id
stringlengths 9
16
| submitter
stringlengths 1
64
⌀ | authors
stringlengths 3
62.8k
| title
stringlengths 1
382
| comments
stringlengths 1
1.15k
⌀ | journal-ref
stringlengths 1
557
⌀ | doi
stringlengths 7
153
⌀ | report-no
stringlengths 1
509
⌀ | categories
stringlengths 5
125
| license
stringclasses 9
values | abstract
stringlengths 6
6.09k
| versions
listlengths 1
187
| update_date
timestamp[s]date 2007-05-23 00:00:00
2025-04-04 00:00:00
| authors_parsed
listlengths 1
2.83k
|
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
quant-ph/0701234 | Grzegorz Chimczak | Grzegorz Chimczak and Ryszard Tana\'s | Improving fidelity in atomic state teleportation via cavity decay | 8 pages, 7 figures, accepted for publication in Phys. Rev. A | Phys. Rev. A 75, 022317 (2007) | null | null | quant-ph | null | We propose a modified protocol of atomic state teleportation for the scheme
proposed by Bose et al. (Phys. Rev. Lett. 83, 5158 (1999)). The modified
protocol involves an additional stage in which quantum information distorted
during the first stage is fully recovered by a compensation of the damping
factor. The modification makes it possible to obtain a high fidelity of
teleported state for cavities that are much worse than that required in the
original protocol, i.e., their decay rates can be over 25 times larger. The
improvement in the fidelity is possible at the expense of lowering the
probability of success. We show that the modified protocol is robust against
dark counts.
| [
{
"version": "v1",
"created": "Tue, 30 Jan 2007 23:17:33 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Chimczak",
"Grzegorz",
""
],
[
"Tanaś",
"Ryszard",
""
]
]
|
quant-ph/0701235 | Luc Sanselme | G\'abor Ivanyos, Luc Sanselme and Miklos Santha | An efficient quantum algorithm for the hidden subgroup problem in
extraspecial groups | 10 pages | stacs 2007 | null | null | quant-ph | null | Extraspecial groups form a remarkable subclass of p-groups. They are also
present in quantum information theory, in particular in quantum error
correction. We give here a polynomial time quantum algorithm for finding hidden
subgroups in extraspecial groups. Our approach is quite different from the
recent algorithms presented in [17] and [2] for the Heisenberg group, the
extraspecial p-group of size p3 and exponent p. Exploiting certain nice
automorphisms of the extraspecial groups we define specific group actions which
are used to reduce the problem to hidden subgroup instances in abelian groups
that can be dealt with directly.
| [
{
"version": "v1",
"created": "Wed, 31 Jan 2007 01:07:52 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Ivanyos",
"Gábor",
""
],
[
"Sanselme",
"Luc",
""
],
[
"Santha",
"Miklos",
""
]
]
|
quant-ph/0701236 | Eyob Alebachew Sete | Eyob Alebachew and K. Fesseha | Degenerate three-level laser with parametric amplifier and squeezed
vacuum | null | null | null | null | quant-ph | null | Applying stochastic differential equations, we study the squeezing and
statistical properties of the cavity and output modes of a degenerate
three-level laser whose cavity contains a parametric amplifier and coupled to a
squeezed vacuum reservoir. We consider the case in which the top and bottom
levels of the three-level cascade atoms injected into the cavity are coupled by
the pump mode emerging from the parametric amplifier. It turns out that the
presence of the squeezed vacuum reservoir and the parametric amplifier
contribute considerably to the mean photon number and the degree of squeezing
of the cavity and output modes. It appears that almost perfect squeezing can be
achieved at steady state and at threshold for a suitable choice of parameters.
| [
{
"version": "v1",
"created": "Wed, 31 Jan 2007 05:23:46 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Alebachew",
"Eyob",
""
],
[
"Fesseha",
"K.",
""
]
]
|
quant-ph/0701237 | Tommaso Toffoli | Lev B. Levitin, Tommaso Toffoli | Thermodynamic cost of reversible computing | 5 pages; added two paragraphs and fixed a number of typos | null | 10.1103/PhysRevLett.99.110502 | null | quant-ph | null | Since reversible computing requires preservation of all information
throughout the entire computational process, this implies that all errors that
appear as a result of the interaction of the information-carrying system with
uncontrolled degrees of freedom must be corrected. But this can only be done at
the expense of an increase in the entropy of the environment corresponding to
the dissipation, in the form of heat, of the ``noisy'' part of the system's
energy.
This paper gives an expression of that energy in terms of the effective noise
temperature, and analyzes the relationship between the energy dissipation rate
and the rate of computation. Finally, a generalized Clausius principle based on
the concept of effective temperature is presented.
| [
{
"version": "v1",
"created": "Wed, 31 Jan 2007 08:23:38 GMT"
},
{
"version": "v2",
"created": "Wed, 6 Jun 2007 23:52:07 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Levitin",
"Lev B.",
""
],
[
"Toffoli",
"Tommaso",
""
]
]
|
quant-ph/0701238 | J\'er\^ome Lodewyck | Jerome Lodewyck, Thierry Debuisschert, Raul Garcia-Patron, Rosa
Tualle-Brouri, Nicolas J. Cerf and Philippe Grangier | Experimental implementation of non-Gaussian attacks on a
continuous-variable quantum key distribution system | 4 pages, 5 figures | Phys. Rev. Lett 98, 030503 (2007) | 10.1103/PhysRevLett.98.030503 | null | quant-ph | null | An intercept-resend attack on a continuous-variable quantum-key-distribution
protocol is investigated experimentally. By varying the interception fraction,
one can implement a family of attacks where the eavesdropper totally controls
the channel parameters. In general, such attacks add excess noise in the
channel, and may also result in non-Gaussian output distributions. We implement
and characterize the measurements needed to detect these attacks, and evaluate
experimentally the information rates available to the legitimate users and the
eavesdropper. The results are consistent with the optimality of Gaussian
attacks resulting from the security proofs.
| [
{
"version": "v1",
"created": "Wed, 31 Jan 2007 09:31:00 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Lodewyck",
"Jerome",
""
],
[
"Debuisschert",
"Thierry",
""
],
[
"Garcia-Patron",
"Raul",
""
],
[
"Tualle-Brouri",
"Rosa",
""
],
[
"Cerf",
"Nicolas J.",
""
],
[
"Grangier",
"Philippe",
""
]
]
|
quant-ph/0701239 | Christoph Simon | Christoph Simon, Hugues de Riedmatten, Mikael Afzelius, Nicolas
Sangouard, Hugo Zbinden, Nicolas Gisin | Quantum Repeaters with Photon Pair Sources and Multi-Mode Memories | 4 pages, 2 figures, to appear in PRL, accepted version | Phys. Rev. Lett. 98, 190503 (2007) | 10.1103/PhysRevLett.98.190503 | null | quant-ph | null | We propose a quantum repeater protocol which builds on the well-known DLCZ
protocol [L.M. Duan, M.D. Lukin, J.I. Cirac, and P. Zoller, Nature 414, 413
(2001)], but which uses photon pair sources in combination with memories that
allow to store a large number of temporal modes. We suggest to realize such
multi-mode memories based on the principle of photon echo, using solids doped
with rare-earth ions. The use of multi-mode memories promises a speedup in
entanglement generation by several orders of magnitude and a significant
reduction in stability requirements compared to the DLCZ protocol.
| [
{
"version": "v1",
"created": "Wed, 31 Jan 2007 12:07:45 GMT"
},
{
"version": "v2",
"created": "Thu, 5 Apr 2007 09:54:58 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Simon",
"Christoph",
""
],
[
"de Riedmatten",
"Hugues",
""
],
[
"Afzelius",
"Mikael",
""
],
[
"Sangouard",
"Nicolas",
""
],
[
"Zbinden",
"Hugo",
""
],
[
"Gisin",
"Nicolas",
""
]
]
|
quant-ph/0701240 | Ditte M{\o}ller | Ditte Moller, Lars Bojer Madsen and Klaus Molmer | Geometric phase gates based on stimulated Raman adiabatic passage in
tripod systems | 6 pages, 3 figures | null | 10.1103/PhysRevA.75.062302 | null | quant-ph | null | We consider stimulated Raman adiabatic passage (STIRAP) processes in tripod
systems and show how to generate purely geometric phase changes of the quantum
states involved. The geometric phases are controlled by three laser fields
where pulse shapes, relative field strength and phases can be controlled. We
present a robust set of universal gates for quantum computing based on these
geometric phases: a one-qubit phase gate, a Hadamard gate and a two-qubit phase
gate.
| [
{
"version": "v1",
"created": "Wed, 31 Jan 2007 12:13:41 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Moller",
"Ditte",
""
],
[
"Madsen",
"Lars Bojer",
""
],
[
"Molmer",
"Klaus",
""
]
]
|
quant-ph/0701241 | Miodrag Krmar | Vladan Pankovic, Milan Predojevic | Spontaneous Breaking of the Quantum Superposition | 17 pages, no figures | null | null | NS-Ph-2/07 | quant-ph | null | In this work spontaneous (non-dynamical) breaking (effective hiding) of the
unitary quantum mechanical dynamical symmetry (superposition) is considered. It
represents an especial but very interesting case of the general formalism of
the spontaneous symmetry breaking (effective hiding). Conceptual analogies with
spontaneous breaking of the gauge symmetry in Weinberg-Sallam's electro-weak
interaction are pointed out. Also, consequences of the spontaneous
superposition breaking in the measurement process are discussed. Measurement
can be considered as a typical Landau's continuous phase transition with
spontaneous superposition breaking (effective hiding) effectively corresponding
to collapse. Here critical values of the order parameters are determined by
Heisenberg's uncertainty relations.
| [
{
"version": "v1",
"created": "Wed, 31 Jan 2007 12:56:41 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Pankovic",
"Vladan",
""
],
[
"Predojevic",
"Milan",
""
]
]
|
quant-ph/0701242 | Alessandro Sergi | Alessandro Sergi | Deterministic constant-temperature dynamics for dissipative quantum
systems | Revised version | null | 10.1088/1751-8113/40/17/F05 | null | quant-ph | null | A novel method is introduced in order to treat the dissipative dynamics of
quantum systems interacting with a bath of classical degrees of freedom. The
method is based upon an extension of the Nos\`e-Hoover chain (constant
temperature) dynamics to quantum-classical systems. Both adiabatic and
nonadiabatic numerical calculations on the relaxation dynamics of the
spin-boson model show that the quantum-classical Nos\`e-Hoover chain dynamics
represents the thermal noise of the bath in an accurate and simple way.
