected to losses
and can spontaneously decay.
| [
{
"version": "v1",
"created": "Fri, 18 Aug 2006 18:53:02 GMT"
},
{
"version": "v2",
"created": "Tue, 29 Aug 2006 18:00:29 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Cavalcanti",
"Daniel",
""
],
[
"Oliveira",
"J. G.",
"Jr"
],
[
"de Faria",
"J. G. Peixoto",
""
],
[
"Cunha",
"Marcelo O. Terra",
""
],
[
"Santos",
"Marcelo Franca",
""
]
]
|
quant-ph/0608140 | David Derbes | Freeman J. Dyson | 1951 Lectures on Advanced Quantum Mechanics Second Edition | 149 page 10pt report class LateX document using many special
formatting packages and including 10 EPS graphics files loaded with the
graphicx package | null | null | null | quant-ph hep-th physics.hist-ph | null | The legendary 1951 Dyson Lectures on Advanced Quantum Mechanics are finally
LaTeXed, with thorough annotations and an index as an added bonus. See the
Typist's Afterward preceding the backmatter for an explanation of this new
version, and for the historical context see the website:
http://hrst.mit.edu/hrs/renormalization/dyson51-intro/ as well as the author's
website at the Princeton Institute for Advanced Study:
http://www.sns.ias.edu/~dyson/
| [
{
"version": "v1",
"created": "Fri, 18 Aug 2006 19:01:11 GMT"
}
]
| 2009-09-29T00:00:00 | [
[
"Dyson",
"Freeman J.",
""
]
]
|
quant-ph/0608141 | Daniel Cavalcanti | Daniel Cavalcanti, L. M. Moreira, Franklin Matinaga, Marcelo O. Terra
Cunha, and Marcelo Franca Santos | Useful entanglement from the Pauli principle | 5 pages, 3 figures. V2: accepted version - text improved, 4 pages, 2
figs | Phys. Rev. B 76, 113304 (2007) | 10.1103/PhysRevB.76.113304 | null | quant-ph cond-mat.str-el | null | We address the question whether identical-particle entanglement is a useful
resource for quantum information processing. We answer this question positively
by reporting a scheme to create entanglement using semiconductor quantum wells.
The Pauli exclusion principle forces quantum correlations between the spins of
two independent fermions in the conduction band. Selective electron-hole
recombination then transfers this entanglement to the polarization of emitted
photons, which can subsequently be used for quantum information tasks.
| [
{
"version": "v1",
"created": "Fri, 18 Aug 2006 18:45:08 GMT"
},
{
"version": "v2",
"created": "Sat, 29 Sep 2007 13:14:38 GMT"
}
]
| 2007-09-29T00:00:00 | [
[
"Cavalcanti",
"Daniel",
""
],
[
"Moreira",
"L. M.",
""
],
[
"Matinaga",
"Franklin",
""
],
[
"Cunha",
"Marcelo O. Terra",
""
],
[
"Santos",
"Marcelo Franca",
""
]
]
|
quant-ph/0608142 | Scott Aaronson | Scott Aaronson | The Learnability of Quantum States | 30 pages; added discussion of adaptive measurements, moved proofs to
appendix, and corrected various minor errors | null | 10.1098/rspa.2007.0113 | null | quant-ph | null | Traditional quantum state tomography requires a number of measurements that
grows exponentially with the number of qubits n. But using ideas from
computational learning theory, we show that "for most practical purposes" one
can learn a state using a number of measurements that grows only linearly with
n. Besides possible implications for experimental physics, our learning theorem
has two applications to quantum computing: first, a new simulation of quantum
one-way communication protocols, and second, the use of trusted classical
advice to verify untrusted quantum advice.
| [
{
"version": "v1",
"created": "Fri, 18 Aug 2006 02:57:52 GMT"
},
{
"version": "v2",
"created": "Sun, 20 Aug 2006 07:44:06 GMT"
},
{
"version": "v3",
"created": "Sun, 4 Mar 2007 14:08:41 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Aaronson",
"Scott",
""
]
]
|
quant-ph/0608143 | Kenichiro Furuta | Kenichiro Furuta, Hirofumi Muratani, Taichi Isogai, Tomoko Yonemura | Analyzing the effectiveness of the quantum repeater | null | null | null | null | quant-ph | null | The communication distance of QKD is limited by exponential attenuation of
photons propagating through optical fibers. However, it has been shown that
introducing a quantum repeater can improve the order of the attenuation and is
useful for extending the communication distance of QKD when the repeater noise
is ignored. In this paper, we analyze the effectiveness of the quantum repeater
when taking the repeater noise into consideration. We analyze the effectiveness
also from the viewpoint of the security and show that QKD is secure even if a
quantum repeater is used.
| [
{
"version": "v1",
"created": "Fri, 18 Aug 2006 10:14:35 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Furuta",
"Kenichiro",
""
],
[
"Muratani",
"Hirofumi",
""
],
[
"Isogai",
"Taichi",
""
],
[
"Yonemura",
"Tomoko",
""
]
]
|
quant-ph/0608144 | Ryo Namiki | Ryo Namiki and Takuya Hirano | Efficient-phase-encoding protocols for continuous-variable quantum key
distribution using coherent states and postselection | RevTeX4, 8 pages, 9 figures | Phys. Rev. A 74, 032302 (2006) | 10.1103/PhysRevA.74.032302 | null | quant-ph | null | We propose efficient-phase-encoding protocols for continuous-variable quantum
key distribution using coherent states and postselection. By these phase
encodings, the probability of basis mismatch is reduced and total efficiency is
increased. We also propose mixed-state protocols by omitting a part of
classical communication steps in the efficient-phase-encoding protocols. The
omission implies a reduction of information to an eavesdropper and possibly
enhances the security of the protocols. We investigate the security of the
protocols against individual beam splitting attack.
| [
{
"version": "v1",
"created": "Fri, 18 Aug 2006 09:17:30 GMT"
}
]
| 2008-09-29T00:00:00 | [
[
"Namiki",
"Ryo",
""
],
[
"Hirano",
"Takuya",
""
]
]
|
quant-ph/0608145 | Erik Hostens | Erik Hostens, Jeroen Dehaene, Bart De Moor | Stabilizer state breeding | RevTeX4, 9 pages, 1 figure | Phys. Rev. A 74, 062318 (2006) | 10.1103/PhysRevA.74.062318 | null | quant-ph | null | We present a breeding protocol that distills pure copies of any stabilizer
state from noisy copies and a pool of predistilled pure copies of the same
state, by means of local Clifford operations, Pauli measurements and classical
communication.
| [
{
"version": "v1",
"created": "Fri, 18 Aug 2006 09:50:46 GMT"
}
]
| 2013-05-29T00:00:00 | [
[
"Hostens",
"Erik",
""
],
[
"Dehaene",
"Jeroen",
""
],
[
"De Moor",
"Bart",
""
]
]
|
quant-ph/0608146 | Sarvagya Upadhyay | Richard Cleve, William Slofstra, Falk Unger, Sarvagya Upadhyay | Strong Parallel Repetition Theorem for Quantum XOR Proof Systems | 17 pages, no figures | null | null | null | quant-ph | null | We consider a class of two-prover interactive proof systems where each prover
returns a single bit to the verifier and the verifier's verdict is a function
of the XOR of the two bits received. We show that, when the provers are allowed
to coordinate their behavior using a shared entangled quantum state, a perfect
parallel repetition theorem holds in the following sense. The prover's optimal
success probability for simultaneously playing a collection of XOR proof
systems is exactly the product of the individual optimal success probabilities.
This property is remarkable in view of the fact that, in the classical case
(where the provers can only utilize classical information), it does not hold.
The theorem is proved by analyzing parities of XOR proof systems using
semidefinite programming techniques, which we then relate to parallel
repetitions of XOR games via Fourier analysis.
| [
{
"version": "v1",
"created": "Fri, 18 Aug 2006 23:01:12 GMT"
},
{
"version": "v2",
"created": "Fri, 11 Apr 2008 16:06:58 GMT"
}
]
| 2008-04-11T00:00:00 | [
[
"Cleve",
"Richard",
""
],
[
"Slofstra",
"William",
""
],
[
"Unger",
"Falk",
""
],
[
"Upadhyay",
"Sarvagya",
""
]
]
|
quant-ph/0608147 | Gustavo Lopez | Gustavo V. Lopez and Lorena Lara | Numerical simulation of a Controlled-Controlled-Not (CCN) quantum gate
in a chain of three interacting nuclear spins system | 9 pages, 5 fugures | null | 10.1088/0953-4075/39/18/019 | null | quant-ph | null | We present the study of a quantum Controlled-Controlled-Not gate, implemented
in a chain of three nuclear spins weakly Ising interacting between all of them,
that is, taking into account first and second neighbor spin interactions. This
implementation is done using a single resonant $\pi$-pulse on the initial state
of the system (digital and superposition). The fidelity parameter is used to
determine the behavior of the CCN quantum gate as a function of the ratio of
the second neighbor interaction coupling constant to the first neighbor
interaction coupling constant ($J'/J$). We found that for $J'/J\ge 0.02$ we can
have a well defined CCN quantum gate.
| [
{
"version": "v1",
"created": "Fri, 18 Aug 2006 23:32:17 GMT"
},
{
"version": "v2",
"created": "Mon, 28 Aug 2006 22:23:59 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Lopez",
"Gustavo V.",
""
],
[
"Lara",
"Lorena",
""
]
]
|
quant-ph/0608148 | Gustavo Lopez | Gustavo V. Lopez and Lorena Lara | Chain of nuclear spins system quantum computer taking into account
second neighbor Ising spins interaction and numerical simulation of Shor
factorization of N=4 | 10 pages, 7 figures | null | null | null | quant-ph | null | For a one-dimensional chain of four nuclear spins (1/2) and taking into
account first and second neighbor interactions among the spin system, we make
the numerical simulation of Shor prime factorization algorithm of the integer
number N=4 to study the influence of the second neighbor interaction on the
performance of this algorithm. It is shown that the optimum Rabi's frequency to
control the non-resonant effects is dominated by the second neighbor
interaction coupling parameter ($J'$), and that a good Shor quantum
factorization is achieved for a ratio of second to first coupling constant of
$J'/J\ge 0.04$.
| [
{
"version": "v1",
"created": "Fri, 18 Aug 2006 23:43:49 GMT"
},
{
"version": "v2",
"created": "Mon, 28 Aug 2006 22:28:04 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Lopez",
"Gustavo V.",
""
],
[
"Lara",
"Lorena",
""
]
]
|
quant-ph/0608149 | Gustavo Lopez | Gustavo Lopez | Quantization of a one-dimensional time-dependent periodic system with
Hamiltonian and constants of motion approaches | 8 pages, non figures | null | null | null | quant-ph | null | For a particle moving in a one-dimensional space an under a periodic external
force, its quantization is study using the Hamiltonian (generalized linear
momentum quantization) and constant of motion (velocity quantization)
approaches. it is shown a great difference on the quantization of both
approaches and the ambiguities arisen by using the quantization on the
constants of motion.