Numerical comparisons, both with the constant energy calculation and with the
quantum-classical Brownian motion treatment of the bath, show that the
quantum-classical Nos\`e-Hoover Chain dynamics can be used to introduce
dissipation in the evolution of a quantum subsystem even with just one degree
of freedom for the bath. The algorithm can be computationally advantageous in
modeling, within computer simulation, the dynamics of a quantum subsystem
interacting with complex molecular environments.
| [
{
"version": "v1",
"created": "Wed, 31 Jan 2007 15:37:58 GMT"
},
{
"version": "v2",
"created": "Thu, 8 Mar 2007 11:47:37 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Sergi",
"Alessandro",
""
]
]
|
quant-ph/0701243 | Thomas B. Bahder | Thomas B. Bahder, Paul A. Lopata | Phase Sensitivity of a Mach-Zehnder Quantum Sensor | 4 pages, 4 figures | Conference proceedings of QCMC2006, The 8th International
Conference on Quantum Communication, Measurement, and Computing, Tsukuba,
Japan, 28th November - 3rd December, 2006 | null | null | quant-ph | null | We investigate the dependence of the fidelity of a Mach-Zehnder quantum
interferometer on the prior information about the phase, for Fock state input
and for maximally entangled (N00N) state input. For no prior information, the
fidelity for Fock state input is greater than for N00N state input. In the
limit of a narrow distribution describing the prior information, we find that
both Fock and N00N state inputs lead to nearly equal fidelity.
| [
{
"version": "v1",
"created": "Wed, 31 Jan 2007 18:47:17 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Bahder",
"Thomas B.",
""
],
[
"Lopata",
"Paul A.",
""
]
]
|
quant-ph/0701244 | Yong Zhang | Yong Zhang (1), Mo-Lin Ge (2) (1.Utah, 2. Chern Inst. Math.) | GHZ States, Almost-Complex Structure and Yang--Baxter Equation (I) | 17 pages, latex | Quant.Inf.Proc.6:363-379,2007 | null | null | quant-ph hep-th math-ph math.MP | null | Recent study suggests that there are natural connections between quantum
information theory and the Yang--Baxter equation. In this paper, in terms of
the generalized almost-complex structure and with the help of its algebra, we
define the generalized Bell matrix to yield all the GHZ states from the product
base, prove it to form a unitary braid representation and present a new type of
solution of the quantum Yang--Baxter equation. We also study
Yang-Baxterization, Hamiltonian, projectors, diagonalization, noncommutative
geometry, quantum algebra and FRT dual algebra associated with this generalized
Bell matrix.
| [
{
"version": "v1",
"created": "Wed, 31 Jan 2007 19:31:00 GMT"
}
]
| 2008-11-26T00:00:00 | [
[
"Zhang",
"Yong",
""
],
[
"Ge",
"Mo-Lin",
""
]
]
|
quant-ph/0701245 | Mark A. Rubin | Mark A. Rubin, Sumanth Kaushik | Signal-to-Noise Ratio in Squeezed-Light Laser Radar | Typos corrected | Appl. Opt. 48, 4597-4609 (2009) | 10.1364/AO.48.004597 | WW-13038 | quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The formalism for computing the signal-to-noise ratio (SNR) for laser radar
is reviewed and applied to the tasks of target detection, direction-finding,
and phase change estimation with squeezed light. The SNR for heterodyne
detection of coherent light using a squeezed local oscillator is lower than
that obtained using a coherent local oscillator. This is true for target
detection, for phase estimation, and for direction-finding with a split
detector. Squeezing the local oscillator also lowers SNR in balanced homodyne
and heterodyne detection of coherent light. Loss places an upper bound on the
improvement that squeezing can bring to direct-detection SNR.
| [
{
"version": "v1",
"created": "Wed, 31 Jan 2007 19:15:59 GMT"
},
{
"version": "v2",
"created": "Wed, 31 Jan 2007 21:01:33 GMT"
},
{
"version": "v3",
"created": "Sat, 25 Jul 2009 04:01:13 GMT"
},
{
"version": "v4",
"created": "Thu, 30 Jul 2009 17:53:42 GMT"
}
]
| 2009-08-12T00:00:00 | [
[
"Rubin",
"Mark A.",
""
],
[
"Kaushik",
"Sumanth",
""
]
]
|
quant-ph/0701246 | Tam\'as V\'ertesi | T. V\'ertesi | Genuine tripartite entanglement in the non-interacting Fermi gas | 9 pages, 4 figures, REVTeX | Phys. Rev. A 75, 042330 (2007) | 10.1103/PhysRevA.75.042330 | null | quant-ph | null | We study genuine tripartite entanglement shared among the spins of three
localized fermions in the non-interacting Fermi gas at zero temperature.
Firstly, we prove analytically with the aid of entanglement witnesses that in a
particular configuration the three fermions are genuinely tripartite entangled.
Then various three-fermion configurations are investigated in order to quantify
and calculate numerically the amount of genuine tripartite entanglement present
in the system. Further we give a lower and an upper limit to the maximum
diameter of the three-fermion configuration below which genuine tripartite
entanglement exists and find that this distance is comparable with the maximum
separation between two entangled fermions. The upper and lower limit turn to be
very close to each other indicating that the applied witness operator is well
suited to reveal genuine tripartite entanglement in the collection of
non-interacting fermions.
| [
{
"version": "v1",
"created": "Wed, 31 Jan 2007 20:53:35 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Vértesi",
"T.",
""
]
]
|
quant-ph/0702001 | Gerardo Adesso | Gerardo Adesso and Ivette Fuentes-Schuller | Correlation loss and multipartite entanglement across a black hole
horizon | 9 pages, 3 figures. Published version | Quant. Inf. Comput. 9, 0657-0665 (2009) | null | null | quant-ph astro-ph cond-mat.stat-mech gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the Hawking effect on entangled fields. By considering a
scalar field which is in a two-mode squeezed state from the point of view of
freely falling (Kruskal) observers crossing the horizon of a Schwarzschild
black hole, we study the degradation of quantum and classical correlations in
the state from the perspective of Schwarzschild observers confined outside the
horizon. Due to monogamy constraints on the entanglement distribution, we show
that the lost bipartite entanglement is recovered as multipartite entanglement
among modes inside and outside the horizon. In the limit of a small-mass black
hole, no bipartite entanglement is detected outside the horizon, while the
genuine multipartite entanglement interlinking the inner and outer regions
grows infinitely.
| [
{
"version": "v1",
"created": "Wed, 31 Jan 2007 21:01:44 GMT"
},
{
"version": "v2",
"created": "Tue, 26 Feb 2008 18:20:10 GMT"
},
{
"version": "v3",
"created": "Tue, 26 May 2009 17:10:50 GMT"
}
]
| 2009-05-26T00:00:00 | [
[
"Adesso",
"Gerardo",
""
],
[
"Fuentes-Schuller",
"Ivette",
""
]
]
|
quant-ph/0702002 | Alexander I. Lvovsky | Martin Oberst, Frank Vewinger, A. I. Lvovsky | Preparation and probing of the ground state coherence in Rubidium | null | Optics Letters 32, 1755 (2007) | 10.1364/OL.32.001755 | null | quant-ph | null | We demonstrate the preparation and probing of the coherence between the
hyperfine ground states |5S_{1/2}, F=1> and |5S_{1/2}, F=2> of the Rubidium 87
isotope. The effect of various coherence control techniques, i.e. fractional
Stimulated Raman Adiabatic Passage and Coherent Population Return on the
coherence are investigated. These techniques are implemented using nearly
degenerate pump and Stokes lasers at 795nm (Rubidium D1 transition) which
couple the two hyperfine ground states via the excited state |5P_{1/2}, F=1>
through a resonant two-photon process, in which a coherent superposition of the
two hyperfine ground states is established. The medium is probed by an
additional weak laser, which generates a four-wave mixing signal proportional
to the ground state coherence, and allows us to monitor its evolution in time.
The experimental data are compared with numerical simulations.
| [
{
"version": "v1",
"created": "Wed, 31 Jan 2007 22:10:46 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Oberst",
"Martin",
""
],
[
"Vewinger",
"Frank",
""
],
[
"Lvovsky",
"A. I.",
""
]
]
|
quant-ph/0702003 | Fernando Brandao | Fernando G.S.L. Brandao, Michael J. Hartmann, Martin B. Plenio | Quantum phase transitions with Photons and Polaritons | 7 pages, contribution for the proceedings of the QCMC06 | null | null | null | quant-ph | null | We show that a system of polaritons - combined atom and photon excitations -
in an array of coupled cavities, under an experimental set-up usually
considered in electromagnetically induced transparency, is described by the
Bose-Hubbard model. This opens up the possibility of using this system as a
quantum simulator, allowing for the observation of quantum phase transitions
and for the measurement of local properties, such as single site observables.
All the basic building blocks of the proposed setting have already been
achieved experimentally, showing the feasibility of its realization in the near
future.
| [
{
"version": "v1",
"created": "Wed, 31 Jan 2007 22:39:27 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Brandao",
"Fernando G. S. L.",
""
],
[
"Hartmann",
"Michael J.",
""
],
[
"Plenio",
"Martin B.",
""
]
]
|
quant-ph/0702004 | David Gross | David Gross | Non-negative Wigner functions in prime dimensions | 5 pages. Special case of a result proved in quant-ph/0602001. The
proof is greatly simplified, making the general case more accessible. To
appear in Appl. Phys. B as part of the proceedings of the 2006 DPG Spring
Meeting (Quantum Optics and Photonics section) | Appl. Phys. B 86, 367-370 (2007) | 10.1007/s00340-006-2510-9 | null | quant-ph | null | According to a classical result due to Hudson, the Wigner function of a pure,
continuous variable quantum state is non-negative if and only if the state is
Gaussian. We have proven an analogous statement for finite-dimensional quantum
systems. In this context, the role of Gaussian states is taken on by stabilizer
states. The general results have been published in [D. Gross, J. Math. Phys.
47, 122107 (2006)]. For the case of systems of odd prime dimension, a greatly
simplified proof can be employed which still exhibits the main ideas. The
present paper gives a self-contained account of these methods.
| [
{
"version": "v1",
"created": "Wed, 31 Jan 2007 22:53:22 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Gross",
"David",
""
]
]
|
quant-ph/0702005 | Jon Yard | Patrick Hayden, Michal Horodecki, Andreas Winter and Jon Yard | A decoupling approach to the quantum capacity | 13 pages, published version | Open Syst. Inf. Dyn. 15 (2008) 7-19 | 10.1142/S1230161208000043 | null | quant-ph cs.IT math.IT | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We give a short proof that the coherent information is an achievable rate for
the transmission of quantum information through a noisy quantum channel. Our
method is to produce random codes by performing a unitarily covariant
projective measurement on a typical subspace of a tensor power state. We show
that, provided the rank of each measurement operator is sufficiently small, the
transmitted data will with high probability be decoupled from the channel's
environment. We also show that our construction leads to random codes whose
average input is close to a product state and outline a modification yielding
unitarily invariant ensembles of maximally entangled codes.
| [
{
"version": "v1",
"created": "Thu, 1 Feb 2007 17:53:04 GMT"
},
{
"version": "v2",
"created": "Wed, 16 Nov 2016 05:29:48 GMT"
}
]
| 2016-11-17T00:00:00 | [
[
"Hayden",
"Patrick",
""
],
[
"Horodecki",
"Michal",
""
],
[
"Winter",
"Andreas",
""
],
[
"Yard",
"Jon",
""
]
]
|
quant-ph/0702006 | Michal Horodecki | Michal Horodecki, Seth Lloyd and Andreas Winter | Quantum coding theorem from privacy and distinguishability | Presented at the NATO ARW "Quantum Communication and Security", 10-13
September 2006, Gdansk, Poland; final version to appear in OSID special issue | Open Syst. Inf. Dyn. 15 (2008) 47-69 | null | null | quant-ph | null | We prove direct quantum coding theorem for random quantum codes. The problem
is separated into two parts: proof of distinguishability of codewords by
receiver, and that of indistinguishability of codewords by environment
(privacy). For a large class of codes, only privacy has to be checked.
| [
{
"version": "v1",
"created": "Wed, 31 Jan 2007 23:39:24 GMT"
},
{
"version": "v2",
"created": "Sat, 19 Jan 2008 00:05:37 GMT"
}
]
| 2008-04-03T00:00:00 | [
[
"Horodecki",
"Michal",
""
],
[
"Lloyd",
"Seth",
""
],
[
"Winter",
"Andreas",
""
]
]
|
quant-ph/0702007 | Jie-Hong Jiang | Jie-Hong R. Jiang (1), Dah-Wei Chiou (2), Cheng-En Wu (3) ((1)
Department of Electrical Engineering, National Taiwan University, Taiwan, (2)
Department of Physics, University of California, Berkeley, USA, (3)
Department of Physics, National Tsing Hua University, Taiwan) | Quantum Mechanical Search and Harmonic Perturbation | 6 pages, 4 figures, revtex4 | Quantum Information Processing 6(5), (Oct. 2007) 349-362 | 10.1007/s11128-007-0062-5 | null | quant-ph | null | Perturbation theory in quantum mechanics studies how quantum systems interact
with their environmental perturbations. Harmonic perturbation is a rare special
case of time-dependent perturbations in which exact analysis exists. Some
important technology advances, such as masers, lasers, nuclear magnetic
resonance, etc., originated from it. Here we add quantum computation to this
list with a theoretical demonstration. Based on harmonic perturbation, a
quantum mechanical algorithm is devised to search the ground state of a given
Hamiltonian. The intrinsic complexity of the algorithm is continuous and
parametric in both time T and energy E. More precisely, the probability of
locating a search target of a Hamiltonian in N-dimensional vector space is
shown to be 1/(1+ c N E^{-2} T^{-2}) for some constant c. This result is
optimal. As harmonic perturbation provides a different computation mechanism,
the algorithm may suggest new directions in realizing quantum computers.
| [
{
"version": "v1",
"created": "Thu, 1 Feb 2007 07:18:33 GMT"
},
{
"version": "v2",
"created": "Fri, 14 Sep 2007 15:50:08 GMT"
}
]
| 2008-01-01T00:00:00 | [
[
"Jiang",
"Jie-Hong R.",
""
],
[
"Chiou",
"Dah-Wei",
""
],
[
"Wu",
"Cheng-En",
""
]
]
|
quant-ph/0702008 | Dorit Aharonov | Dorit Aharonov, Itai Arad, Elad Eban, Zeph Landau | Polynomial Quantum Algorithms for Additive approximations of the Potts
model and other Points of the Tutte Plane | 82 pages. Up to page 36: the algorithm. From there on: The
universality proof. Most readers will want to read only the first part.
Presented at QIP 2007, Brisbane, Australia | null | null | null | quant-ph | null | In the first 36 pages of this paper, we provide polynomial quantum algorithms
for additive approximations of the Tutte polynomial, at any point in the Tutte
plane, for any planar graph. This includes as special cases the AJL algorithm
for the Jones polynomial, the partition function of the Potts model for any
weighted planer graph at any temperature, and many other combinatorial graph
properties. In the second part of the paper we prove the quantum universality
of many of the problems for which we provide an algorithm, thus providing a
large set of new quantum-complete problems. Unfortunately, we do not know that
this holds for the Potts model case; this is left as an important open problem.
The main progress in this work is in our ability to handle non-unitary
representations of the Temperley Lieb algebra, both when applying them in the
algorithm, and, more importantly, in the proof of universality, when encoding
quantum circuits using non-unitary operators. To this end we develop many new
tools, that allow proving density and applying the Solovay Kitaev theorem in
the case of non-unitary matrices. We hope that these tools will open up new
possibilities of using non-unitary reps in other quantum computation contexts.
| [
{
"version": "v1",
"created": "Thu, 1 Feb 2007 11:35:49 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Aharonov",
"Dorit",
""
],
[
"Arad",
"Itai",
""
],
[
"Eban",
"Elad",
""
],
[
"Landau",
"Zeph",
""
]
]
|
quant-ph/0702009 | Dorje C. Brody | Dorje C. Brody, Daniel W. Hook, and Lane P. Hughston | Unitarity, ergodicity, and quantum thermodynamics | 8 pages | J.Phys.A40:F503-F510,2007 | 10.1088/1751-8113/40/26/F01 | null | quant-ph hep-th | null | This paper is concerned with the ergodic subspaces of the state spaces of
isolated quantum systems. We prove a new ergodic theorem for closed quantum
systems which shows that the equilibrium state of the system takes the form of
a grand canonical density matrix involving a complete commuting set of
observables including the Hamiltonian. The result obtained, which is derived
for a generic finite-dimensional quantum system, shows that the equilibrium
state arising from unitary evolution is always expressible in the canonical
form, without the consideration of a system-bath decomposition.
| [
{
"version": "v1",
"created": "Thu, 1 Feb 2007 18:09:36 GMT"
},
{
"version": "v2",
"created": "Wed, 13 Jun 2007 10:43:11 GMT"
}
]
| 2008-11-26T00:00:00 | [
[
"Brody",
"Dorje C.",
""
],
[
"Hook",
"Daniel W.",
""
],
[
"Hughston",
"Lane P.",
""
]
]
|
quant-ph/0702010 | L. G. Suttorp | L.G. Suttorp | Field quantization in inhomogeneous anisotropic dielectrics with
spatio-temporal dispersion | 24 pages | Journal of Physics A 40 (2007)3697 | 10.1088/1751-8113/40/13/025 | ITFA-2007-08 | quant-ph | null | A quantum damped-polariton model is constructed for an inhomogeneous
anisotropic linear dielectric with arbitrary dispersion in space and time. The
model Hamiltonian is completely diagonalized by determining the creation and
annihilation operators for the fundamental polariton modes as specific linear
combinations of the basic dynamical variables. Explicit expressions are derived
for the time-dependent operators describing the electromagnetic field, the
dielectric polarization and the noise term in the latter. It is shown how to
identify bath variables that generate the dissipative dynamics of the medium.
| [
{
"version": "v1",
"created": "Thu, 1 Feb 2007 13:57:28 GMT"
},
{
"version": "v2",
"created": "Fri, 16 Feb 2007 14:10:55 GMT"
}
]
| 2018-08-16T00:00:00 | [
[
"Suttorp",
"L. G.",
""
]
]
|
quant-ph/0702011 | Angelo Bassi Dr. | A. Bassi, D.G.M. Salvetti | The quantum theory of measurement within dynamical reduction models | 24 pages, RevTeX. Minor changes made | J. Phys. A: Math. Theor. 40, 9859-9876 (2007). | 10.1088/1751-8113/40/32/011 | null | quant-ph | null | We analyze in mathematical detail, within the framework of the QMUPL model of
spontaneous wave function collapse, the von Neumann measurement scheme for the
measurement of a 1/2 spin particle. We prove that, according to the equation of
the model: i) throughout the whole measurement process, the pointer of the
measuring device is always perfectly well localized in space; ii) the
probabilities for the possible outcomes are distributed in agreement with the
Born probability rule; iii) at the end of the measurement the state of the
microscopic system has collapsed to the eigenstate corresponding to the
measured eigenvalue. This analysis shows rigorously how dynamical reduction
models provide a consistent solution to the measurement problem of quantum
mechanics.
| [
{
"version": "v1",
"created": "Thu, 1 Feb 2007 15:27:02 GMT"
},
{
"version": "v2",
"created": "Wed, 16 May 2007 21:38:06 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Bassi",
"A.",
""
],
[
"Salvetti",
"D. G. M.",
""
]
]
|
quant-ph/0702012 | C. A. Chatzidimitriou-Dreismann | C. Aris Chatzidimitriou-Dreismann | Attosecond neutron Compton scattering from protons | 9 pages, 1 figure, CEWQO-Conference, Vienna 2006 | Acta Phys. Hung. B 26/1-2, 203-212 (2006) | null | null | quant-ph | null | The effect of "anomalous" scattering of neutrons and electrons from protons
in the electron-volt energy-transfer range is considered, and related
experimental results are mentioned. A recent independent confirmation of this
effect with a new data analysis procedure is presented. Due to the very short
characteristic scattering time, there is no well defined separation of time
scales of electronic and protonic motions. An outline of a proposed theoretical
interpretation is presented, which is based on the fact that scattering protons
represent \textit{open} quantum systems, thus being subject to decoherence.
| [
{
"version": "v1",
"created": "Thu, 1 Feb 2007 15:43:00 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Chatzidimitriou-Dreismann",
"C. Aris",
""
]
]
|
quant-ph/0702013 | Gerardo Aquino | G. Aquino and B. Mehmani | Simultaneous Measurement of Non-Commuting Observables | 10 pages, 1 figure; Proceedings of the Workshop "Beyond the Quantum"
World Scientific (2007) | null | 10.1142/9789812771186_0009 | null | quant-ph | null | It is shown that the full unknown state of a spin-1/2 system, S, which,
within Born's statistical interpretation, is meant as the state of an ensamble
of identically prepared systems, can be determined with a simultaneous
measurement with the help of an "assistant" system A whose initial state is
known. The idea is to let S and A interact with each other in a known way
during a proper interaction time, to measure simultaneously two observables,
one of S and one of A and their correlation.
One thus determines the three unknown components of the polarization vector
of S by means of repeated experiments using a unique setting. In this way one
can measure simultaneously all the non-commutative observables of S, which
might seem prohibited in quantum mechanics.
| [
{
"version": "v1",
"created": "Thu, 1 Feb 2007 21:47:11 GMT"
}
]
| 2017-08-23T00:00:00 | [
[
"Aquino",
"G.",
""
],
[
"Mehmani",
"B.",
""
]
]
|
quant-ph/0702014 | Lorenza Viola | Lorenza Viola, Winton G. Brown | Generalized entanglement as a framework for complex quantum systems:
Purity vs delocalization measures | 17 pages, 3 figures | null | 10.1088/1751-8113/40/28/S17 | null | quant-ph | null | We establish contact between the delocalization properties of pure quantum
states, as quantified by their number of principal components, and the average
generalized entanglement properties, as quantified by purity measures relative
to different observable sets. We find that correlations between products of
state vector components with respect to Hamming distance play an important role
in the structure of subsystem-based purity measures. In particular, we derive
general conditions under which the amount of global multipartite entanglement
relates to the inverse participation ratio averaged over a maximal set of
mutually unbiased product bases. Furthermore, we provide a method for computing
the expected amount of generalized entanglement with respect to an arbitrary
observable set for random pure states. Specific examples and an explicit
application to a disordered quantum spin chain are discussed.
| [
{
"version": "v1",
"created": "Fri, 2 Feb 2007 01:55:28 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Viola",
"Lorenza",
""
],
[
"Brown",
"Winton G.",
""
]
]
|
quant-ph/0702015 | Hoshang Heydari | Hoshang Heydari | Topological quantum gate entangler for a multi-qubit state | 6 pages | J. Phys. A: Math. Theor. 40 (2007) 9877 - 9882 | 10.1088/1751-8113/40/32/012 | null | quant-ph | null | We establish a relation between topological and quantum entanglement for a
multi-qubit state by considering the unitary representations of the Artin braid
group. We construct topological operators that can entangle multi-qubit state.
In particular we construct operators that create quantum entanglement for
multi-qubit states based on the Segre ideal of complex multi-projective space.
We also in detail discuss and construct these operators for two-qubit and
three-qubit states.
| [
{
"version": "v1",
"created": "Fri, 2 Feb 2007 05:50:54 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Heydari",
"Hoshang",
""
]
]
|
quant-ph/0702016 | Dr. Georgios M. Nikolopoulos | V. Kost'ak, G. M. Nikolopoulos and I. Jex | Perfect state transfer in networks of arbitrary topology and coupling
configuration | 12 pages, 2 figures, to appear in Phys. Rev. A | Phys. Rev. A 75, 042319 (2007) | 10.1103/PhysRevA.75.042319 | null | quant-ph | null | A general formalism of the problem of perfect state transfer is presented. We
show that there are infinitely many Hamiltonians which may provide solution to
this problem. In a first attempt to give a classification of them we
investigate their possible forms and the related dynamics during the transfer.
Finally, we show how the present formalism can be used for the engineering of
perfect quantum wires of various topologies and coupling configurations.
| [
{
"version": "v1",
"created": "Fri, 2 Feb 2007 08:25:49 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Kost'ak",
"V.",
""
],
[
"Nikolopoulos",
"G. M.",
""
],
[
"Jex",
"I.",
""
]
]
|
quant-ph/0702017 | Kai Chen | Kai Chen, Sergio Albeverio and Shao-Ming Fei | Concurrence-based entanglement measure for Werner States | 5 pages, no figure | Rep. Math. Phys. 58, 325-334 (2006) | 10.1016/S0034-4877(07)00003-1 | null | quant-ph | null | We give explicit expressions for entanglement measures of Werner states in
arbitrary dimensions in terms of concurrence and tangle. We show that an
optimal ensemble decomposition for a joint density matrix of a Werner state can
achieve the minimum average concurrence and tangle simultaneously. Furthermore,
the same decomposition also attains entanglement of formation for Werner
states.
| [
{
"version": "v1",
"created": "Fri, 2 Feb 2007 10:15:52 GMT"
}
]
| 2012-10-30T00:00:00 | [
[
"Chen",
"Kai",
""
],
[
"Albeverio",
"Sergio",
""
],
[
"Fei",
"Shao-Ming",
""
]
]
|
quant-ph/0702018 | John H. Field | J. H. Field | On the Einstein-Podolsky-Rosen Proof of the `Incompleteness' of Quantum
Mechanics | 8 pages, v2 has typos corrected and small text additions. Version
submitted to Phys. Rev. A | null | null | null | quant-ph | null | It is shown that the Einstein-Podolsky-Rosen conclusion concerning the
`incompleteness' of Quantum Mechanics does not follow from the results of their
proposed gedanken experiment, but is rather stated as a premise. If it were
possible to perform the experiment it would, in fact, show that Quantum
Mechanics is `complete' for the observables discussed.