| [
{
"version": "v1",
"created": "Fri, 18 Aug 2006 23:57:05 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Lopez",
"Gustavo",
""
]
]
|
quant-ph/0608150 | Stephen Spratlin Bullock | Stephen S Bullock | Projecting onto Qubit Irreps of Young Diagrams | 7+1 pages, two tables, one figure, one algorithm | null | null | null | quant-ph | null | Let K be the diagonal subgroup of U(2)^{(x)n}. We may view the one-qubit
state-space H_1 as a standard representation of U(2) and the n-qubit state
space H_n=(H_1)^{(x) n} as the n-fold tensor product of standard
representations. Representation theory then decomposes H_n into irreducible
subrepresentations of K parametrized by combinatorial objects known as Young
diagrams. We argue that n-1 classically controlled measurement circuits, each a
Fredkin-gate interferometer, may be used to form a projection operator onto a
random Young diagram irrep within H_n. For H_2, the two irreps happen to be
orthogonal and correspond to the symmetric and wedge product. The latter is
spanned by ket{Psi^-}, and the standard two-qubit swap interferometer requiring
a single Fredkin gate suffices in this case. In the n-qubit case, it is
possible to extract many copies of ket{Psi^-}. Thus applying this process using
nondestructive Fredkin interferometers allows for the creation of entangled
bits (e-bits) using fully mixed states and von Neumann measurements.
| [
{
"version": "v1",
"created": "Sat, 19 Aug 2006 00:22:49 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Bullock",
"Stephen S",
""
]
]
|
quant-ph/0608151 | Shao-Ming Fei | Xiao-Hong Wang, Shao-Ming Fei, Ke Wu | Separability and Entanglement of Identical Bosonic Systems | 4 pages | J. Phys. A 39, Gen. and Math. (2006)L555-L557 | 10.1088/0305-4470/39/36/L01 | null | quant-ph | null | We investigate the separability of arbitrary $n$-dimensional multipartite
identical bosonic systems. An explicit relation between the dimension and the
separability is presented. In particular, for $n=3$, it is shown that the
property of PPT (positive partial transpose) and the separability are
equivalent for tripartite systems.
| [
{
"version": "v1",
"created": "Sat, 19 Aug 2006 08:30:37 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Wang",
"Xiao-Hong",
""
],
[
"Fei",
"Shao-Ming",
""
],
[
"Wu",
"Ke",
""
]
]
|
quant-ph/0608152 | Gong Zhe-Xuan | Zhe-Xuan Gong | Effective error-suppression scheme for reversible quantum computer | 6 pages, 5 figures | null | null | null | quant-ph | null | We construct a new error-suppression scheme that makes use of the adjoint of
reversible quantum algorithms. For decoherence induced errors such as
depolarization, it is presented that provided the depolarization error
probability is less than 1, our scheme can exponentially reduce the final
output error rate to zero using a number of cycles, and the output state can be
coherently sent to another stage of quantum computation process. Besides,
experimental set-ups via optical approach have been proposed using Grover's
search algorithm as an example. Some further discussion on the benefits and
limitations of the scheme is given in the end.
| [
{
"version": "v1",
"created": "Sun, 20 Aug 2006 03:28:33 GMT"
},
{
"version": "v2",
"created": "Thu, 14 Sep 2006 05:23:36 GMT"
},
{
"version": "v3",
"created": "Fri, 24 Nov 2006 02:45:15 GMT"
},
{
"version": "v4",
"created": "Tue, 28 Nov 2006 12:38:25 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Gong",
"Zhe-Xuan",
""
]
]
|
quant-ph/0608153 | Giulio Chiribella | G. Chiribella, G. M. D'Ariano, C. Macchiavello, P. Perinotti, and F.
Buscemi | Superbroadcasting and classical information | 9 pages, 2 figures | Phys. Rev. A 75, 012315 (2007) | 10.1103/PhysRevA.75.012315 | null | quant-ph | null | We address the problem of broadcasting N copies of a generic qubit state to
M>N copies by estimating its direction and preparing a suitable output state
according to the outcome of the estimate. This semiclassical broadcasting
protocol is more restrictive than a general one, since it requires an
intermediate step where classical information is extracted and processed.
However, we prove that a suboptimal superbroadcasting, namely broadcasting with
simultaneous purification of the local output states with respect to the input
ones, is possible. We show that in the asymptotic limit of $M \to \infty$ the
purification rate converges to the optimal one, proving the conjecture that
optimal broadcasting and state estimation are asymptotically equivalent. We
also show that it is possible to achieve superbroadcasting with simultaneous
inversion of the Bloch vector direction (universal NOT). We prove that in this
case the semiclassical procedure of state estimation and preparation turns out
to be optimal. We finally analyse semiclassical superbroadcasting in the
phase-covariant case.
| [
{
"version": "v1",
"created": "Sun, 20 Aug 2006 16:57:02 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Chiribella",
"G.",
""
],
[
"D'Ariano",
"G. M.",
""
],
[
"Macchiavello",
"C.",
""
],
[
"Perinotti",
"P.",
""
],
[
"Buscemi",
"F.",
""
]
]
|
quant-ph/0608154 | Satoshi Morita | Satoshi Morita and Hidetoshi Nishimori | Convergence theorems for quantum annealing | 19 pages | J. Phys. A: Math. Gen. 39 (2006) 13903 | 10.1088/0305-4470/39/45/004 | null | quant-ph cond-mat.dis-nn cond-mat.stat-mech | null | We prove several theorems to give sufficient conditions for convergence of
quantum annealing, which is a protocol to solve generic optimization problems
by quantum dynamics. In particular the property of strong ergodicity is proved
for the path-integral Monte Carlo implementation of quantum annealing for the
transverse Ising model under a power decay of the transverse field. This result
is to be compared with the much slower inverse-log decay of temperature in the
conventional simulated annealing. Similar results are proved for the Green's
function Monte Carlo approach. Optimization problems in continuous space of
particle configurations are also discussed.
| [
{
"version": "v1",
"created": "Mon, 21 Aug 2006 05:00:11 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Morita",
"Satoshi",
""
],
[
"Nishimori",
"Hidetoshi",
""
]
]
|
quant-ph/0608155 | Kenichiro Furuta | Kenichiro Furuta | Improving the efficiency of decoding quantum error correction code | null | null | null | null | quant-ph | null | To improve the efficiency of the encoding and the decoding is the important
problem in the quantum error correction. In a preceding work, a general
algorithm for decoding the stabilizer code is shown. This paper will show an
decoding which is more efficient for some codes. The proposed decoding as well
as the conventional decoding consists of the eigenvalue output step and the
entanglement dissolution step. The proposed decoding outputs a part of the
eigenvalues into a part of the code qubits in contrast to the conventional
method's outputting into the ancilla. Besides, the proposed decoding dissolves
a part of the entanglement in the eigenvalue output step in contrast to the
conventional method which does not dissolve in the eigenvalue output step. With
these improvements, the number of gates was reduced for some codes.
| [
{
"version": "v1",
"created": "Mon, 21 Aug 2006 05:15:24 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Furuta",
"Kenichiro",
""
]
]
|
quant-ph/0608156 | Boaz Tamir | B. Tamir | Communication Complexity Protocol for Q-trits | 8 pages | null | 10.1103/PhysRevA.75.032344 | null | quant-ph | null | Consider a function where its entries are distributed among many parties.
Suppose each party is allowed to transmit only a limited amount of information
to a net. One can use a classical protocol to guess the value of the global
function. Is there a quantum protocol improving the results of all classical
protocols? Brukner et. al. showed the deep connection between such problems and
the theory of Bell's inequalities. Here we generalize the theory to trits.
There the best classical protocol fails whereas the quantum protocol yields the
correct answer.
| [
{
"version": "v1",
"created": "Mon, 21 Aug 2006 07:33:30 GMT"
}
]
| 2015-06-26T00:00:00 | [
[
"Tamir",
"B.",
""
]
]
|
quant-ph/0608157 | Marco Barbieri | Marco Barbieri, Francesco De Martini, Paolo Mataloni, Giuseppe
Vallone, Ad\'an Cabello | Enhancing the Violation of the Einstein-Podolsky-Rosen Local Realism by
Quantum Hyper-entanglement | Minor errors corrected. To appear on Physical Review Letters | Phys. Rev. Lett. 97, 140407 (2006) | 10.1103/PhysRevLett.97.140407 | null | quant-ph | null | Mermin's observation [Phys. Rev. Lett. {\bf 65}, 1838 (1990)] that the
magnitude of the violation of local realism, defined as the ratio between the
quantum prediction and the classical bound, can grow exponentially with the
size of the system is demonstrated using two-photon hyper-entangled states
entangled in polarization and path degrees of freedom, and local measurements
of polarization and path simultaneously.
| [
{
"version": "v1",
"created": "Mon, 21 Aug 2006 08:10:32 GMT"
},
{
"version": "v2",
"created": "Mon, 28 Aug 2006 14:49:03 GMT"
}
]
| 2009-10-29T00:00:00 | [
[
"Barbieri",
"Marco",
""
],
[
"De Martini",
"Francesco",
""
],
[
"Mataloni",
"Paolo",
""
],
[
"Vallone",
"Giuseppe",
""
],
[
"Cabello",
"Adán",
""
]
]
|
quant-ph/0608158 | Lucas Lamata | L. Lamata, J.J. Garcia-Ripoll, J.I. Cirac | How much entanglement can be generated between two atoms by detecting
photons? | 4 pages, 3 figures, minor improvements, references added, accepted in
PRL | Phys. Rev. Lett. 98, 010502 (2007) | 10.1103/PhysRevLett.98.010502 | null | quant-ph | null | It is possible to achieve an arbitrary amount of entanglement between two
atoms using only spontaneously emitted photons, linear optics, single photon
sources and projective measurements. This is in contrast to all current
experimental proposals for entangling two atoms, which are fundamentally
restricted to one entanglement bit or ebit.
| [
{
"version": "v1",
"created": "Mon, 21 Aug 2006 15:49:45 GMT"
},
{
"version": "v2",
"created": "Tue, 14 Nov 2006 09:12:47 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Lamata",
"L.",
""
],
[
"Garcia-Ripoll",
"J. J.",
""
],
[
"Cirac",
"J. I.",
""
]
]
|
quant-ph/0608159 | Stephanie Manz | Stephanie Manz, Thomas Fernholz, Joerg Schmiedmayer, and Jian-Wei Pan | Collisional decoherence during writing and reading quantum states | four pages, three figures (minor changes, added references) | Phys. Rev. A 75, 040101(R) (2007) | 10.1103/PhysRevA.75.040101 | null | quant-ph | null | Collisions, even though they do not limit the lifetime of quantum information
stored in ground state hyperfine coherences, may severely limit the fidelity
for quantum memory when they happen during the write and read process. This
imposes restrictions on the implementation of quantum processes in thermal
vapor cells and their performance as a quantum memory. We study the effect of
these collisions in our experiment.
| [
{
"version": "v1",
"created": "Mon, 21 Aug 2006 15:56:54 GMT"
},
{
"version": "v2",
"created": "Tue, 22 Aug 2006 09:26:23 GMT"
},
{
"version": "v3",
"created": "Thu, 19 Apr 2007 20:00:48 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Manz",
"Stephanie",
""
],
[
"Fernholz",
"Thomas",
""
],
[
"Schmiedmayer",
"Joerg",
""
],
[
"Pan",
"Jian-Wei",
""
]
]
|
quant-ph/0608160 | Fernando Semi\~ao | F. L. Semi\~ao, R. J. Missori, and K. Furuya | Unconditional Bell-type state generation for spatially separate trapped
ions | 5 pages, 1 figure, detailed comments on the practical implementation
of the scheme is added to replaced version, minor typos fixed, added
references with comments | J. Phys. B: At. Mol. Opt. Phys. 40, S221-S228 (2007) | 10.1088/0953-4075/40/9/S14 | null | quant-ph | null | We propose a scheme for generation of maximally entangled states involving
internal electronic degrees of freedom of two distant trapped ions, each of
them located in a cavity. This is achieved by using a single flying atom to
distribute entanglement. For certain specific interaction times, the proposed
scheme leads to the non-probabilistic generation of a perfect Bell-type state.