Because, however, of the non square-integrable nature of the wave function,
the proposed experiment gives vanishing probabilities for measurements
performed in finite intervals of configuration or momentum space. Hence no
conclusion as to the `completeness', or otherwise, of Quantum Mechanics can be
drawn from the experiment.
| [
{
"version": "v1",
"created": "Fri, 2 Feb 2007 10:54:07 GMT"
},
{
"version": "v2",
"created": "Fri, 7 Sep 2007 13:11:40 GMT"
}
]
| 2011-11-09T00:00:00 | [
[
"Field",
"J. H.",
""
]
]
|
quant-ph/0702019 | Toshio Ohshima | Toshio Ohshima, Artur Ekert, Daniel K. L. Oi, Dagomir Kaslizowski, L.
C. Kwek | Robust state transfer and rotation through a spin chain via dark passage | 4 pages, changed to simpler notations, typo corrected in version 2
typo corrected and minor changes in the discussion part made in version 3 | null | null | null | quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Quantum state transfer through a spin chain via adiabatic dark passage is
proposed. This technique is robust against control field fluctuations and
unwanted environmental coupling of intermediate spins. Our method can be
applied to spin chains with more than three spins. We also propose single qubit
rotation using this technique.
| [
{
"version": "v1",
"created": "Fri, 2 Feb 2007 13:03:31 GMT"
},
{
"version": "v2",
"created": "Mon, 12 Feb 2007 13:47:31 GMT"
},
{
"version": "v3",
"created": "Mon, 4 Aug 2008 14:41:03 GMT"
}
]
| 2008-08-04T00:00:00 | [
[
"Ohshima",
"Toshio",
""
],
[
"Ekert",
"Artur",
""
],
[
"Oi",
"Daniel K. L.",
""
],
[
"Kaslizowski",
"Dagomir",
""
],
[
"Kwek",
"L. C.",
""
]
]
|
quant-ph/0702020 | Janet Anders | Janet Anders, Damian Markham, Vlatko Vedral, Michal Hajdu\v{s}ek | How much of one-way computation is just thermodynamics? | 10 pages, 4 figures. Argument made clearer in line with referee
comments, this final version is 4 pages longer | Found. Phys. 38, 506 (2008) | 10.1007/s10701-008-9218-0 | null | quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper we argue that one-way quantum computation can be seen as a form
of phase transition with the available information about the solution of the
computation being the order parameter. We draw a number of striking analogies
between standard thermodynamical quantities such as energy, temperature, work,
and corresponding computational quantities such as the amount of entanglement,
time, potential capacity for computation, respectively. Aside from being
intuitively pleasing, this picture allows us to make novel conjectures, such as
an estimate of the necessary critical time to finish a computation and a
proposal of suitable architectures for universal one-way computation in 1D.
| [
{
"version": "v1",
"created": "Fri, 2 Feb 2007 15:57:45 GMT"
},
{
"version": "v2",
"created": "Fri, 20 Jun 2008 12:38:01 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Anders",
"Janet",
""
],
[
"Markham",
"Damian",
""
],
[
"Vedral",
"Vlatko",
""
],
[
"Hajdušek",
"Michal",
""
]
]
|
quant-ph/0702021 | Nicolas Gisin | Nicolas Gisin | Bell inequalities: many questions, a few answers | Contribution to a Festschrift dedicated to Abner Shimony. 8 pages
(May'07: minor corrections and additional references) | In essays in honour of Abner Shimony, Eds Wayne C. Myrvold and Joy
Christian, The Western Ontario Series in Philosophy of Science, pp 125-140,
Springer 2009 | null | null | quant-ph | null | What can be more fascinating than {\it experimental metaphysics}, to quote
one of Abner Shimony's enlightening expressions? Bell inequalities are at the
heart of the study of nonlocality. I present a list of open questions,
organised in three categories: fundamental; linked to experiments; and
exploring nonlocality as a resource. New families of inequalities for binary
outcomes are presented.
| [
{
"version": "v1",
"created": "Fri, 2 Feb 2007 17:53:53 GMT"
},
{
"version": "v2",
"created": "Sun, 13 May 2007 13:00:25 GMT"
}
]
| 2013-01-22T00:00:00 | [
[
"Gisin",
"Nicolas",
""
]
]
|
quant-ph/0702022 | Philippe Raynal | Philippe Raynal, Norbert L\"utkenhaus | Optimal unambiguous state discrimination of two density matrices: A
second class of exact solutions | final published version: 18 pages, 5 figures. to appear in PRA | Phys. Rev. A Vol 76, 052322 (2007) | 10.1103/PhysRevA.76.052322 | null | quant-ph | null | We consider the Unambiguous State Discrimination (USD) of two mixed quantum
states. We study the rank and the spectrum of the elements of an optimal USD
measurement. This naturally leads to a partial fourth reduction theorem. This
theorem shows that either the failure probability equals its overall lower
bound given in term of the fidelity or a two-dimensional subspace can be split
off from the original Hilbert space. We then use this partial reduction theorem
to derive the optimal solution for any two equally probable Geometrically
Uniform (GU) states $\rho_0$ and $\rho_1=U\rho_0 U^\dagger$, $U^2={\openone}$,
in a four-dimensional Hilbert space. This represents a second class of
analytical solutions for USD problems that cannot be reduced to some pure state
cases. We apply our result to answer two questions that are relevant in
implementations of the Bennett and Brassard 1984 quantum key distribution
protocol using weak coherent states.
| [
{
"version": "v1",
"created": "Fri, 2 Feb 2007 19:26:31 GMT"
},
{
"version": "v2",
"created": "Sat, 3 Nov 2007 16:32:00 GMT"
}
]
| 2007-12-11T00:00:00 | [
[
"Raynal",
"Philippe",
""
],
[
"Lütkenhaus",
"Norbert",
""
]
]
|
quant-ph/0702023 | Christian de Ronde | Graciela Domenech and Hector Freytes | Contextual logic for quantum systems | 16 pages, no figures | J. Math. Phys. 46 (2005) 012102 | 10.1063/1.1819525 | null | quant-ph | null | In this work we build a quantum logic that allows us to refer to physical
magnitudes pertaining to different contexts from a fixed one without the
contradictions with quantum mechanics expressed in no-go theorems. This logic
arises from considering a sheaf over a topological space associated to the
Boolean sublattices of the ortholattice of closed subspaces of the Hilbert
space of the physical system. Differently to standard quantum logics, the
contextual logic maintains a distributive lattice structure and a good
definition of implication as a residue of the conjunction.
| [
{
"version": "v1",
"created": "Fri, 2 Feb 2007 20:13:42 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Domenech",
"Graciela",
""
],
[
"Freytes",
"Hector",
""
]
]
|
quant-ph/0702024 | Bryan J. Dalton | B J Dalton | Theory of decoherence in Bose-Einstein condensate interferometry | Proceedings DICE 06 Conference, 11-15 Sept 2006, Piombino, Italy | J. Phys. Conf. Series 67, 012059 (2007) | 10.1088/1742-6596/67/1/012059 | null | quant-ph | null | A full treatment of decoherence and dephasing effects in BEC interferometry
has been developed based on using quantum correlation functions for treating
interferometric effects. The BEC is described via a phase space distribution
functional of the Wigner type for the condensate modes and the positive P type
for the non-condensate modes. Ito equations for stochastic condensate and
non-condensate field functions replace the functional Fokker-Planck equation
for the distribution functional and stochastic averages of field function
products determine the quantum correlation functions.
| [
{
"version": "v1",
"created": "Sat, 3 Feb 2007 02:03:52 GMT"
}
]
| 2015-06-26T00:00:00 | [
[
"Dalton",
"B J",
""
]
]
|
quant-ph/0702025 | Olivier Brunet | Olivier Brunet (Leibniz - IMAG) | An Intrisic Topology for Orthomodular Lattices | Under submission to the International Journal of Theoretical Physics | null | 10.1007/s10773-007-9400-8 | null | quant-ph math-ph math.GN math.LO math.MP | null | We present a general way to define a topology on orthomodular lattices. We
show that in the case of a Hilbert lattice, this topology is equivalent to that
induced by the metrics of the corresponding Hilbert space. Moreover, we show
that in the case of a boolean algebra, the obtained topology is the discrete
one. Thus, our construction provides a general tool for studying orthomodular
lattices but also a way to distinguish classical and quantum logics.
| [
{
"version": "v1",
"created": "Sat, 3 Feb 2007 07:23:23 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Brunet",
"Olivier",
"",
"Leibniz - IMAG"
]
]
|
quant-ph/0702026 | Adam Miranowicz | A. Miranowicz, S. K. Ozdemir, Yu-xi Liu, G. Chimczak, M. Koashi, N.
Imoto | Quantum Entanglement and Teleportation of Quantum-Dot States in
Microcavities | 9 pages, 7 figures, to appear in e-J. Surf. Sci. Nanotech | e-J. Surf. Sci. Nanotech. 5, 51-59 (2007). | 10.1380/ejssnt.2007.51 | null | quant-ph | null | Generation and control of quantum entanglement are studied in an
equivalent-neighbor system of spatially-separated semiconductor quantum dots
coupled by a single-mode cavity field. Generation of genuinely multipartite
entanglement of qubit states realized by conduction-band electron-spin states
in quantum dots is discussed. A protocol for quantum teleportation of
electron-spin states via cavity decay is briefly described.
| [
{
"version": "v1",
"created": "Sat, 3 Feb 2007 15:37:20 GMT"
}
]
| 2009-08-04T00:00:00 | [
[
"Miranowicz",
"A.",
""
],
[
"Ozdemir",
"S. K.",
""
],
[
"Liu",
"Yu-xi",
""
],
[
"Chimczak",
"G.",
""
],
[
"Koashi",
"M.",
""
],
[
"Imoto",
"N.",
""
]
]
|
quant-ph/0702027 | H. Dong | H. Dong, S. Yang, X.F. Liu, C.P. Sun | Quantum Thermalization With Couplings | 4 pages, 2 figures | Phys. Rev. A 76, 044104 (2007) | 10.1103/PhysRevA.76.044104 | null | quant-ph cond-mat.stat-mech | null | We study the role of the system-bath coupling for the generalized canonical
thermalization [S. Popescu, et al., Nature Physics 2,754(2006) and S. Goldstein
et al., Phys. Rev. Lett. 96, 050403(2006)] that reduces almost all the pure
states of the "universe" [formed by a system S plus its surrounding heat bath
$B$] to a canonical equilibrium state of S. We present an exactly solvable, but
universal model for this kinematic thermalization with an explicit
consideration about the energy shell deformation due to the interaction between
S and B. By calculating the state numbers of the "universe" and its subsystems
S and B in various deformed energy shells, it is found that, for the
overwhelming majority of the "universe" states (they are entangled at least),
the diagonal canonical typicality remains robust with respect to finite
interactions between S and B. Particularly, the kinematic decoherence is
utilized here to account for the vanishing of the off-diagonal elements of the
reduced density matrix of S. It is pointed out that the non-vanishing
off-diagonal elements due to the finiteness of bath and the stronger
system-bath interaction might offer more novelties of the quantum
thermalization.
| [
{
"version": "v1",
"created": "Sun, 4 Feb 2007 12:46:26 GMT"
},
{
"version": "v2",
"created": "Wed, 28 Mar 2007 09:59:36 GMT"
}
]
| 2011-11-09T00:00:00 | [
[
"Dong",
"H.",
""
],
[
"Yang",
"S.",
""
],
[
"Liu",
"X. F.",
""
],
[
"Sun",
"C. P.",
""
]
]
|
quant-ph/0702028 | Hongbao Zhang | Song He, Shuxin Shao, and Hongbao Zhang | Entanglement Entropy: Helicity versus Spin | 3 pages, title changed, typos corrected, version to appear in Int. J.
Quant. Inf | Int.J.Quant.Inf.6:181,2008 | 10.1142/S0219749908003360 | null | quant-ph hep-th | null | For a massive spin 1/2 field, we present the reduced spin and helicity
density matrix, respectively, for the same pure one particle state. Their
relation has also been developed. Furthermore, we calculate and compare the
corresponding entanglement entropy for spin and helicity within the same
inertial reference frame. Due to the distinct dependence on momentum degree of
freedom between spin and helicity states, the resultant helicity entropy is
different from that of spin in general. In particular, we find that both
helicity entanglement for a spin eigenstate and spin entanglement for a right
handed or left handed helicity state do not vanish and their Von Neumann
entropy has no dependence on the specific form of momentum distribution as long
as it is isotropic.
| [
{
"version": "v1",
"created": "Mon, 5 Feb 2007 15:28:52 GMT"
},
{
"version": "v2",
"created": "Tue, 25 Dec 2007 01:48:42 GMT"
}
]
| 2008-11-26T00:00:00 | [
[
"He",
"Song",
""
],
[
"Shao",
"Shuxin",
""
],
[
"Zhang",
"Hongbao",
""
]
]
|
quant-ph/0702029 | Kurt Jacobs | Kosuke Shizume, Kurt Jacobs, Daniel Burgarth, Sougato Bose | Quantum communication via a continuously monitored dual spin chain | 5 pages, revtex 4, 3 eps figures | Phys. Rev. A 75, 062328 (2007) | 10.1103/PhysRevA.75.062328 | null | quant-ph | null | We analyze a recent protocol for the transmission of quantum states via a
dual spin chain [Burgarth and Bose, Phys. Rev. A 71, 052315 (2005)] under the
constraint that the receiver's measurement strength is finite. That is, we
consider the channel where the ideal, instantaneous and complete von Neumann
measurements are replaced with a more realistic continuous measurement. We show
that for optimal performance the measurement strength must be "tuned" to the
channel spin-spin coupling, and once this is done, one is able to achieve a
similar transmission rate to that obtained with ideal measurements. The spin
chain protocol thus remains effective under measurement constraints.
| [
{
"version": "v1",
"created": "Sun, 4 Feb 2007 16:29:28 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Shizume",
"Kosuke",
""
],
[
"Jacobs",
"Kurt",
""
],
[
"Burgarth",
"Daniel",
""
],
[
"Bose",
"Sougato",
""
]
]
|
quant-ph/0702030 | Feng Pan | Feng Pan, Xin Guan, Nan Ma, Wen-Juan Han, and J. P. Draayer | Exact diagonalization for spin-1/2 chains and the first order quantum
phase transitions of the XXX chain in a uniform transverse field | 7pages LaTeX, 1figure | null | 10.1088/0953-8984/19/38/386208 | 0704-LNNU-LSU | quant-ph cond-mat.str-el | null | A simple Mathematica code based on the differential realization of hard-core
boson operators for finding exact solutions of the periodic-N spin-1/2 systems
with or beyond nearest neighbor interactions is proposed, which can easily be
used to study general spin-1/2 interaction systems. As an example, The code is
applied to study XXX spin-1/2 chain with nearest neighbor interaction in a
uniform transverse field. It shows that there are [N/2] level-crossing points
in the ground state, where N is the periodic number of the system and [x]
stands for the integer part of x, when the interaction strength and magnitude
of the magnetic field satisfy certain conditions. The quantum phase
transitional behavior in the ground state of the system in the thermodynamic
limit is also studied.
| [
{
"version": "v1",
"created": "Sun, 4 Feb 2007 19:47:04 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Pan",
"Feng",
""
],
[
"Guan",
"Xin",
""
],
[
"Ma",
"Nan",
""
],
[
"Han",
"Wen-Juan",
""
],
[
"Draayer",
"J. P.",
""
]
]
|
quant-ph/0702031 | L. M. Duan | Y.-J. Han, R. Raussendorf, and L.-M. Duan | A scheme for demonstration of fractional statistics of anyons in an
exactly solvable model | 4 pages, 3 figures | Phys. Rev. Lett. 98, 150404 (2007). | 10.1103/PhysRevLett.98.150404 | null | quant-ph cond-mat.other | null | We propose a scheme to demonstrate fractional statistics of anyons in an
exactly solvable lattice model proposed by Kitaev that involves four-body
interactions. The required many-body ground state, as well as the anyon
excitations and their braiding operations, can be conveniently realized through
\textit{dynamic}laser manipulation of cold atoms in an optical lattice. Due to
the perfect localization of anyons in this model, we show that a quantum
circuit with only six qubits is enough for demonstration of the basic braiding
statistics of anyons. This opens up the immediate possibility of
proof-of-principle experiments with trapped ions, photons, or nuclear magnetic
resonance systems.
| [
{
"version": "v1",
"created": "Mon, 5 Feb 2007 01:37:03 GMT"
}
]
| 2013-05-29T00:00:00 | [
[
"Han",
"Y. -J.",
""
],
[
"Raussendorf",
"R.",
""
],
[
"Duan",
"L. -M.",
""
]
]
|
quant-ph/0702032 | Sahel Ashhab | S. Ashhab, J. R. Johansson, A. M. Zagoskin, Franco Nori | Two-level systems driven by large-amplitude fields | 10 pages (two-column), 6 figures | Phys. Rev. A 75, 063414 (2007) | 10.1103/PhysRevA.75.063414 | null | quant-ph cond-mat.other cond-mat.supr-con | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We analyze the dynamics of a two-level system subject to driving by
large-amplitude external fields, focusing on the resonance properties in the
case of driving around the region of avoided level crossing. In particular, we
consider three main questions that characterize resonance dynamics: (1) the
resonance condition, (2) the frequency of the resulting oscillations on
resonance and (3) the width of the resonance. We identify the regions of
validity of different approximations. In a large region of the parameter space,
we use a geometric picture in order to obtain both a simple understanding of
the dynamics and quantitative results. The geometric approach is obtained by
dividing the evolution into discrete time steps, with each time step described
by either a phase shift on the basis states or a coherent mixing process
corresponding to a Landau-Zener crossing. We compare the results of the
geometric picture with those of a rotating-wave approximation. We also comment
briefly on the prospects of employing strong driving as a useful tool to
manipulate two-level systems.
| [
{
"version": "v1",
"created": "Mon, 5 Feb 2007 07:47:06 GMT"
},
{
"version": "v2",
"created": "Wed, 20 Jun 2007 08:08:20 GMT"
},
{
"version": "v3",
"created": "Fri, 17 Jul 2009 10:57:13 GMT"
}
]
| 2009-07-17T00:00:00 | [
[
"Ashhab",
"S.",
""
],
[
"Johansson",
"J. R.",
""
],
[
"Zagoskin",
"A. M.",
""
],
[
"Nori",
"Franco",
""
]
]
|
quant-ph/0702033 | Massimiliano Federico Sacchi | Massimiliano F. Sacchi | Information-disturbance tradeoff in covariant quantum state estimation | 4 pages; contribution for the proceedings of the QCMC06 | In Proceedings of the 8th Int. Conf. on Quantum Communication,
Measurement and Computing, ed. by O. Hirota, J. H. Shapiro and M. Sasaki
(NICT press, Japan, 2007), p. 331 | null | null | quant-ph | null | We provide a general framework for quantifying the optimal tradeoff between
the information retrieved by a quantum measurement and the disturbance on the
quantum state in covariant quantum state estimation.
| [
{
"version": "v1",
"created": "Mon, 5 Feb 2007 10:52:18 GMT"
}
]
| 2007-08-29T00:00:00 | [
[
"Sacchi",
"Massimiliano F.",
""
]
]
|
quant-ph/0702034 | Markus Hijlkema | Markus Hijlkema, Bernhard Weber, Holger P. Specht, Simon C. Webster,
Axel Kuhn and Gerhard Rempe | A Single-Photon Server with Just One Atom | 4 pages, 3 figures | null | null | null | quant-ph | null | Neutral atoms are ideal objects for the deterministic processing of quantum
information. Entanglement operations have been performed by photon exchange or
controlled collisions. Atom-photon interfaces were realized with single atoms
in free space or strongly coupled to an optical cavity. A long standing
challenge with neutral atoms, however, is to overcome the limited observation
time. Without exception, quantum effects appeared only after ensemble
averaging. Here we report on a single-photon source with one-and-only-one atom
quasi permanently coupled to a high-finesse cavity. Quasi permanent refers to
our ability to keep the atom long enough to, first, quantify the
photon-emission statistics and, second, guarantee the subsequent performance as
a single-photon server delivering up to 300,000 photons for up to 30 seconds.
This is achieved by a unique combination of single-photon generation and atom
cooling. Our scheme brings truly deterministic protocols of quantum information
science with light and matter within reach.
| [
{
"version": "v1",
"created": "Mon, 5 Feb 2007 13:20:41 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Hijlkema",
"Markus",
""
],
[
"Weber",
"Bernhard",
""
],
[
"Specht",
"Holger P.",
""
],
[
"Webster",
"Simon C.",
""
],
[
"Kuhn",
"Axel",
""
],
[
"Rempe",
"Gerhard",
""
]
]
|
quant-ph/0702035 | Durga Bhaktavatsala Rao | D. D. Bhaktavatsala Rao, V. Ravishankar and V. Subrahmanyam | Decoherence of two-electron spin states in quantum dots | 12 pages, 6 figures. submitted to Phys. Rev. A | Phys. Rev. A 75, 052338 (2007) | 10.1103/PhysRevA.75.052338 | null | quant-ph cond-mat.mes-hall | null | The time evolution of spin states of two electrons interacting with a nuclear
spin bath in a quantum dot system is studied. The hyperfine interaction between
the electrons and the nuclear spins is modeled by an isotropic Heisenberg
interaction, and the interaction between the electron spins by Heisenberg
exchange. Depending on the extent of the overlap between the spatial wave
functions of the electrons, there are two physically different cases, namely
the two qubits either interact with the same set of nuclear spins or they see
different nuclear spin environment. In the two cases, the decoherence of the
two-qubit state is studied analytically. We have identified a class of
two-qubit states which have a rich dynamics when the exchange interaction
between the qubits becomes large in comparison to the hyperfine interaction
strengths. The decoherence time scale is determined as a function of the
bath-spin distribution and the polarizations of the initial two-qubit state.