At the end of the protocol, the flying atom completely disentangles from the
rest of the system, leaving both ions in a Bell-type state. Moreover, the
scheme is insensitive to the cavity field state and cavity losses. We also
address the situation in which dephasing and dissipation must be taken into
account for the flying atom on its way from one cavity to the other, and
discuss the applicability of the resulting noisy channel for performing quantum
teleportation.
| [
{
"version": "v1",
"created": "Mon, 21 Aug 2006 20:23:35 GMT"
},
{
"version": "v2",
"created": "Thu, 24 Aug 2006 20:28:31 GMT"
},
{
"version": "v3",
"created": "Mon, 30 Apr 2007 18:34:09 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Semião",
"F. L.",
""
],
[
"Missori",
"R. J.",
""
],
[
"Furuya",
"K.",
""
]
]
|
quant-ph/0608161 | Andrew J. Landahl | Andrew M. Childs, Andrew J. Landahl, Pablo A. Parrilo | Improved quantum algorithms for the ordered search problem via
semidefinite programming | 8 pages, 4 figures | Phys. Rev. A 75, 032335 (2007) | 10.1103/PhysRevA.75.032335 | null | quant-ph | null | One of the most basic computational problems is the task of finding a desired
item in an ordered list of N items. While the best classical algorithm for this
problem uses log_2 N queries to the list, a quantum computer can solve the
problem using a constant factor fewer queries. However, the precise value of
this constant is unknown. By characterizing a class of quantum query algorithms
for ordered search in terms of a semidefinite program, we find new quantum
algorithms for small instances of the ordered search problem. Extending these
algorithms to arbitrarily large instances using recursion, we show that there
is an exact quantum ordered search algorithm using 4 log_{605} N \approx 0.433
log_2 N queries, which improves upon the previously best known exact algorithm.
| [
{
"version": "v1",
"created": "Mon, 21 Aug 2006 21:34:20 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Childs",
"Andrew M.",
""
],
[
"Landahl",
"Andrew J.",
""
],
[
"Parrilo",
"Pablo A.",
""
]
]
|
quant-ph/0608162 | Rubens Ramos Viana | Jose Claudio do Nascimento, Fabio Alencar Mendonca, Rubens Viana Ramos | Linear optical setups for active and passive quantum error correction in
polarization encoded qubits | 14 pages, 5 figures | null | null | null | quant-ph | null | In this work, we present active and passive linear optical setups for error
correction in quantum communication systems that employ polarization of
single-photon and mesoscopic coherent states. Applications in quantum
communication systems are described.
| [
{
"version": "v1",
"created": "Mon, 21 Aug 2006 22:02:13 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Nascimento",
"Jose Claudio do",
""
],
[
"Mendonca",
"Fabio Alencar",
""
],
[
"Ramos",
"Rubens Viana",
""
]
]
|
quant-ph/0608163 | Kam Wai Clifford Chan | K.W. Chan, J.P. Torres, J.H. Eberly | Transverse Entanglement Migration in Hilbert Space | 4 pages, 3 figures | null | 10.1103/PhysRevA.75.050101 | null | quant-ph | null | We show that, although the amount of mutual entanglement of photons
propagating in free space is fixed, the type of correlations between the
photons that determine the entanglement can dramatically change during
propagation. We show that this amounts to a migration of entanglement in
Hilbert space, rather than real space. For the case of spontaneous parametric
down conversion, the migration of entanglement in transverse coordinates takes
place from modulus to phase of the bi-photon state and back again. We propose
an experiment to observe this migration in Hilbert space and to determine the
full entanglement.
| [
{
"version": "v1",
"created": "Mon, 21 Aug 2006 22:53:56 GMT"
},
{
"version": "v2",
"created": "Wed, 18 Apr 2007 18:03:50 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Chan",
"K. W.",
""
],
[
"Torres",
"J. P.",
""
],
[
"Eberly",
"J. H.",
""
]
]
|
quant-ph/0608164 | Susana F. Huelga | Susana Huelga (UH) and Martin Plenio (Imperial College London) | Stochastic Resonance Phenomena in Quantum Many-Body Systems | Replaced with published version | Phys. Rev. Lett. 98,170601 (2007) | 10.1103/PhysRevLett.98.170601 | null | quant-ph | null | We discuss stochastic resonance (SR) effects in driven coupled quantum
systems. We construct dynamical and information theoretic measures of the
system's response that exhibit a non-monotonic behaviour as a function of the
noise strength. We analyze the relation between lack of monotonicity in the
response and the presence of quantum correlations and identify parameter
regimes where the breakdown of a linear response can be linked to the presence
of entanglement. We also show that a chain of coupled spin systems can exhibit
an array-enhanced response, where the sensitivity of a single resonator is
enhanced as a result of nearest-neighbour coupling. These results enlarge the
domain where SR effects exist and should be observable in arrays of
superconducting qubits.
| [
{
"version": "v1",
"created": "Mon, 21 Aug 2006 23:02:01 GMT"
},
{
"version": "v2",
"created": "Wed, 25 Apr 2007 13:10:58 GMT"
}
]
| 2013-05-29T00:00:00 | [
[
"Huelga",
"Susana",
"",
"UH"
],
[
"Plenio",
"Martin",
"",
"Imperial College London"
]
]
|
quant-ph/0608165 | Minh Dung Dang | Minh-Dung Dang | Two-party Models and the No-go Theorems | 9 pages, 8 figures. Due to attacks received from reviewers, an
important case-study on "coin-flipping-based protocols" is removed. Comments
are welcome | null | null | null | quant-ph | null | In this paper, we reconsider the communication model used in the no-go
theorems on the impossibility of quantum bit commitment and oblivious transfer.
We state that a macroscopic classical channel may not be replaced with a
quantum channel which is used in the reduced model proving the no-go theorems.
We show that in some restricted cases, the reduced model is insecure while the
original model with a classical channel is secure.
| [
{
"version": "v1",
"created": "Tue, 22 Aug 2006 09:03:43 GMT"
},
{
"version": "v2",
"created": "Wed, 30 Aug 2006 17:32:09 GMT"
},
{
"version": "v3",
"created": "Sun, 24 Sep 2006 16:55:39 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Dang",
"Minh-Dung",
""
]
]
|
quant-ph/0608166 | Adan Cabello | Adan Cabello | Bipartite Bell inequalities for hyperentangled states | REVTeX4, 5 pages | Phys. Rev. Lett. 97 (2006) 140406 | 10.1103/PhysRevLett.97.140406 | null | quant-ph | null | We show that bipartite Bell inequalities based on the Einstein-Podolsky-Rosen
criterion for elements of reality and derived from the properties of some
hyperentangled states allow feasible experimental verifications of the fact
that quantum nonlocality grows exponentially with the size of the subsystems,
and Bell loophole-free tests with currently available photodetection
efficiencies.
| [
{
"version": "v1",
"created": "Tue, 22 Aug 2006 11:33:55 GMT"
},
{
"version": "v2",
"created": "Wed, 30 Aug 2006 02:32:25 GMT"
},
{
"version": "v3",
"created": "Sat, 7 Oct 2006 15:44:29 GMT"
}
]
| 2009-07-28T00:00:00 | [
[
"Cabello",
"Adan",
""
]
]
|
quant-ph/0608167 | Thomas Marlow | Thomas Marlow | Natural Philosophy and Quantum Theory | 7 pages | null | null | null | quant-ph | null | We attempt to show how relationalism might help in understanding Bell's
theorem. We also present an analogy with Darwinian evolution in order to
pedagogically hint at how one might go about using a theory in which one does
not even desire to explain correlations by invoking common causes.
| [
{
"version": "v1",
"created": "Tue, 22 Aug 2006 13:34:31 GMT"
},
{
"version": "v2",
"created": "Wed, 25 Oct 2006 14:33:29 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Marlow",
"Thomas",
""
]
]
|
quant-ph/0608168 | Robabeh Rahimi Darabad | Robabeh Rahimi, Akira SaiToh, Mikio Nakahara, and Masahiro Kitagawa | Single-experiment-detectable multipartite entanglement witness for
ensemble quantum computing | 9 pages, 5 figures, minor changes have been made | Phys. Rev. A 75, 032317 (2007) | 10.1103/PhysRevA.75.032317 | null | quant-ph | null | In this paper we provide an operational method to detect multipartite
entanglement in ensemble-based quantum computing. This method is based on the
concept of entanglement witness. We decompose the entanglement witness for each
class of multipartite entanglement into nonlocal operations in addition to
local measurements. Individual single qubit measurements are performed
simultaneously, hence complete detection of entanglement is performed in a
single run experiment. This approach is particularly important for experiments
where it is operationally difficult to prepare several copies of an unknown
quantum state and in this sense the introduced scheme in this work is superior
to the generally used entanglement witnesses that require a number of
experiments and preparation of copies of quantum state.
| [
{
"version": "v1",
"created": "Tue, 22 Aug 2006 15:01:41 GMT"
},
{
"version": "v2",
"created": "Thu, 31 Aug 2006 13:28:08 GMT"
},
{
"version": "v3",
"created": "Fri, 29 Dec 2006 08:31:57 GMT"
},
{
"version": "v4",
"created": "Tue, 13 Mar 2007 08:24:18 GMT"
}
]
| 2015-06-26T00:00:00 | [
[
"Rahimi",
"Robabeh",
""
],
[
"SaiToh",
"Akira",
""
],
[
"Nakahara",
"Mikio",
""
],
[
"Kitagawa",
"Masahiro",
""
]
]
|
quant-ph/0608169 | Seyyad Yahya Mirafzali | S.Y. Mirafzali, M. Sarbishaei | The effect of anisotropy and external magnetic filed on the thermal
entanglement in a two-spin-qutrit system | 5 pages, 3 figures | null | null | null | quant-ph | null | We study the thermal entanglement in a two-spin-qutrit system with anisotropy
in the exchange coupling between two spins. We use the realignment criterion to
distinguish the entangled states, and the negativity for measuring the
entanglement in this system. We see that the anisotropy can provide an
additional parameter for enhancing the entanglement.
| [
{
"version": "v1",
"created": "Tue, 22 Aug 2006 20:10:03 GMT"
}
]
| 2019-08-15T00:00:00 | [
[
"Mirafzali",
"S. Y.",
""
],
[
"Sarbishaei",
"M.",
""
]
]
|
quant-ph/0608170 | Kam Wai Clifford Chan | Girish S. Agarwal, Kam Wai Chan, Robert W. Boyd, Hugo Cable, Jonathan
P. Dowling | Quantum States of Light Produced by a High-Gain Optical Parametric
Amplifier for Use in Quantum Lithography | 7 pages, 6 figures | J. Opt. Soc. Am. B 24, 270 (2007) | 10.1364/JOSAB.24.000270 | null | quant-ph | null | We present a theoretical analysis of the properties of an unseeded optical
parametic amplifier (OPA) used as the source of entangled photons for
applications in quantum lithography. We first study the dependence of the
excitation rate of a two-photon absorber on the intensity of the light leaving
the OPA. We find that the rate depends linearly on intensity only for output
beams so weak that they contain fewer than one photon per mode. We also study
the use of an N-photon absorber for arbitrary N as the recording medium to be
used with such a light source. We find that the contrast of the interference
pattern and the sharpness of the fringe maxima tend to increase with increasing
values of N, but that the density of fringes and thus the limiting resolution
does not increase with N. We conclude that the output of an unseeded OPA
exciting an N-photon absorber provides an attractive system in which to perform
quantum lithography.
| [
{
"version": "v1",
"created": "Tue, 22 Aug 2006 21:28:18 GMT"
}
]
| 2015-06-26T00:00:00 | [
[
"Agarwal",
"Girish S.",
""
],
[
"Chan",
"Kam Wai",
""
],
[
"Boyd",
"Robert W.",
""
],
[
"Cable",
"Hugo",
""
],
[
"Dowling",
"Jonathan P.",
""
]
]
|
quant-ph/0608171 | Alex D. Gottlieb | Alex D. Gottlieb, Norbert J. Mauser | Properties of nonfreeness: an entropy measure of electron correlation | 20 pages. Submitted to Phys. Rev. B | null | null | null | quant-ph | null | "Nonfreeness" is the (negative of the) difference between the von Neumann
entropies of a given many-fermion state and the free state that has the same
1-particle statistics. It also equals the relative entropy of the two states in
question, i.e., it is the entropy of the given state relative to the
corresponding free state. The nonfreeness of a pure state is the same as its
"particle-hole symmetric correlation entropy", a variant of an established
measure of electron correlation. But nonfreeness is also defined for mixed
states, and this allows one to compare the nonfreeness of subsystems to the
nonfreeness of the whole. Nonfreeness of a part does not exceed that in the
whole; nonfreeness is additive over independent subsystems; and nonfreeness is
superadditive over subsystems that are independent on the 1-particle level.
| [
{
"version": "v1",
"created": "Wed, 23 Aug 2006 02:26:00 GMT"
},
{
"version": "v2",
"created": "Thu, 31 Aug 2006 01:29:45 GMT"
},
{
"version": "v3",
"created": "Tue, 21 Nov 2006 01:44:13 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Gottlieb",
"Alex D.",
""
],
[
"Mauser",
"Norbert J.",
""
]
]
|
quant-ph/0608172 | Akira Saitoh | Akira SaiToh and Robabeh Rahimi | Population-only decay map for n-qubit n-partite inseparability detection | 5 pages, 1 figure, RevTex4, v2 minor grammatical changes, typos
corrected | Phys. Rev. A 74, 064305 (2006) | 10.1103/PhysRevA.74.064305 | null | quant-ph | null | We introduce a new positive linear map for a single qubit. This map is a
decay only in populations of a single-qubit density operator. It is shown that
an n-fold product of this map may be used for a detection of n-partite
inseparability of an n-qubit density operator (i.e., detection of impossibility
of representing a density operator in the form of a convex combination of
products of density operators of individual qubits). This product map is also
investigated in relation to a variant of the entanglement detection method
mentioned by Laskowski and Zukowski.
| [
{
"version": "v1",
"created": "Wed, 23 Aug 2006 05:38:22 GMT"
},
{
"version": "v2",
"created": "Thu, 16 Nov 2006 05:20:17 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"SaiToh",
"Akira",
""
],
[
"Rahimi",
"Robabeh",
""
]
]
|
quant-ph/0608173 | Luis L. Sanchez. Soto | Gunnar Bjork, Jose L. Romero, Andrei B. Klimov and Luis L.
Sanchez-Soto | Mutually unbiased bases and discrete Wigner functions | 9 pages, 6 tables, 6 figures. Accepted for publication in J. Opt.
Soc. Am. B, special issue on Optical Quantum Information Science | J. Opt. Soc. Am. B 24, 371--378 (2007) | 10.1364/JOSAB.24.000371 | null | quant-ph | null | Mutually unbiased bases and discrete Wigner functions are closely, but not
uniquely related. Such a connection becomes more interesting when the Hilbert
space has a dimension that is a power of a prime $N=d^n$, which describes a
composite system of $n$ qudits. Hence, entanglement naturally enters the
picture. Although our results are general, we concentrate on the simplest
nontrivial example of dimension $N=8=2^3$. It is shown that the number of
fundamentally different Wigner functions is severely limited if one
simultaneously imposes translational covariance and that the generating
operators consist of rotations around two orthogonal axes, acting on the
individual qubits only.
| [
{
"version": "v1",
"created": "Wed, 23 Aug 2006 06:54:24 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Bjork",
"Gunnar",
""
],
[
"Romero",
"Jose L.",
""
],
[
"Klimov",
"Andrei B.",
""
],
[
"Sanchez-Soto",
"Luis L.",
""
]
]
|
quant-ph/0608174 | Goren Gordon | Goren Gordon and Gershon Kurizki | Preventing Multipartite Disentanglement by Local Modulations | 5 pages, 2 figures | null | 10.1103/PhysRevLett.97.110503 | null | quant-ph | null | An entangled multipartite system coupled to a zero-temperature bath undergoes
rapid disentanglement in many realistic scenarios, due to local,
symmetry-breaking, differences in the particle-bath couplings. We show that
locally controlled perturbations, addressing each particle individually, can
impose a symmetry, and thus allow the existence of decoherence-free
multipartite entangled systems in zero-temperature environments.
| [
{
"version": "v1",
"created": "Wed, 23 Aug 2006 09:19:50 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Gordon",
"Goren",
""
],
[
"Kurizki",
"Gershon",
""
]
]
|
quant-ph/0608175 | Goren Gordon | Goren Gordon, Gershon Kurizki and Abraham G. Kofman | Universal Dynamical Control of Local Decoherence for Multipartite and
Multilevel Systems | 22 pages, 6 figures | Optics Communications 264, 398 (2006) | 10.1016/j.optcom.2006.01.062 | null | quant-ph | null | A unified theory is given of dynamically modified decay and decoherence of
field-driven multilevel multipartite entangled states that are weakly coupled
to zero-temperature baths or undergo random phase fluctuations. The theory
allows for arbitrary local differences in their coupling to the environment.
Due to such differences, the optimal driving-field modulation to ensure maximal
fidelity is found to substantially differ from conventional ``Bang-Bang'' or
$\pi$-phase flips of the single-qubit evolution.
| [
{
"version": "v1",
"created": "Wed, 23 Aug 2006 10:02:41 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Gordon",
"Goren",
""
],
[
"Kurizki",
"Gershon",
""
],
[
"Kofman",
"Abraham G.",
""
]
]
|
quant-ph/0608176 | Akbar Fahmi Shakib | A. Fahmi and M. Golshani | Transition of D- Level Quantum Systems Through Quantum Channels with
Correlated Noise | 15 pages, 5 figures, PHYSICAL REVIEW A 75, 042301 (2007) | PHYSICAL REVIEW A 75, 042301 (2007) | 10.1103/PhysRevA.75.042301 | null | quant-ph | null | Entanglement and entanglement-assisted are useful resources to enhance the
mutual information of the Pauli channels, when the noise on consecutive uses of
the channel has some partial correlations. In this Paper, we study
quantum-communication channels in $d$-dimensional systems and derive the mutual
information of the quantum channels for maximally entangled states and product
states coding with correlated noise. Then, we compare fidelity between these
states. Our results show that there exists a certain fidelity memory threshold
which depends on the dimension of the Hilbert space $(d)$ and the properties of
noisy channels. We calculate the classical capacity of a particular correlated
noisy channel and show that in order to achieve Holevo limit, we must use $d$
particles with $d$ degrees of freedom. Our results show that entanglement is a
useful means to enhance the mutual information. We choose a special
non-maximally entangled state and show that in the quasi-classical depolarizing
and quantum depolarizing channels, maximum classical capacity in the higher
memory channels is given by the maximally entangled state. Hence, our results
show that for high error channels in every degree of memory, maximally
entangled states have better mutual information.
| [
{
"version": "v1",
"created": "Wed, 23 Aug 2006 10:48:50 GMT"
},
{
"version": "v2",
"created": "Tue, 3 Apr 2007 07:12:22 GMT"
},
{
"version": "v3",
"created": "Wed, 4 Apr 2007 06:03:27 GMT"
}
]
| 2015-06-26T00:00:00 | [
[
"Fahmi",
"A.",
""
],
[
"Golshani",
"M.",
""
]
]
|
quant-ph/0608177 | Dimiter Trifonov | O. Cherbal, M. Drir, M. Maamache, and D.A. Trifonov | Fermionic coherent states for pseudo-Hermitian two-level systems | 13 pages (Latex, article class), no figures; v2: some amendments in
section 2, seven new refs added | J. Phys. A 40 (2007) 1835-1844 | 10.1088/1751-8113/40/8/010 | null | quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We introduce creation and annihilation operators of pseudo-Hermitian fermions
for two-level systems described by pseudo-Hermitian Hamiltonian with real
eigenvalues. This allows the generalization of the fermionic coherent states
approach to such systems. Pseudo-fermionic coherent states are constructed as
eigenstates of two pseudo-fermion annihilation operators. These coherent states
form a bi-normal and bi-overcomplete system, and their evolution governed by
the pseudo-Hermitian Hamiltonian is temporally stable. In terms of the
introduced pseudo-fermion operators the two-level system' Hamiltonian takes a
factorized form similar to that of a harmonic oscillator.
| [
{
"version": "v1",
"created": "Wed, 23 Aug 2006 12:57:39 GMT"
},
{
"version": "v2",
"created": "Fri, 27 Feb 2009 10:26:26 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Cherbal",
"O.",
""
],
[
"Drir",
"M.",
""
],
[
"Maamache",
"M.",
""
],
[
"Trifonov",
"D. A.",
""
]
]
|
quant-ph/0608178 | Andrew A. Semenov | A.A. Semenov, W. Vogel, M. Khanbekyan, D.-G. Welsch | Determination of quantum-noise parameters of realistic cavities | 5 pages, 2 figures | Phys. Rev. A 75, 013807 (2007) | 10.1103/PhysRevA.75.013807 | null | quant-ph physics.optics | null | A procedure is developed which allows one to measure all the parameters
occurring in a complete model [A.A. Semenov et al., Phys. Rev. A 74, 033803
(2006); quant-ph/0603043] of realistic leaky cavities with unwanted noise. The
method is based on the reflection of properly chosen test pulses by the cavity.