States with large decoherence times are identified by performing a minimization
over all the two-qubit pure states.
| [
{
"version": "v1",
"created": "Mon, 5 Feb 2007 12:49:28 GMT"
}
]
| 2013-07-09T00:00:00 | [
[
"Rao",
"D. D. Bhaktavatsala",
""
],
[
"Ravishankar",
"V.",
""
],
[
"Subrahmanyam",
"V.",
""
]
]
|
quant-ph/0702036 | Laleh Memarzadeh | S. Alipour, V. Karimipour, L. Memarzadeh | Entanglement and quantum phase transitions in matrix product spin one
chains | null | Phys. Rev. A 75, 052322 (2007) | 10.1103/PhysRevA.75.052322 | null | quant-ph | null | We consider a one-parameter family of matrix product states of spin one
particles on a periodic chain and study in detail the entanglement properties
of such a state. In particular we calculate exactly the entanglement of one
site with the rest of the chain, and the entanglement of two distant sites with
each other and show that the derivative of both these properties diverge when
the parameter $g$ of the states passes through a critical point. Such a point
can be called a point of quantum phase transition, since at this point, the
character of the matrix product state which is the ground state of a
Hamiltonian, changes discontinuously. We also study the finite size effects and
show how the entanglement depends on the size of the chain. This later part is
relevant to the field of quantum computation where the problem of initial state
preparation in finite arrays of qubits or qutrits is important. It is also
shown that entanglement of two sites have scaling behavior near the critical
point.
| [
{
"version": "v1",
"created": "Mon, 5 Feb 2007 13:10:25 GMT"
},
{
"version": "v2",
"created": "Wed, 14 Feb 2007 08:15:16 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Alipour",
"S.",
""
],
[
"Karimipour",
"V.",
""
],
[
"Memarzadeh",
"L.",
""
]
]
|
quant-ph/0702037 | Adnan Tegmen | A. Tegmen, T. Altanhan and B. S. Kandemir | Two-particle Wigner functions in a one-dimensional Calogero-Sutherland
potential | 14 pages, 4 figures, The original publication is available at
www.eurphysj.org | Eur Phys J D41 (2007) 397-402 | 10.1140/epjd/e2006-00221-1 | null | quant-ph | null | We calculate the Wigner distribution function for the Calogero-Sutherland
system which consists of harmonic and inverse-square interactions. The Wigner
distribution function is separated out into two parts corresponding to the
relative and center-of-mass motions. A general expression for the relative
Wigner function is obtained in terms of the Laguerre polynomials by introducing
a new identity between Hermite and Laguerre polynomials.
| [
{
"version": "v1",
"created": "Mon, 5 Feb 2007 14:38:01 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Tegmen",
"A.",
""
],
[
"Altanhan",
"T.",
""
],
[
"Kandemir",
"B. S.",
""
]
]
|
quant-ph/0702038 | C. A. Chatzidimitriou-Dreismann | C. Aris Chatzidimitriou-Dreismann and Stig Stenholm | On correlation approach to scattering in the decoherence timescale -
Towards the theoretical interpretation of NCS and ECS experimental findings | Published in: "Decoherence, Entanglement and Information Protection
in Complex Quantum Systems", NATO Science Series II - Vol.189, eds V. M.
Akulin, A. Sarfati, G. Kurizki and S. Pellegrin (Springer, Dordrecht, 2005)
pp. 555-562 | V. M. Akulin et al. (eds.), NATO Science Series II - Vol. 189, pp.
555-562 (Springer, Dordrecht, 2005) | null | null | quant-ph | null | We provide a "first principles" description of scattering from open quantum
systems subject to a Lindblad-type dynamics. In particular we consider the case
that the duration of the scattering process is of similar order as the
decoherence time of the scatterer. Under rather general conditions, the
derivations lead to the the following new result: The irreversible
time-evolution may cause a reduction of the system's transition rate being
effectuated by scattering. This is tantamount to a shortfall of scattering
intensity. The possible connection with striking experimental results of
neutron and electron Compton scattering from protons in condensed matter is
mentioned.
| [
{
"version": "v1",
"created": "Mon, 5 Feb 2007 14:44:00 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Chatzidimitriou-Dreismann",
"C. Aris",
""
],
[
"Stenholm",
"Stig",
""
]
]
|
quant-ph/0702039 | Patricia Lee | P. J. Lee, M. Anderlini, B. L. Brown, J. Sebby-Strabley, W. D.
Phillips, J. V. Porto | Sublattice addressing and spin-dependent motion of atoms in a
double-well lattice | null | Physical Review Letters 99, 020402 (2007) | 10.1103/PhysRevLett.99.020402 | null | quant-ph | null | We load atoms into every site of an optical lattice and selectively spin flip
atoms in a sublattice consisting of every other site. These selected atoms are
separated from their unselected neighbors by less than an optical wavelength.
We also show spin-dependent transport, where atomic wave packets are coherently
separated into adjacent sites according to their internal state. These tools
should be useful for quantum information processing and quantum simulation of
lattice models with neutral atoms.
| [
{
"version": "v1",
"created": "Mon, 5 Feb 2007 16:58:49 GMT"
},
{
"version": "v2",
"created": "Tue, 17 Apr 2007 18:35:56 GMT"
}
]
| 2007-08-15T00:00:00 | [
[
"Lee",
"P. J.",
""
],
[
"Anderlini",
"M.",
""
],
[
"Brown",
"B. L.",
""
],
[
"Sebby-Strabley",
"J.",
""
],
[
"Phillips",
"W. D.",
""
],
[
"Porto",
"J. V.",
""
]
]
|
quant-ph/0702040 | Roland Hildebrand | Roland Hildebrand | Entangled states close to the maximally mixed state | 11 pages; v2: n qubit case added | null | 10.1103/PhysRevA.75.062330 | null | quant-ph | null | We give improved upper bounds on the radius of the largest ball of separable
states of an m-qubit system around the maximally mixed state. The ratio between
the upper bound and the best known lower bound (Hildebrand, quant.ph/0601201)
thus shrinks to a constant c = \sqrt{34/27} ~ 1.122, as opposed to a term of
order \sqrt{m\log m} for the best upper bound known previously (Aubrun and
Szarek, quant.ph/0503221). We give concrete examples of separable states on the
boundary to entanglement which realize these upper bounds. As a by-product, we
compute the radii of the largest balls that fit into the projective tensor
product of four unit balls in R^3 and in the projective tensor product of an
arbitrary number of unit balls in R^n for n = 2,4,8.
| [
{
"version": "v1",
"created": "Mon, 5 Feb 2007 17:36:51 GMT"
},
{
"version": "v2",
"created": "Fri, 23 Feb 2007 14:36:54 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Hildebrand",
"Roland",
""
]
]
|
quant-ph/0702041 | Joshua Nunn | J. Nunn, I. A. Walmsley, M. G. Raymer, K. Surmacz, F. C. Waldermann,
Z. Wang, D. Jaksch | Mapping broadband single-photon wavepackets into an atomic memory | 5 pages, 4 figures, published in PRA Rapid Communications | Phys. Rev. A 75, 011401(R) (2007) | 10.1103/PhysRevA.75.011401 | null | quant-ph | null | We analyze a quantum optical memory based on the off-resonant Raman
interaction of a single broadband photon, copropagating with a classical
control pulse, with an atomic ensemble. The conditions under which the memory
can perform optimally are found, by means of a `universal' mode decomposition.
This enables the memory efficiency to be specified in terms of a single
parameter, and the control field pulse shape to be determined via a simple
nonlinear scaling. We apply the same decomposition to determine the optimal
configurations for read-out.
| [
{
"version": "v1",
"created": "Mon, 5 Feb 2007 18:27:15 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Nunn",
"J.",
""
],
[
"Walmsley",
"I. A.",
""
],
[
"Raymer",
"M. G.",
""
],
[
"Surmacz",
"K.",
""
],
[
"Waldermann",
"F. C.",
""
],
[
"Wang",
"Z.",
""
],
[
"Jaksch",
"D.",
""
]
]
|
quant-ph/0702042 | Francisco R Villatoro | Francisco R. Villatoro and Juan A. Monsoriu | Tunnelling in quantum superlattices with variable lacunarity | 12 pages, 3 figures | Physics Letters A 372 (2008) 3801-3807 | 10.1016/j.physleta.2008.03.002 | null | quant-ph | null | Quantum fractal superlattices are microelectronic devices consisting of a
series of thin layers of two semiconductor materials deposited alternately on
each other over a substrate following the rules of construction of a fractal
set, here, a symmetrical polyadic Cantor fractal. The scattering properties of
electrons in these superlattices may be modeled by using that of quantum
particles in piecewise constant potential wells. The twist plots representing
the reflection coefficient as function of the lacunarity parameter show the
appearance of black curves with perfectly transparent tunnelling which may be
classified as vertical, arc, and striation nulls. Approximate analytical
formulae for these reflection-less curves are derived using the transfer matrix
method. Comparison with the numerical results show their good accuracy.
| [
{
"version": "v1",
"created": "Mon, 5 Feb 2007 19:47:42 GMT"
},
{
"version": "v2",
"created": "Thu, 8 Feb 2007 17:51:13 GMT"
}
]
| 2012-08-21T00:00:00 | [
[
"Villatoro",
"Francisco R.",
""
],
[
"Monsoriu",
"Juan A.",
""
]
]
|
quant-ph/0702043 | Constantin V. Usenko | Constantin V. Usenko | Production of Information and Entropy in measurement of entangled states | Presented at the NATO ARW "Quantum Communication and Security", 10-13
September 2006, Gdansk, Poland | null | null | null | quant-ph | null | Problem of classification of all the set of entangled states is considered.
Invariance of entangled states relative to transformations from a group of
symmetry of qubit space leads to classification of all states of the system
through irreducible representations from that group.
Excess of entropy of a subsystem over entropy of the whole system indicates
the presence of entaglement in the system.
| [
{
"version": "v1",
"created": "Mon, 5 Feb 2007 20:17:13 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Usenko",
"Constantin V.",
""
]
]
|
quant-ph/0702044 | Daniel E. Browne | M. Varnava, D.E. Browne and T. Rudolph | How good must single photon sources and detectors be for efficient
linear optical quantum computation? | New version contains an Added Appendix | Phys. Rev. Lett. 100, 060502 (2008). | 10.1103/PhysRevLett.100.060502 | null | quant-ph | null | We present a scheme for linear optical quantum computation (LOQC) which is
highly robust to imperfect single photon sources and inefficient detectors. In
particular we show that if the product of the detector efficiency with the
source efficiency is greater than 2/3, then efficient LOQC is possible. This
threshold is many orders of magnitude more relaxed than those which could be
inferred by application of standard results in fault tolerance. The result is
achieved within the cluster state paradigm for quantum computation.
| [
{
"version": "v1",
"created": "Mon, 5 Feb 2007 20:47:53 GMT"
},
{
"version": "v2",
"created": "Fri, 20 Jul 2007 15:20:01 GMT"
}
]
| 2009-09-29T00:00:00 | [
[
"Varnava",
"M.",
""
],
[
"Browne",
"D. E.",
""
],
[
"Rudolph",
"T.",
""
]
]
|
quant-ph/0702045 | Jun Zhang | Jun Zhang, Xiao-Hui Bao, Teng-Yun Chen, Tao Yang, Adan Cabello, and
Jian-Wei Pan | Experimental quantum "Guess my Number" protocol using multiphoton
entanglement | 4 pages, 2 figures | Phys. Rev. A 75, 022302 (2007) | 10.1103/PhysRevA.75.022302 | null | quant-ph | null | We present an experimental demonstration of a modified version of the
entanglement-assisted "Guess my Number" protocol for the reduction of
communication complexity among three separated parties. The results of
experimental measurements imply that the separated parties can compute a
function of distributed inputs by exchanging less classical information than by
using any classical strategy. And the results also demonstrate the advantages
of entanglement-enhanced communication, which is very close to quantum
communication. The advantages are based on the properties of
Greenberger-Horne-Zeilinger states.
| [
{
"version": "v1",
"created": "Tue, 6 Feb 2007 00:25:46 GMT"
}
]
| 2008-08-22T00:00:00 | [
[
"Zhang",
"Jun",
""
],
[
"Bao",
"Xiao-Hui",
""
],
[
"Chen",
"Teng-Yun",
""
],
[
"Yang",
"Tao",
""
],
[
"Cabello",
"Adan",
""
],
[
"Pan",
"Jian-Wei",
""
]
]
|
quant-ph/0702046 | Xinwei Zha | Xin-wei Zha, Chun-min Zhang | LU transformation invariant operators and LU transformation invariant | 6 pages, no figures | null | null | null | quant-ph | null | We proposed a concept of LU transformation invariant operators. By using this
operator, arbitrary multi-qubit states LU transformation invariant and SLOCC
invariant could be easily obtained. And we find that presences two kinds of
invariant operators and corresponding invariants. One kind of operators yields
LU invariants and the other operators results in SLOCC invariants. For
three-qubit states, all independence LU transformation invariant are obtained.