| [
{
"version": "v1",
"created": "Wed, 23 Aug 2006 13:53:22 GMT"
},
{
"version": "v2",
"created": "Fri, 19 Jan 2007 08:46:55 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Semenov",
"A. A.",
""
],
[
"Vogel",
"W.",
""
],
[
"Khanbekyan",
"M.",
""
],
[
"Welsch",
"D. -G.",
""
]
]
|
quant-ph/0608179 | Hongwei Yu | Hongwei Yu and Zhiying Zhu | Spontaneous absorption of an accelerated hydrogen atom near a conducting
plane in vacuum | 19 pages, no figures, Revtex4 | Phys.Rev. D74 (2006) 044032 | 10.1103/PhysRevD.74.044032 | null | quant-ph gr-qc hep-th | null | We study, in the multipolar coupling scheme, a uniformly accelerated
multilevel hydrogen atom in interaction with the quantum electromagnetic field
near a conducting boundary and separately calculate the contributions of the
vacuum fluctuation and radiation reaction to the rate of change of the mean
atomic energy. It is found that the perfect balance between the contributions
of vacuum fluctuations and radiation reaction that ensures the stability of
ground-state atoms is disturbed, making spontaneous transition of ground-state
atoms to excited states possible in vacuum with a conducting boundary. The
boundary-induced contribution is effectively a nonthermal correction, which
enhances or weakens the nonthermal effect already present in the unbounded
case, thus possibly making the effect easier to observe. An interesting feature
worth being noted is that the nonthermal corrections may vanish for atoms on
some particular trajectories.
| [
{
"version": "v1",
"created": "Wed, 23 Aug 2006 14:01:07 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Yu",
"Hongwei",
""
],
[
"Zhu",
"Zhiying",
""
]
]
|
quant-ph/0608180 | Asish Ganguly | David J. Fernandez C. and Asish Ganguly | Exactly solvable associated Lame potentials and supersymmetric
transformations | Annals of Phys.(in press); Present e-mail of AG:
[email protected] | AnnalsPhys.322:1143-1161,2007 | 10.1016/j.aop.2006.07.011 | null | quant-ph hep-th math-ph math.MP | null | A systematic procedure to derive exact solutions of the associated Lame
equation for an arbitrary value of the energy is presented. Supersymmetric
transformations in which the seed solutions have factorization energies inside
the gaps are used to generate new exactly solvable potentials; some of them
exhibit an interesting property of periodicity defects.
| [
{
"version": "v1",
"created": "Wed, 23 Aug 2006 15:34:13 GMT"
}
]
| 2008-11-26T00:00:00 | [
[
"C.",
"David J. Fernandez",
""
],
[
"Ganguly",
"Asish",
""
]
]
|
quant-ph/0608181 | Marco Merkli | M. Merkli, I.M. Sigal, G.P. Berman | Decoherence and Thermalization | null | null | 10.1103/PhysRevLett.98.130401 | null | quant-ph math-ph math.MP | null | We present a rigorous analysis of the phenomenon of decoherence for general
N-level systems coupled to reservoirs of free massless bosonic fields. We apply
our general results to the specific case of the qubit. Our approach does not
involve master equation approximations and applies to a wide variety of systems
which are not explicitly solvable.
| [
{
"version": "v1",
"created": "Wed, 23 Aug 2006 18:10:44 GMT"
}
]
| 2015-06-26T00:00:00 | [
[
"Merkli",
"M.",
""
],
[
"Sigal",
"I. M.",
""
],
[
"Berman",
"G. P.",
""
]
]
|
quant-ph/0608182 | Eric Charron | Eric Charron (PPM), P\'erola Milman (PPM, CERMICS), Arne Keller (PPM),
Osman Atabek (PPM) | Quantum phase gate and controlled entanglement with polar molecules | null | Physical Review A / Physical Review A (General Physics); Phys Rev
A Gen Phys; Physical Review A (Atomic Molecular and Optical Physics) 75, 3
(26/03/2007) 033414 | 10.1103/PhysRevA.75.033414 | null | quant-ph | null | We propose an alternative scenario for the generation of entanglement between
rotational quantum states of two polar molecules. This entanglement arises from
dipole-dipole interaction, and is controlled by a sequence of laser pulses
simultaneously exciting both molecules. We study the efficiency of the process,
and discuss possible experimental implementations with cold molecules trapped
in optical lattices or in solid matrices. Finally, various entanglement
detection procedures are presented, and their suitability for these two
physical situations is analyzed.
| [
{
"version": "v1",
"created": "Wed, 23 Aug 2006 18:15:27 GMT"
},
{
"version": "v2",
"created": "Thu, 1 Feb 2007 14:59:10 GMT"
}
]
| 2016-08-16T00:00:00 | [
[
"Charron",
"Eric",
"",
"PPM"
],
[
"Milman",
"Pérola",
"",
"PPM, CERMICS"
],
[
"Keller",
"Arne",
"",
"PPM"
],
[
"Atabek",
"Osman",
"",
"PPM"
]
]
|
quant-ph/0608183 | Felix Bussieres | Felix Bussieres, Yasaman Soudagar, Guido Berlin, Suzanne Lacroix,
Nicolas Godbout | Deterministic unitary operations on time-bin qudits for quantum
communication | 4 pages, 5 figures. One figure replaced | null | null | null | quant-ph | null | We show for the first time how deterministic unitary operations on time-bin
qubits encoded in single photon pulses can be realized using fiber optics
components that are available with current technology. We also generalize this
result to operations on time-bin qudits, i.e. $d$-level systems, and show that
this can be done efficiently using 2$\times$2 beamsplitters and phase
modulators. Important benefits for experimental quantum communication are
highlighted. This work shows how to bridge the gap between current
proof-of-principle demonstrations and complete, deterministic experiments.
| [
{
"version": "v1",
"created": "Wed, 23 Aug 2006 19:52:51 GMT"
},
{
"version": "v2",
"created": "Wed, 23 Aug 2006 20:19:43 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Bussieres",
"Felix",
""
],
[
"Soudagar",
"Yasaman",
""
],
[
"Berlin",
"Guido",
""
],
[
"Lacroix",
"Suzanne",
""
],
[
"Godbout",
"Nicolas",
""
]
]
|
quant-ph/0608184 | Gustavo Garcia Rigolin | Gustavo Rigolin and Marcos C. de Oliveira | Quantification of Continuous Variable Entanglement with only Two Types
of Simple Measurements | v1: 4 pages, 1 figure, RevTex4; v2: Title and abstract changed, new
discussion paragraph added; v3: published version | Annals of Physics 323, 2172 (2008) | 10.1016/j.aop.2008.01.004 | null | quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Here we propose an experimental set-up in which it is possible to measure the
entanglement of a two-mode Gaussian state, be it pure or mixed, using only
simple linear optical devices. After a proper unitary manipulation of the
two-mode Gaussian state only number and purity measurements of just one of the
modes suffice to give us a complete and exact knowledge of the state's
entanglement.
| [
{
"version": "v1",
"created": "Wed, 23 Aug 2006 20:10:47 GMT"
},
{
"version": "v2",
"created": "Tue, 6 Feb 2007 17:07:01 GMT"
},
{
"version": "v3",
"created": "Tue, 12 Aug 2008 04:29:13 GMT"
}
]
| 2015-06-26T00:00:00 | [
[
"Rigolin",
"Gustavo",
""
],
[
"de Oliveira",
"Marcos C.",
""
]
]
|
quant-ph/0608185 | Johan Aberg | Johan Aberg, David Kult, Erik Sj\"oqvist, and D.K.L. Oi | Operational approach to the Uhlmann holonomy | Added material, references, and journal references | Physical Review A 75, 032106 (2007) | 10.1103/PhysRevA.75.032106 | null | quant-ph | null | We suggest a physical interpretation of the Uhlmann amplitude of a density
operator. Given this interpretation we propose an operational approach to
obtain the Uhlmann condition for parallelity. This allows us to realize
parallel transport along a sequence of density operators by an iterative
preparation procedure. At the final step the resulting Uhlmann holonomy can be
determined via interferometric measurements.
| [
{
"version": "v1",
"created": "Thu, 24 Aug 2006 16:14:10 GMT"
},
{
"version": "v2",
"created": "Sat, 10 Mar 2007 13:09:03 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Aberg",
"Johan",
""
],
[
"Kult",
"David",
""
],
[
"Sjöqvist",
"Erik",
""
],
[
"Oi",
"D. K. L.",
""
]
]
|
quant-ph/0608186 | Kazuyuki Fujii | Kazuyuki Fujii, Hiroshi Oike and Tatsuo Suzuki | More on the Isomorphism $SU(2)\otimes SU(2)\cong SO(4)$ | Latex ; 19 pages ; 5 figures ; minor changes. To appear in
International Journal of Geometric Methods in Modern Physics (vol.4, no.3) | Int.J.Geom.Meth.Mod.Phys.4:471-485,2007 | 10.1142/S0219887807002120 | null | quant-ph hep-th math-ph math.MP | null | In this paper we revisit the isomorphism $SU(2)\otimes SU(2)\cong SO(4)$ to
apply to some subjects in Quantum Computation and Mathematical Physics.
The unitary matrix $Q$ by Makhlin giving the isomorphism as an adjoint action
is studied and generalized from a different point of view. Some problems are
also presented.
In particular, the homogeneous manifold $SU(2n)/SO(2n)$ which characterizes
entanglements in the case of $n=2$ is studied, and a clear-cut calculation of
the universal Yang-Mills action in (hep-th/0602204) is given for the abelian
case.
| [
{
"version": "v1",
"created": "Thu, 24 Aug 2006 01:17:07 GMT"
},
{
"version": "v2",
"created": "Fri, 12 Jan 2007 01:17:49 GMT"
}
]
| 2008-11-26T00:00:00 | [
[
"Fujii",
"Kazuyuki",
""
],
[
"Oike",
"Hiroshi",
""
],
[
"Suzuki",
"Tatsuo",
""
]
]
|
quant-ph/0608187 | Jia Xiaojun | Xiaolong Su, Aihong Tan, Xiaojun Jia*, Jing Zhang, Changde Xie, Kunchi
Peng | Experimental Preparation of Quadripartite Cluster and GHZ Entangled
States for Continuous Variables | null | Phys. Rev. Lett. 98, 070502(2007) | 10.1103/PhysRevLett.98.070502 | null | quant-ph | null | The cluster states and Greenberger-Horne-Zeilinger (GHZ) states are two
different types of multipartite quantum entangled states. We present the first
experimental results generating continuous variable quadripartite cluster and
GHZ entangled states of electromagnetic fields. Utilizing four two-mode
squeezed states of light and linearly optical transformations, the two types of
entangled states for amplitude and phase quadratures of light are
experimentally produced. The combinations of the measured quadrature variances
prove the full inseparability of the generated four subsystems. The presented
experimental schemes show that the multipartite entanglement of continuous
variables can be deterministically generated with the relatively simple
implementation.
| [
{
"version": "v1",
"created": "Thu, 24 Aug 2006 01:32:13 GMT"
}
]
| 2015-06-26T00:00:00 | [
[
"Su",
"Xiaolong",
""
],
[
"Tan",
"Aihong",
""
],
[
"Jia*",
"Xiaojun",
""
],
[
"Zhang",
"Jing",
""
],
[
"Xie",
"Changde",
""
],
[
"Peng",
"Kunchi",
""
]
]
|
quant-ph/0608188 | Yoshiaki Rikitake | Yoshiaki Rikitake and Hiroshi Imamura | Effect of exchange interaction on fidelity of quantum state transfer
from a photon qubit to an electron-spin qubit | 5 pages, 4 figures, to be published in Phys. Rev. B Rapid
Communications | null | 10.1103/PhysRevB.74.081307 | null | quant-ph | null | We analyzed the fidelity of the quantum state transfer (QST) from a
photon-polarization qubit to an electron-spin-polarization qubit in a
semiconductor quantum dot, with special attention to the exchange interaction
between the electron and the simultaneously created hole. In order to realize a
high-fidelity QST we had to separate the electron and hole as soon as possible,
since the electron-hole exchange interaction modifies the orientation of the
electron spin. Thus, we propose a double-dot structure to separate the electron
and hole quickly, and show that the fidelity of the QST can reach as high as
0.996 if the resonant tunneling condition is satisfied.
| [
{
"version": "v1",
"created": "Thu, 24 Aug 2006 06:52:33 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Rikitake",
"Yoshiaki",
""
],
[
"Imamura",
"Hiroshi",
""
]
]
|
quant-ph/0608189 | Ressa Said | R.S. Said, M.R.B. Wahiddin and B.A. Umarov | Squeezing in multi-mode nonlinear optical state truncation | 7 pages, 5 eps figures. Revised manuscript. Accepted for publication
in Phys. Lett. A | Phys. Lett. A, 365 (2007) 380-385 | 10.1016/j.physleta.2007.01.042 | null | quant-ph | null | In this paper, we show that multi-mode qubit states produced via nonlinear
optical state truncation driven by classical external pumpings exhibit
squeezing condition. We restrict our discussions to the two and three-mode
cases.
| [
{
"version": "v1",
"created": "Thu, 24 Aug 2006 09:18:38 GMT"
},
{
"version": "v2",
"created": "Fri, 25 Aug 2006 03:41:05 GMT"
},
{
"version": "v3",
"created": "Mon, 11 Sep 2006 10:49:20 GMT"
},
{
"version": "v4",
"created": "Wed, 17 Jan 2007 06:33:53 GMT"
}
]
| 2009-03-10T00:00:00 | [
[
"Said",
"R. S.",
""
],
[
"Wahiddin",
"M. R. B.",
""
],
[
"Umarov",
"B. A.",
""
]
]
|
quant-ph/0608190 | Ruediger Schack | Carlton M. Caves, Christopher A. Fuchs, Ruediger Schack | Subjective probability and quantum certainty | 20 pages RevTeX, 1 figure, extensive changes in response to referees'
comments | null | null | null | quant-ph | null | In the Bayesian approach to quantum mechanics, probabilities--and thus
quantum states--represent an agent's degrees of belief, rather than
corresponding to objective properties of physical systems. In this paper we
investigate the concept of certainty in quantum mechanics. Particularly, we
show how the probability-1 predictions derived from pure quantum states
highlight a fundamental difference between our Bayesian approach, on the one
hand, and Copenhagen and similar interpretations on the other. We first review
the main arguments for the general claim that probabilities always represent
degrees of belief. We then argue that a quantum state prepared by some physical
device always depends on an agent's prior beliefs, implying that the
probability-1 predictions derived from that state also depend on the agent's
prior beliefs. Quantum certainty is therefore always some agent's certainty.
Conversely, if facts about an experimental setup could imply agent-independent
certainty for a measurement outcome, as in many Copenhagen-like
interpretations, that outcome would effectively correspond to a preexisting
system property. The idea that measurement outcomes occurring with certainty
correspond to preexisting system properties is, however, in conflict with
locality. We emphasize this by giving a version of an argument of Stairs [A.
Stairs, Phil. Sci. 50, 578 (1983)], which applies the Kochen-Specker theorem to
an entangled bipartite system.
| [
{
"version": "v1",
"created": "Thu, 24 Aug 2006 10:23:44 GMT"
},
{
"version": "v2",
"created": "Fri, 26 Jan 2007 16:26:57 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Caves",
"Carlton M.",
""
],
[
"Fuchs",
"Christopher A.",
""
],
[
"Schack",
"Ruediger",
""
]
]
|
quant-ph/0608191 | Gustavo Lopez | Gustavo V. Lopez and Lorena Lara | Simulation of an entangled state in a chain of three nuclear spins
system | 8 pages, 6 figures | null | null | null | quant-ph | null | We study the formation of an entangled state in a one-dimensional chain of
three nuclear spins system which interact weakly through the Ising type of
interaction and taking into account first and second neighbor interactions. We
can get this entangled state using two pulses ($\pi/2$ and $\pi$ pulses), and
we study the efficiency of getting this entangled state as a function of the
ratio of the second neighbor interaction coupling constant to the first
neighbor interaction coupling constant ($J'/J$). We found that for $J'/J\ge
0.04$, the entangled state is well defined.
| [
{
"version": "v1",
"created": "Thu, 24 Aug 2006 14:43:24 GMT"
},
{
"version": "v2",
"created": "Mon, 28 Aug 2006 22:26:19 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Lopez",
"Gustavo V.",
""
],
[
"Lara",
"Lorena",
""
]
]
|
quant-ph/0608192 | Thiago Rodrigues de Oliveira | Thiago R. de Oliveira and A. O. Caldeira | Coherence and Entanglement in a Stern-Gerlach experiment | null | null | null | null | quant-ph | null | We give a simple example of the tight connection between entanglement and
coherence for pure bipartite systems showing the double role played by
entanglement; it allows for the creation of superpositions of macroscopic
objects but at the same time makes subsystems lose their quantum mechanical
coherence. For this we study the time evolution of the spin coherence in the
Stern-Gerlach (SG) experiment. We also show that, contrary to the naive
intuition, the spin coherence is lost before the two beams become separated in
the spatial coordinates.
| [
{
"version": "v1",
"created": "Thu, 24 Aug 2006 20:49:11 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"de Oliveira",
"Thiago R.",
""
],
[
"Caldeira",
"A. O.",
""
]
]
|
quant-ph/0608193 | Fernando Semi\~ao | F.L. Semi\~ao and A. Vidiella-Barranco | Two-photon interaction between trapped ions and cavity fields | 9 pages, 10 figures | Eur. Phys. J. D 41, 417 (2007) | 10.1140/epjd/e2006-00243-7 | null | quant-ph | null | In this paper, we generalize the ordinary two-photon Jaynes-Cummings model
(TPJCM) by considering the atom (or ion) to be trapped in a simple harmonic
well. A typical setup would be an optical cavity containing a single ion in a
Paul trap. Due to the inclusion of atomic vibrational motion, the atom-field
coupling becomes highly nonlinear what brings out quite different behaviors for
the system dynamics when compared to the ordinary TPJCM. In particular, we
derive an effective two-photon Hamiltonian with dependence on the number
operator of the ion's center-of-mass motion. This dependence occurs both in the
cavity induced Stark-shifs and in the ion-field coupling, and its role in the
dynamics is illustrated by showing the time evolution of the probability of
occupation of the electronic levels for simple initial preparations of the
state of the system.
| [
{
"version": "v1",
"created": "Thu, 24 Aug 2006 21:50:29 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Semião",
"F. L.",
""
],
[
"Vidiella-Barranco",
"A.",
""
]
]
|
quant-ph/0608194 | Gustavo Lopez | Gustavo V. Lopez and Lorena Lara | Numerical simulation of Quantum Teleportation in a chain of three
nuclear spins system taking into account second neighbor interaction | 11 pages, 7 figures | null | null | null | quant-ph | null | For a one-dimensional chain of three nuclear spins (one half), we make the
numerical simulation of quantum teleportation of a given state from one end of
the chain to the other end, taking into account first and second neighbor
interactions among the spins. It is shown that a well defined teleportation
protocol is achieved for a ratio of the first to second neighbor interaction
coupling constant of $J'/J\ge 0.04$. We also show that the optimum Rabi's
frequency to control the non-resonant effects is dominated by the second
neighbor interaction coupling parameter ($J'$).
| [
{
"version": "v1",
"created": "Thu, 24 Aug 2006 23:20:16 GMT"
},
{
"version": "v2",
"created": "Mon, 28 Aug 2006 22:34:04 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Lopez",
"Gustavo V.",
""
],
[
"Lara",
"Lorena",
""
]
]
|
quant-ph/0608195 | Debbie W. Leung | Karol Horodecki, Michal Horodecki, Pawel Horodecki, Debbie Leung,
Jonathan Oppenheim | Quantum key distribution based on private states: unconditional security
over untrusted channels with zero quantum capacity | Final version for IEEE TIT | IEEE Transactions on Information Theory Vol 54 Issue 6 p2604-2620
(2008) | 10.1109/TIT.2008.921870 | null | quant-ph | null | We prove unconditional security for a quantum key distribution (QKD) protocol
based on distilling pbits (twisted ebits) [quant-ph/0309110] from an arbitrary
untrusted state that is claimed to contain distillable key. Our main result is
that we can verify security using only public communication -- via parameter
estimation of the given untrusted state. The technique applies even to bound
entangled states, thus extending QKD to the regime where the available quantum
channel has zero quantum capacity. We also show how to convert our
purification-based QKD schemes to prepare-measure schemes.
| [
{
"version": "v1",
"created": "Fri, 25 Aug 2006 00:04:48 GMT"
},
{
"version": "v2",
"created": "Thu, 14 Dec 2006 20:50:07 GMT"
},
{
"version": "v3",
"created": "Tue, 7 Aug 2007 02:53:11 GMT"
},
{
"version": "v4",
"created": "Tue, 9 Oct 2007 19:37:41 GMT"
}
]
| 2016-11-18T00:00:00 | [
[
"Horodecki",
"Karol",
""
],
[
"Horodecki",
"Michal",
""
],
[
"Horodecki",
"Pawel",
""
],
[
"Leung",
"Debbie",
""
],
[
"Oppenheim",
"Jonathan",
""
]
]
|
quant-ph/0608196 | Tomoyuki Morimae | Tomoyuki Morimae, Akira Shimizu | Visualization of superposition of macroscopically distinct states | 12pages, 21figures | Phys. Rev. A 74, 052111 (2006) | 10.1103/PhysRevA.74.052111 | null | quant-ph | null | We propose a method of visualizing superpositions of macroscopically distinct
states in many-body pure states. We introduce a visualization function, which
is a coarse-grained quasi joint probability density for two or more hermitian
additive operators. If a state contains superpositions of macroscopically
distinct states, one can visualize them by plotting the visualization function
for appropriately taken operators. We also explain how to efficiently find
appropriate operators for a given state. As examples, we visualize four states
containing superpositions of macroscopically distinct states: the ground state
of the XY model, that of the Heisenberg antiferromagnet, a state in Shor's
factoring algorithm, and a state in Grover's quantum search algorithm. Although
the visualization function can take negative values, it becomes non-negative
(hence becomes a coarse-grained joint probability density) if the
characteristic width of the coarse-graining function used in the visualization
function is sufficiently large.