Furthermore, by this system method, arbitrary multi-qubit states invariants can
be given.
| [
{
"version": "v1",
"created": "Tue, 6 Feb 2007 00:36:19 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Zha",
"Xin-wei",
""
],
[
"Zhang",
"Chun-min",
""
]
]
|
quant-ph/0702047 | Mark S. Byrd | Lian-Ao Wu and Mark S. Byrd | Self-Protected Quantum Algorithms Based on Quantum State Tomography | 6 pages, no figures | Quantum Information Processing, Vol. 8, 1 (2009) | null | null | quant-ph | null | Only a few classes of quantum algorithms are known which provide a speed-up
over classical algorithms. However, these and any new quantum algorithms
provide important motivation for the development of quantum computers. In this
article new quantum algorithms are given which are based on quantum state
tomography. These include an algorithm for the calculation of several quantum
mechanical expectation values and an algorithm for the determination of
polynomial factors. These quantum algorithms are important in their own right.
However, it is remarkable that these quantum algorithms are immune to a large
class of errors. We describe these algorithms and provide conditions for
immunity.
| [
{
"version": "v1",
"created": "Tue, 6 Feb 2007 01:03:11 GMT"
}
]
| 2009-02-04T00:00:00 | [
[
"Wu",
"Lian-Ao",
""
],
[
"Byrd",
"Mark S.",
""
]
]
|
quant-ph/0702048 | Vyacheslav Gorshkov Mr | G.P. Berman (Theoretical Division, Los Alamos National Laboratory, Los
Alamos, USA), V.N. Gorshkov (Theoretical Division, Los Alamos National
Laboratory; Institute of Physics, National Academy of Sciences, Kiev,
Ukraine), and V.I.Tsifrinovich (Physics Department, Polytechnic University,
Brooklyn, New York) | Quantum Annealing for Heisenberg Spin Chains | 10 pages, 13 figures | null | null | null | quant-ph | null | We suggest using the method of quantum annealing for computing the ground
state of the Heisenberg spin chains. Our initial Hamiltonian describes a spin
system in a highly non-uniform magnetic field. The initial Hamiltonian
gradually transforms into the Heisenberg Hamiltonian, which describes the
exchange interaction and the Zeeman interaction with the uniform magnetic
field. We demonstrate quantum annealing for 2-, 3-, and 9-spin systems. In
particular, we consider the alternate (ferro- and antiferromagnetic) exchange
integral. By changing the sign of the exchange integrals we switch from the
frustrated to the corresponding non-frustrated spin system. We discuss the
similarity and difference between the frustrated and non-frustrated spin
systems.
| [
{
"version": "v1",
"created": "Tue, 6 Feb 2007 06:00:03 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Berman",
"G. P.",
"",
"Theoretical Division, Los Alamos National Laboratory, Los\n Alamos, USA"
],
[
"Gorshkov",
"V. N.",
"",
"Theoretical Division, Los Alamos National\n Laboratory; Institute of Physics, National Academy of Sciences, Kiev,\n Ukraine"
],
[
"Tsifrinovich",
"V. I.",
"",
"Physics Department, Polytechnic University,\n Brooklyn, New York"
]
]
|
quant-ph/0702049 | Akira Furusawa | Jun-ichi Yoshikawa, Toshiki Hayashi, Takayuki Akiyama, Nobuyuki Takei,
Alexander Huck, Ulrik L. Andersen, Akira Furusawa | Demonstration of deterministic and high fidelity squeezing of quantum
information | 5 pages, 4 figures | Phys. Rev. A 76, 060301(R) (2007) | 10.1103/PhysRevA.76.060301 | null | quant-ph | null | By employing at recent proposal (R. Filip, P. Marek and U.L. Andersen, Phys.
Rev. A {\bf 71}, 042308 (2005) \cite{Filip05.pra}), we experimentally
demonstrate a universal, deterministic and high-fidelity squeezing
transformation of an optical field. It relies only on linear optics, homodyne
detection, feedforward and an ancillary squeezed vacuum state, thus direct
interaction between a strong pump and the quantum state is circumvented. We
demonstrate three different squeezing levels for a coherent state input. This
scheme is highly suitable for the fault-tolerant squeezing transformation in a
continuous variable quantum computer.
| [
{
"version": "v1",
"created": "Tue, 6 Feb 2007 07:26:11 GMT"
},
{
"version": "v2",
"created": "Fri, 9 Nov 2007 04:30:57 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Yoshikawa",
"Jun-ichi",
""
],
[
"Hayashi",
"Toshiki",
""
],
[
"Akiyama",
"Takayuki",
""
],
[
"Takei",
"Nobuyuki",
""
],
[
"Huck",
"Alexander",
""
],
[
"Andersen",
"Ulrik L.",
""
],
[
"Furusawa",
"Akira",
""
]
]
|
quant-ph/0702050 | Robert Alicki | Robert Alicki | Comment on "Resilient Quantum Computation in Correlated Environments: A
Quantum Phase Transition Perspective" and "Fault-tolerant Quantum Computation
with Longe-range Correlated Noise" | 2 pages, no figures | null | null | null | quant-ph | null | Critical comments on the recent papers supporting the idea of resilient
quantum computations are presented.
| [
{
"version": "v1",
"created": "Tue, 6 Feb 2007 11:12:21 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Alicki",
"Robert",
""
]
]
|
quant-ph/0702051 | Evandro Silva Ms | D. Galetti and E. C. Silva | Spin tunneling in magnetic molecules: Quantitative estimates for Fe8
clusters | 17 pages, 2 figures, preprint submitted to Physica A | null | 10.1016/j.physa.2007.07.071 | null | quant-ph | null | Spin tunneling in the particular case of the magnetic molecular cluster
octanuclear iron(III), Fe8, is treated by an effective Hamiltonian that allows
for an angle-based description of the process. The presence of an external
magnetic field along the easy axis is also taken into account in this
description. Analytic expressions for the energy levels and barriers are
obtained from a harmonic approximation of the potential function which give
results in good agreement with the experimental results. The energy splittings
due to spin tunneling is treated in an adapted WKB approach and it is shown
that the present description can give results to a reliable degree of accuracy.
| [
{
"version": "v1",
"created": "Tue, 6 Feb 2007 13:06:48 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Galetti",
"D.",
""
],
[
"Silva",
"E. C.",
""
]
]
|
quant-ph/0702052 | Ramazan Sever | Sameer M. Ikhdair, Ramazan Sever | On the solutions of the Schrodinger equation with some molecular
potentials: wave function ansatz | 14 pages | Cent. Eur. J. Phys. 6, 697(2008) | 10.2478/s11534-008-0060-y | null | quant-ph | null | Making an ansatz to the wave function, the exact solutions of the $D$%
-dimensional radial Schrodinger equation with some molecular potentials like
pseudoharmonic and modified Kratzer potentials are obtained. The restriction on
the parameters of the given potential, $\delta $ and $\eta $ are also given,
where $\eta $ depends on a linear combination of the angular momentum quantum
number $\ell $ and the spatial dimensions $D$ and $\delta $ is a parameter in
the ansatz to the wave function. On inserting D=3, we find that the bound state
eigensolutions recover their standard analytical forms in literature.
| [
{
"version": "v1",
"created": "Tue, 6 Feb 2007 13:16:02 GMT"
},
{
"version": "v2",
"created": "Mon, 12 Feb 2007 09:12:03 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Ikhdair",
"Sameer M.",
""
],
[
"Sever",
"Ramazan",
""
]
]
|
quant-ph/0702053 | Stefano Zippilli | Marc Bienert, J. Mauricio Torres, Stefano Zippilli, Giovanna Morigi | Resonance fluorescence of a cold atom in a high-finesse resonator | 10 pages, 7 figures,version accepted for publication in Phys. Rev. A | Phys. Rev. A 76, 013410 (2007) | 10.1103/PhysRevA.76.013410 | null | quant-ph cond-mat.other physics.atom-ph | null | We study the spectra of emission of a system composed by an atom, tightly
confined inside a high-finesse resonator, when the atom is driven by a laser
and is at steady state of the cooling dynamics induced by laser and cavity
field. In general, the spectrum of resonance fluorescence and the spectrum at
the cavity output contain complementary information about the dynamics
undergone by the system. In certain parameter regimes, quantum interference
effects between the scattering processes induced by cavity and laser field lead
to the selective suppression of features of the resonance fluorescence
spectrum, which are otherwise visible in the spectrum of laser-cooled atoms in
free space.
| [
{
"version": "v1",
"created": "Tue, 6 Feb 2007 15:07:08 GMT"
},
{
"version": "v2",
"created": "Thu, 10 May 2007 10:22:26 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Bienert",
"Marc",
""
],
[
"Torres",
"J. Mauricio",
""
],
[
"Zippilli",
"Stefano",
""
],
[
"Morigi",
"Giovanna",
""
]
]
|
quant-ph/0702054 | Federico Casagrande | P. Lougovski, F. Casagrande, A. Lulli, E. Solano | Strongly-Driven One-Atom Laser and Decoherence Monitoring | 9 pages, 7 figures Accepted in Phys. Rev. A | Phys. Rev. A 76, 033802 (2007) | null | null | quant-ph | null | We propose the implementation of a strongly-driven one-atom laser, based on
the off-resonant interaction of a three-level atom in $\Lambda$-configuration
with a single cavity mode and three laser fields. We show that the system can
be described equivalently by a two-level atom resonantly coupled to the cavity
and driven by a strong effective coherent field. The effective dynamics can be
solved exactly, including a thermal field bath, allowing an analytical
description of field statistics and entanglement properties. We also show the
possible generation of Schr\"odinger cat states for the whole atom-field system
and for the field alone after atomic measurement. We propose a way to monitor
the system decoherence by measuring atomic population. Finally, we confirm the
validity of our model through numerical solutions.
| [
{
"version": "v1",
"created": "Tue, 6 Feb 2007 15:32:58 GMT"
},
{
"version": "v2",
"created": "Wed, 7 Feb 2007 13:54:57 GMT"
},
{
"version": "v3",
"created": "Thu, 26 Jul 2007 15:08:59 GMT"
}
]
| 2007-09-10T00:00:00 | [
[
"Lougovski",
"P.",
""
],
[
"Casagrande",
"F.",
""
],
[
"Lulli",
"A.",
""
],
[
"Solano",
"E.",
""
]
]
|
quant-ph/0702055 | Matteo G. A. Paris | Sabrina Maniscalco, Stefano Olivares, Matteo G. A. Paris | Entanglement oscillations in non-Markovian quantum channels | 5 pages, 2 figures, published version | Phys. Rev. A 75, 062119 (2007) | 10.1103/PhysRevA.75.062119 | null | quant-ph | null | We study the non-Markovian dynamics of a two-mode bosonic system interacting
with two uncorrelated thermal bosonic reservoirs. We present the solution to
the exact microscopic Master equation in terms of the quantum characteristic
function and study in details the dynamics of entanglement for bipartite
Gaussian states. In particular, we analyze the effects of short-time
system-reservoir correlations on the separability thresholds and show that the
relevant parameter is the reservoir spectral density. If the frequencies of the
involved modes are within the reservoir spectral density entanglement persists
for a longer time than in a Markovian channel. On the other hand, when the
reservoir spectrum is out of resonance short-time correlations lead to a faster
decoherence and to the appearance of entanglement oscillations.