| [
{
"version": "v1",
"created": "Fri, 25 Aug 2006 05:34:06 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Morimae",
"Tomoyuki",
""
],
[
"Shimizu",
"Akira",
""
]
]
|
quant-ph/0608197 | David Perez-Garcia | D. Perez-Garcia, F. Verstraete, M.M. Wolf, J.I. Cirac | Matrix Product State Representations | Minor changes. To appear in QIC | Quantum Inf. Comput. 7, 401 (2007) | null | null | quant-ph | null | This work gives a detailed investigation of matrix product state (MPS)
representations for pure multipartite quantum states. We determine the freedom
in representations with and without translation symmetry, derive respective
canonical forms and provide efficient methods for obtaining them. Results on
frustration free Hamiltonians and the generation of MPS are extended, and the
use of the MPS-representation for classical simulations of quantum systems is
discussed.
| [
{
"version": "v1",
"created": "Fri, 25 Aug 2006 09:05:11 GMT"
},
{
"version": "v2",
"created": "Mon, 14 May 2007 16:05:27 GMT"
}
]
| 2007-08-02T00:00:00 | [
[
"Perez-Garcia",
"D.",
""
],
[
"Verstraete",
"F.",
""
],
[
"Wolf",
"M. M.",
""
],
[
"Cirac",
"J. I.",
""
]
]
|
quant-ph/0608198 | Masahito Hayashi | Masahito Hayashi | Quantum estimation and the quantum central limit theorem | The original Japanese version of this manuscript was published as an
introductory article of quantum estimation in Bulletin of Mathematical
Society of Japan, Sugaku, Vol. 55, No. 4, 368--391 (2003); Received September
2, 2002, Published October 24, 2003. It was translated to English by
Michikazu Sato and Masahito Hayashi. The essential content of this manuscript
is the same as that of the original version, while several descriptions and
references are improved. The material in this paper was presented in English
in part at Joint MaPhySto and QUANTOP Workshop on Quantum Measurements and
Quantum Stochastics, Department of Mathematical Sciences, University of
Aarhus, Denmark, 2003, Non-locality of Quantum Mechanics and Statistical
Inference, Kyoto Sangyo Univ., Kyoto, 2003, and Special Week on Quantum
Statistics, Isaac Newton Institute for Mathematical Sciences, Cambridge, UK,
2004 | American Mathematical Society Translations Series 2, Vol. 277, pp
95 - 123 (2009) | null | null | quant-ph | null | This paper gives a survey about quantum estimation. We also describes the
relation between the quantum central limit theorem and the asymptotic bound of
mean square error in quantum state estimation.
| [
{
"version": "v1",
"created": "Fri, 25 Aug 2006 11:50:22 GMT"
}
]
| 2009-11-18T00:00:00 | [
[
"Hayashi",
"Masahito",
""
]
]
|
quant-ph/0608199 | Renato Renner | Matthias Christandl and Artur Ekert and Michal Horodecki and Pawel
Horodecki and Jonathan Oppenheim and Renato Renner | Unifying classical and quantum key distillation | full version | Proceedings of the 4th Theory of Cryptography Conference, Lecture
Notes in Computer Science vol. 4392, pp. 456-478, 2007 | null | null | quant-ph | null | Assume that two distant parties, Alice and Bob, as well as an adversary, Eve,
have access to (quantum) systems prepared jointly according to a tripartite
state. In addition, Alice and Bob can use local operations and authenticated
public classical communication. Their goal is to establish a key which is
unknown to Eve. We initiate the study of this scenario as a unification of two
standard scenarios: (i) key distillation (agreement) from classical
correlations and (ii) key distillation from pure tripartite quantum states.
Firstly, we obtain generalisations of fundamental results related to
scenarios (i) and (ii), including upper bounds on the key rate. Moreover, based
on an embedding of classical distributions into quantum states, we are able to
find new connections between protocols and quantities in the standard scenarios
(i) and (ii).
Secondly, we study specific properties of key distillation protocols. In
particular, we show that every protocol that makes use of pre-shared key can be
transformed into an equally efficient protocol which needs no pre-shared key.
This result is of practical significance as it applies to quantum key
distribution (QKD) protocols, but it also implies that the key rate cannot be
locked with information on Eve's side. Finally, we exhibit an arbitrarily large
separation between the key rate in the standard setting where Eve is equipped
with quantum memory and the key rate in a setting where Eve is only given
classical memory. This shows that assumptions on the nature of Eve's memory are
important in order to determine the correct security threshold in QKD.
| [
{
"version": "v1",
"created": "Fri, 25 Aug 2006 16:25:50 GMT"
},
{
"version": "v2",
"created": "Thu, 21 Dec 2006 13:27:14 GMT"
},
{
"version": "v3",
"created": "Wed, 28 Feb 2007 09:11:14 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Christandl",
"Matthias",
""
],
[
"Ekert",
"Artur",
""
],
[
"Horodecki",
"Michal",
""
],
[
"Horodecki",
"Pawel",
""
],
[
"Oppenheim",
"Jonathan",
""
],
[
"Renner",
"Renato",
""
]
]
|
quant-ph/0608200 | Cecilia Cormick | Cecilia Cormick and Juan Pablo Paz | Interference in discrete Wigner functions | 10 pages, 5 figures | Phys. Rev. A 74, 062315 (2006) (9 pages) | 10.1103/PhysRevA.74.062315 | null | quant-ph | null | We analyse some features of the class of discrete Wigner functions that was
recently introduced by Gibbons et al. to represent quantum states of systems
with power-of-prime dimensional Hilbert spaces [Phys. Rev. A 70, 062101
(2004)]. We consider "cat" states obtained as coherent superpositions of states
with positive Wigner function; for such states we show that the oscillations of
the discrete Wigner function typically spread over the entire discrete
phase-space (including the regions where the two interfering states are
localized). This is a generic property which is in sharp contrast with the
usual attributes of Wigner functions that make them useful candidates to
display the existence of quantum coherence through oscillations. However, it is
possible to find subsets of cat states with a natural phase-space
representation, in which the oscillatory regions remain localized. We show that
this can be done for interesting families of stabilizer states used in quantum
error-correcting codes, and illustrate this by analysing the phase-space
representation of the five-qubit error-correcting code.
| [
{
"version": "v1",
"created": "Fri, 25 Aug 2006 19:22:33 GMT"
}
]
| 2008-03-31T00:00:00 | [
[
"Cormick",
"Cecilia",
""
],
[
"Paz",
"Juan Pablo",
""
]
]
|
quant-ph/0608201 | Barbara Synak-Radtke | Barbara Synak-Radtke, Lukasz Pankowski, Michal Horodecki and Ryszard
Horodecki | On some entropic entanglement parameter | 9 pages, 1 figure, revtex | null | null | null | quant-ph | null | In this paper we present the quantity, which is an entanglement parameter.
Its origin is very intriguing, because its construction is motivated by
separability criteria based on uncertainty relation. We show that this quantity
is asymptotically continuous. We also find the lower and upper bounds for it.
Our entanglement parameter has the same feature as the coherent information:
both can be negative.
There are also some classes of states for which these quantities coincide
with each other.
| [
{
"version": "v1",
"created": "Fri, 25 Aug 2006 21:50:05 GMT"
}
]
| 2016-09-08T00:00:00 | [
[
"Synak-Radtke",
"Barbara",
""
],
[
"Pankowski",
"Lukasz",
""
],
[
"Horodecki",
"Michal",
""
],
[
"Horodecki",
"Ryszard",
""
]
]
|
quant-ph/0608202 | Paul O'Hara | Paul O'Hara | Entanglement and quantum interference | 4 pages, 1 .eps file | null | null | NEIU 06-0825 | quant-ph | null | In the history of quantum mechanics, much has been written about the
double-slit experiment, and much debate as to its interpretation has ensued.
Indeed, to explain the interference patterns for sub-atomic particles,
explanations have been given not only in terms of the principle of
complementarity and wave-particle duality but also in terms of quantum
consciousness and parallel universes. In this paper, the topic will be
discussed from the perspective of spin-coupling in the hope of further
clarification. We will also suggest that this explanation allows for a realist
interpretation of the Afshar Experiment.
| [
{
"version": "v1",
"created": "Sat, 26 Aug 2006 03:44:39 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"O'Hara",
"Paul",
""
]
]
|
quant-ph/0608203 | H. T Cui | H. T. Cui, K. Li, X. X. Yi | Geometric Phase and Quantum Phase Transition in the Lipkin-Meshkov-Glick
model | 6 pages and to be published in Phys.Lett.A | Physics Letters A 360 (2006) 243?C248 | 10.1016/j.physleta.2006.08.040 | null | quant-ph | null | The relation between the geometric phase and quantum phase transition has
been discussed in the Lipkin-Meshkov-Glick model. Our calculation shows the
ability of geometric phase of the ground state to mark quantum phase transition
in this model. The possibility of the geometric phase or its derivatives as the
universal order parameter of characterizing quantum phase transitions has been
also discussed.
| [
{
"version": "v1",
"created": "Sat, 26 Aug 2006 04:48:17 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Cui",
"H. T.",
""
],
[
"Li",
"K.",
""
],
[
"Yi",
"X. X.",
""
]
]
|
quant-ph/0608204 | Salomon S. Mizrahi | M. A. de Ponte, S. S. Mizrahi, and M. H. Y. Moussa | Relaxation- and Decoherence-free subspaces in networks of weakly and
strongly coupled resonators | 5 pages | null | 10.1016/j.aop.2007.03.001 | null | quant-ph | null | We consider a network of interacting resonators and analyze the physical
ingredients that enable the emergence of relaxation-free and decoherence-free
subspaces. We investigate two different situations: i) when the whole network
interacts with a common reservoir and ii) when each resonator, strongly coupled
to each other, interacts with its own reservoir. Our main result is that both
subspaces are generated when all the resonators couple with the same group of
reservoir modes, thus building up a correlation (among these modes), which has
the potential to shield particular network states against relaxation and/or
decoherence.
| [
{
"version": "v1",
"created": "Sat, 26 Aug 2006 21:18:22 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"de Ponte",
"M. A.",
""
],
[
"Mizrahi",
"S. S.",
""
],
[
"Moussa",
"M. H. Y.",
""
]
]
|
quant-ph/0608205 | J. Q. You | Xiang-bin Wang, J. Q. You, Franco Nori | Measurement-based quantum computation with superconducting charge qubits | 4 pages, 1 figure | null | null | null | quant-ph cond-mat.mes-hall cond-mat.supr-con | null | We present a robust method, based only on measurements, to produce
superconducting cluster states. The measurement of the current of a few
parallel Josephson-junction qubits realizes a novel type of quantum-state
selector. Using this selector, one can produce various quantum entangled states
and also realize a controlled-NOT gate without requiring an exact control of
the interqubit interactions. In particular, cluster states for quantum
computation could be produced with only single-qubit measurements.
| [
{
"version": "v1",
"created": "Sun, 27 Aug 2006 05:33:43 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Wang",
"Xiang-bin",
""
],
[
"You",
"J. Q.",
""
],
[
"Nori",
"Franco",
""
]
]
|
quant-ph/0608206 | James P. Crutchfield | Karoline Wiesner and James P. Crutchfield | Computation in Finitary Stochastic and Quantum Processes | 25 pages, 16 figures, 1 table; http://cse.ucdavis.edu/~cmg; numerous
corrections and updates | null | null | Santa Fe Institute Working Paper 06-09-031 | quant-ph | null | We introduce stochastic and quantum finite-state transducers as
computation-theoretic models of classical stochastic and quantum finitary
processes. Formal process languages, representing the distribution over a
process's behaviors, are recognized and generated by suitable specializations.
We characterize and compare deterministic and nondeterministic versions,
summarizing their relative computational power in a hierarchy of finitary
process languages. Quantum finite-state transducers and generators are a first
step toward a computation-theoretic analysis of individual, repeatedly measured
quantum dynamical systems. They are explored via several physical systems,
including an iterated beam splitter, an atom in a magnetic field, and atoms in
an ion trap--a special case of which implements the Deutsch quantum algorithm.
We show that these systems' behaviors, and so their information processing
capacity, depends sensitively on the measurement protocol.
| [
{
"version": "v1",
"created": "Sun, 27 Aug 2006 19:00:26 GMT"
},
{
"version": "v2",
"created": "Fri, 3 Aug 2007 23:09:34 GMT"
},
{
"version": "v3",
"created": "Mon, 17 Dec 2007 14:25:08 GMT"
},
{
"version": "v4",
"created": "Mon, 28 Apr 2008 22:19:02 GMT"
}
]
| 2008-04-29T00:00:00 | [
[
"Wiesner",
"Karoline",
""
],
[
"Crutchfield",
"James P.",
""
]
]
|
quant-ph/0608207 | Gang Chen | Gang Chen, Juqi Li, J.-Q. Liang | Critical Property of Geometric Phase in the Dicke Model | 1 figure | null | 10.1103/PhysRevA.74.054101 | null | quant-ph | null | We obtain the ground-state energy level and associated geometric phase in the
Dicke model analytically by means of the Holstein-Primakoff transformation and
the boson expansion approach in the thermodynamic limit. The non-adiabatic
geometric phase induced by the photon field is derived with the time-dependent
unitary transformation. It is shown that the quantum phase transition
characterized by the non-analyticity of the geometric phase is remarkably of
the first-order. We also investigate the scaling behavior of the geometric
phase at the critical point, which can be measured in a practical experiment to
detect the quantum phase transition.
| [
{
"version": "v1",
"created": "Mon, 28 Aug 2006 06:22:41 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Chen",
"Gang",
""
],
[
"Li",
"Juqi",
""
],
[
"Liang",
"J. -Q.",
""
]
]
|
quant-ph/0608208 | Mahmoud Abdel-Aty | Mahmoud Abdel-Aty, M. R. B. Wahiddin and A.-S. F. Obada | Generation of three-qubit entangled states using coupled multi-quantum
dots | 8 pages, 2 figures | null | 10.1002/lapl.200610126 | null | quant-ph | null | We discuss a mechanism for generating a maximum entangled state (GHZ) in a
coupled quantum dots system, based on analytical techniques. The reliable
generation of such states is crucial for implementing solid-state based quantum
information schemes. The signature originates from a remarkably weak field
pulse or a far off-resonance effects which could be implemented using
technology that is currently being developed. The results are illustrated with
an application to a specific wide-gap semiconductor quantum dots system, like
Zinc Selenide (ZnSe) based quantum dots.
| [
{
"version": "v1",
"created": "Mon, 28 Aug 2006 06:55:55 GMT"
}
]
| 2015-06-26T00:00:00 | [
[
"Abdel-Aty",
"Mahmoud",
""
],
[
"Wahiddin",
"M. R. B.",
""
],
[
"Obada",
"A. -S. F.",
""
]
]
|
quant-ph/0608209 | Hongbao Zhang | Yi Ling, Song He, Weigang Qiu, and Hongbao Zhang | Quantum Entanglement of Electromagnetic Fields in Non-inertial Reference
Frames | more explanatory material added in the introduction, version to
appear in Journal of Physics A | J.Phys.A40:9025-9032,2007 | 10.1088/1751-8113/40/30/024 | null | quant-ph gr-qc hep-th | null | Recently relativistic quantum information has received considerable attention
due to its theoretical importance and practical application. Especially,
quantum entanglement in non-inertial reference frames has been studied for
scalar and Dirac fields. As a further step along this line, we here shall
investigate quantum entanglement of electromagnetic fields in non-inertial
reference frames. In particular, the entanglement of photon helicity entangled
state is extensively analyzed. Interestingly, the resultant logarithmic
negativity and mutual information remain the same as those for inertial
reference frames, which is completely different from that previously obtained
for the particle number entangled state.
| [
{
"version": "v1",
"created": "Mon, 28 Aug 2006 08:03:14 GMT"
},
{
"version": "v2",
"created": "Wed, 30 Aug 2006 11:36:50 GMT"
},
{
"version": "v3",
"created": "Mon, 4 Sep 2006 08:54:55 GMT"
},
{
"version": "v4",
"created": "Thu, 3 May 2007 03:54:58 GMT"
},
{
"version": "v5",
"created": "Fri, 8 Jun 2007 03:47:24 GMT"
}
]
| 2008-11-26T00:00:00 | [
[
"Ling",
"Yi",
""
],
[
"He",
"Song",
""
],
[
"Qiu",
"Weigang",
""
],
[
"Zhang",
"Hongbao",
""
]
]
|
quant-ph/0608210 | Bo Wang | Bo Wang, Yanxu Han, Jintao Xiao, Xudong Yang, Changde Xie, Hai Wang,
Min Xiao | Multi-dark-state resonances in cold multi-Zeeman-sublevel atoms | 11pages, 4figures | null | 10.1364/OL.31.003647 | null | quant-ph | null | We present our experimental and theoretical studies of multi-dark-state
resonances (MDSRs) generated in a unique cold rubidium atomic system with only
one coupling laser beam. Such MDSRs are caused by different transition
strengths of the strong coupling beam connecting different Zeeman sublevels.
Controlling the transparency windows in such electromagnetically induced
transparency system can have potential applications in multi-wavelength optical
communication and quantum information processing.
| [
{
"version": "v1",
"created": "Mon, 28 Aug 2006 08:32:01 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Wang",
"Bo",
""
],
[
"Han",
"Yanxu",
""
],
[
"Xiao",
"Jintao",
""
],
[
"Yang",
"Xudong",
""
],
[
"Xie",
"Changde",
""
],
[
"Wang",
"Hai",
""
],
[
"Xiao",
"Min",
""
]
]
|
quant-ph/0608211 | Koray Duztas | Ibrahim Semiz and Koray Duztas | On the exactness of the Semi-Classical Approximation for
Non-Relativistic One Dimensional Propagators | 7 pages, latex, no figures, published in journal of physics A | journal of physics A: Math. Gen. Vol:39 p.14681, 2006 | 10.1088/0305-4470/39/47/011 | null | quant-ph | null | For one dimensional non-relativistic quantum mechanical problems, we
investigate the conditions for all the position dependence of the propagator to
be in its phase, that is, the semi-classical approximation to be exact. For
velocity independent potentials we find that:
(i) the potential must be quadratic in space, but can have arbitrary time
dependence.
(ii) the phase may be made proportional to the classical action, and the
magnitude (``fluctuation factor'') can also be found from the classical
solution.
(iii) for the driven harmonic oscillator the fluctuation factor is
independent of the driving term.
| [
{
"version": "v1",
"created": "Mon, 28 Aug 2006 09:18:42 GMT"
},
{
"version": "v2",
"created": "Thu, 16 Nov 2006 15:25:31 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Semiz",
"Ibrahim",
""
],
[
"Duztas",
"Koray",
""
]
]
|
quant-ph/0608212 | Sahel Ashhab | S. Ashhab, J. R. Johansson, Franco Nori | Decoherence in a scalable adiabatic quantum computer | 6 pages (two-column), 1 figure | Phys. Rev. A 74, 052330 (2006) | 10.1103/PhysRevA.74.052330 | null | quant-ph cond-mat.other | null | We consider the effects of decoherence on Landau-Zener crossings encountered
in a large-scale adiabatic-quantum-computing setup. We analyze the dependence
of the success probability, i.e. the probability for the system to end up in
its new ground state, on the noise amplitude and correlation time. We determine
the optimal sweep rate that is required to maximize the success probability. We
then discuss the scaling of decoherence effects with increasing system size. We
find that those effects can be important for large systems, even if they are
small for each of the small building blocks.
| [
{
"version": "v1",
"created": "Mon, 28 Aug 2006 09:45:59 GMT"
},
{
"version": "v2",
"created": "Wed, 22 Nov 2006 06:55:28 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Ashhab",
"S.",
""
],
[
"Johansson",
"J. R.",
""
],
[
"Nori",
"Franco",
""
]
]
|
quant-ph/0608213 | Joanna Duligall | J. L. Duligall, M. S. Godfrey, K. A. Harrison, W. J. Munro, J. G.
Rarity | Low Cost and Compact Quantum Cryptography | 18 pages, 9 figures, to be published in New Journal of Physics | New J. Phys. 8 (2006) 249 | 10.1088/1367-2630/8/10/249 | null | quant-ph | null | We present the design of a novel free-space quantum cryptography system,
complete with purpose-built software, that can operate in daylight conditions.
The transmitter and receiver modules are built using inexpensive off-the-shelf
components. Both modules are compact allowing the generation of renewed shared
secrets on demand over a short range of a few metres. An analysis of the
software is shown as well as results of error rates and therefore shared secret
yields at varying background light levels. As the system is designed to
eventually work in short-range consumer applications, we also present a use
scenario where the consumer can regularly 'top up' a store of secrets for use
in a variety of one-time-pad and authentication protocols.
| [
{
"version": "v1",
"created": "Mon, 28 Aug 2006 10:59:22 GMT"
},
{
"version": "v2",
"created": "Tue, 3 Oct 2006 10:30:03 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Duligall",
"J. L.",
""
],
[
"Godfrey",
"M. S.",
""
],
[
"Harrison",
"K. A.",
""
],
[
"Munro",
"W. J.",
""
],
[
"Rarity",
"J. G.",
""
]
]
|
quant-ph/0608214 | Michael Fleischhauer | F. E. Zimmer, M. Fleischhauer | Quantum sensitivity limit of a Sagnac hybrid interferometer based on
slow-light propagation in ultra-cold gases | 12 pages, 6 figures | null | 10.1103/PhysRevA.74.063609 | null | quant-ph | null | The light--matter-wave Sagnac interferometer based on ultra-slow light
proposed recently in (Phys. Rev. Lett. 92, 253201 (2004)) is analyzed in
detail. In particular the effect of confining potentials is examined and it is
shown that the ultra-slow light attains a rotational phase shift equivalent to
that of a matter wave, if and only if the coherence transfer from light to
atoms associated with slow light is associated with a momentum transfer and if
an ultra-cold gas in a ring trap is used. The quantum sensitivity limit of the
Sagnac interferometer is determined and the minimum detectable rotation rate
calculated. It is shown that the slow-light interferometer allows for a
significantly higher signal-to-noise ratio as possible in current matter-wave
gyroscopes.
| [
{
"version": "v1",
"created": "Mon, 28 Aug 2006 12:33:59 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Zimmer",
"F. E.",
""
],
[
"Fleischhauer",
"M.",
""
]
]
|
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