| [
{
"version": "v1",
"created": "Tue, 6 Feb 2007 17:31:42 GMT"
},
{
"version": "v2",
"created": "Sun, 29 Apr 2007 20:46:59 GMT"
},
{
"version": "v3",
"created": "Wed, 4 Jul 2007 09:01:35 GMT"
}
]
| 2007-07-04T00:00:00 | [
[
"Maniscalco",
"Sabrina",
""
],
[
"Olivares",
"Stefano",
""
],
[
"Paris",
"Matteo G. A.",
""
]
]
|
quant-ph/0702056 | Zhe-Yu Jeff Ou | F. W. Sun, B. H. Liu, Y. X. Gong, Y. F. Huang, Z. Y. Ou, G. C. Guo | Stimulated emission of two photons in parametric amplification and its
interpretation as multi-photon interference | null | null | null | null | quant-ph | null | Stimulated emission of two photons is observed experimentally in the
parametric amplification process and is compared to a three-photon interference
scheme. We find that the underlying physics of stimulated emission is simply
the constructive interference due to photon indistinguishability. So the
observed signal enhancement upon the input of photons is a result of
multi-photon interference of the input photons and the otherwise spontaneously
emitted photon from the amplifier.
| [
{
"version": "v1",
"created": "Tue, 6 Feb 2007 19:57:15 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Sun",
"F. W.",
""
],
[
"Liu",
"B. H.",
""
],
[
"Gong",
"Y. X.",
""
],
[
"Huang",
"Y. F.",
""
],
[
"Ou",
"Z. Y.",
""
],
[
"Guo",
"G. C.",
""
]
]
|
quant-ph/0702057 | Chin-wen Chou | Chin-Wen Chou, Julien Laurat, Hui Deng, Kyung Soo Choi, Hugues de
Riedmatten, Daniel Felinto, H. Jeff Kimble (California Institute of
Technology, Pasadena, California, USA) | Functional Quantum Nodes for Entanglement Distribution over Scalable
Quantum Networks | 10 pages, 7 figures. Text revised, additional information included in
Appendix. Published online in Science Express, 5 April, 2007 | Science 316, 1316 (2007) | 10.1126/science.1140300 | null | quant-ph | null | We demonstrate entanglement distribution between two remote quantum nodes
located 3 meters apart. This distribution involves the asynchronous preparation
of two pairs of atomic memories and the coherent mapping of stored atomic
states into light fields in an effective state of near maximum polarization
entanglement. Entanglement is verified by way of the measured violation of a
Bell inequality, and can be used for communication protocols such as quantum
cryptography. The demonstrated quantum nodes and channels can be used as
segments of a quantum repeater, providing an essential tool for robust
long-distance quantum communication.
| [
{
"version": "v1",
"created": "Tue, 6 Feb 2007 21:19:19 GMT"
},
{
"version": "v2",
"created": "Thu, 12 Apr 2007 05:49:55 GMT"
}
]
| 2011-10-31T00:00:00 | [
[
"Chou",
"Chin-Wen",
"",
"California Institute of\n Technology, Pasadena, California, USA"
],
[
"Laurat",
"Julien",
"",
"California Institute of\n Technology, Pasadena, California, USA"
],
[
"Deng",
"Hui",
"",
"California Institute of\n Technology, Pasadena, California, USA"
],
[
"Choi",
"Kyung Soo",
"",
"California Institute of\n Technology, Pasadena, California, USA"
],
[
"de Riedmatten",
"Hugues",
"",
"California Institute of\n Technology, Pasadena, California, USA"
],
[
"Felinto",
"Daniel",
"",
"California Institute of\n Technology, Pasadena, California, USA"
],
[
"Kimble",
"H. Jeff",
"",
"California Institute of\n Technology, Pasadena, California, USA"
]
]
|
quant-ph/0702058 | Horace P. Yuen | Horace P. Yuen | Mathematical Modeling of Physical and Engineering Systems in Quantum
Information | Conference Proceedings Article of an invited talk at QCMC2006;
revised version with note added in Section 3 | null | null | null | quant-ph | null | Several concrete examples in quantum information are discussed to demonstrate
the importance of proper modeling that relates the mathematical description to
real-world applications. In particular, it is shown that some commonly accepted
conclusions are not adequately supported by their purported justifications in
the logical manner required.
| [
{
"version": "v1",
"created": "Tue, 6 Feb 2007 21:41:41 GMT"
},
{
"version": "v2",
"created": "Thu, 1 Mar 2007 20:53:36 GMT"
},
{
"version": "v3",
"created": "Mon, 19 Mar 2007 02:53:06 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Yuen",
"Horace P.",
""
]
]
|
quant-ph/0702059 | S. Virmani | M. B. Plenio, S. Virmani | Spin chains and channels with memory | V2: changes in presentation, some additional comments on
generalisation. V3: In accordance with published version, most (but not all)
details of proofs now included. A separate paper will shortly be submitted
separately with all details and more results | Phys. Rev. Lett. 99, 120504 (2007) | 10.1103/PhysRevLett.99.120504 | null | quant-ph | null | In most studies of the channel capacity of quantum channels, it is assumed
that the errors in each use of the channel are independent. However, recent
work has begun to investigate the effects of memory or correlations in the
error. This work has led to speculation that interesting non-analytic behaviour
may occur in the capacity. Motivated by these observations, we connect the
study of channel capacities under correlated error to the study of critical
behaviour in many-body physics. This connection enables us the techniques of
many-body physics to either completely solve or understand qualitatively a
number of interesting models of correlated error. The models can display
analogous behaviour to associated many-body systems, including `phase
transitions'.
| [
{
"version": "v1",
"created": "Tue, 6 Feb 2007 22:06:47 GMT"
},
{
"version": "v2",
"created": "Fri, 20 Apr 2007 19:07:05 GMT"
},
{
"version": "v3",
"created": "Tue, 16 Oct 2007 17:26:38 GMT"
}
]
| 2007-10-16T00:00:00 | [
[
"Plenio",
"M. B.",
""
],
[
"Virmani",
"S.",
""
]
]
|
quant-ph/0702060 | Galina L. Klimchitskaya | F.Chen, U.Mohideen, G.L.Klimchitskaya, and V.M.Mostepanenko | Comment on ``Lateral Casimir force beyond the proximity-force
approximation'' | 2 pages | Phys.Rev.Lett.98:068901,2007 | 10.1103/PhysRevLett.98.068901 | null | quant-ph cond-mat.stat-mech hep-th | null | We demonstrate that the approach by Rodrigues et al. (PRL, v.96, 100402,
2006) to the description of the lateral Casimir force between corrugated
surfaces is in disagreement with a path-integral theory by Emig et al. (PRA,
v.67, 022114, 2003), and the approximations used are not appropriate for
comparison to experiment.
| [
{
"version": "v1",
"created": "Tue, 6 Feb 2007 22:27:35 GMT"
}
]
| 2008-11-26T00:00:00 | [
[
"Chen",
"F.",
""
],
[
"Mohideen",
"U.",
""
],
[
"Klimchitskaya",
"G. L.",
""
],
[
"Mostepanenko",
"V. M.",
""
]
]
|
quant-ph/0702061 | Galina L. Klimchitskaya | V.M.Mostepanenko | The Casimir Effect in Relativistic Quantum Field Theories | 20 pages, 4 figures, uses ws-procs975x65.cls, to appear in
Proceedings of 11th Marsel Grossmann Meeting on General Relativity (Berlin,
2006) | null | 10.1142/9789812834300_0501 | null | quant-ph cond-mat.stat-mech hep-th | null | We review recent developments in the Casimir effect which arises in
quantization volumes restricted by material boundaries and in spaces with
non-Euclidean topology. The starting point of our discussion is the novel exact
solution for the electromagnetic Casimir force in the configuration of a
cylinder above a plate. The related work for the scalar Casimir effect in
sphere-plate configuration is also considered, and the application region of
the proximity force theorem is discussed. Next we consider new experiments on
the measurement of the Casimir force between metals and between metal and
semiconductor. The complicated problem connected with the theory of the thermal
Casimir force between real metals is analyzed in detail. The present situation
regarding different theoretical approaches to the resolution of this problem is
summarized. We conclude with new constraints on non-Newtonian gravity obtained
using the results of latest Casimir force measurements and compare them with
constraints following from the most recent gravitational experiments.
| [
{
"version": "v1",
"created": "Tue, 6 Feb 2007 22:44:58 GMT"
}
]
| 2016-11-15T00:00:00 | [
[
"Mostepanenko",
"V. M.",
""
]
]
|
quant-ph/0702062 | Gong Zhe-Xuan | Wen-Xing Yang and Zhe-Xuan Gong | Practical scheme for quantum dense coding between three parties using
microwave radiation in trapped ions | 6 pages, 2 figures, accepted by J. Phys. B: At. Mol. Opt. Phys | J. Phys. B: At. Mol. Opt. Phys. 40 (2007) 1245-1252 | 10.1088/0953-4075/40/6/014 | null | quant-ph | null | We propose a practical scheme for implementing two-dimension quantum dense
coding (QDC) between three parties through manipulating three ions confined in
microtraps addressed by microwaves and assisted by a magnetic field gradient.
The ions in our scheme are not required to be strictly cooled to the
vibrational ground state because single-qubit and multi-qubit operations are
made via Ising terms, in which the vibrational modes of the ions remain
unchanged throughout the scheme, rendering our scheme robust to the heating of
the ions. We also present the detailed steps and parameters for implementing
the three-party QDC experimentally and show that the proposed scheme is within
the current techniques of ion-trap experiments.
| [
{
"version": "v1",
"created": "Wed, 7 Feb 2007 03:42:30 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Yang",
"Wen-Xing",
""
],
[
"Gong",
"Zhe-Xuan",
""
]
]
|
quant-ph/0702063 | Boris Levin | B.M. Levin and V.I. Sokolov | On an additional realization of supersymmetry in orthopositronium
lifetime anomalies | 9 pages, 3 figures | null | null | null | quant-ph | null | Expansion of Standard Model for the quantitative description of the
orthopositronium lifetime anomalies (from QED to supersymmetric QED) allows to
formulate experimental tests of supervision of additional realization of the
supersymmetry in final state of the positron beta-decay of the nuclei such as
Na-22, Ga-68. The expermentum crucis program is based on supervision of the
orthopositronium "isotope anomaly", on the quantitative description of the
"lifetime anomaly", and will allow to resolve the alternative as results of the
last Michigan work (2003).
| [
{
"version": "v1",
"created": "Wed, 7 Feb 2007 07:52:33 GMT"
},
{
"version": "v2",
"created": "Fri, 16 Mar 2007 07:19:16 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Levin",
"B. M.",
""
],
[
"Sokolov",
"V. I.",
""
]
]
|
quant-ph/0702064 | Peter Rohde | Peter P. Rohde, Austin P. Lund | Practical effects in cat state breeding | 3 pages | null | null | null | quant-ph | null | A cat state is a superposition of macroscopically distinct states. In quantum
optics one such type of state is a superposition of distinct coherent states.
Recently, a protocol has been proposed for preparing large optical cat states
from a resource of smaller ones. We consider the effects of mode-mismatch and
loss in the preparation of large cat states using this protocol with a view to
understand experimental limitations. (This paper is written in an experimental
rapid communication format).
| [
{
"version": "v1",
"created": "Wed, 7 Feb 2007 09:39:05 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Rohde",
"Peter P.",
""
],
[
"Lund",
"Austin P.",
""
]
]
|
quant-ph/0702065 | Peter Rohde | Peter P. Rohde | Noise thresholds for entanglement purification | 2 pages, references added | null | null | null | quant-ph | null | We consider the effects of gate noise on the operation of an entanglement
purification protocol. We characterize the performance of the protocol by two
measures, the minimum purifiable input state fidelity, and the maximum output
state fidelity. Both these measures are a function of gate error rate. For
sufficiently large gate error rate these two measures converge, defining a
threshold on gate error rates. Numerically, we estimate this threshold to be
$9.2\times 10^{-2}$, which is achievable with many present day experimental
architectures. (This paper is written in an experimental rapid communication
format).
| [
{
"version": "v1",
"created": "Wed, 7 Feb 2007 09:44:42 GMT"
},
{
"version": "v2",
"created": "Wed, 7 Mar 2007 00:37:37 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Rohde",
"Peter P.",
""
]
]
|
quant-ph/0702066 | Ramin Golestanian | Arash Ashourvan, MirFaez Miri, and Ramin Golestanian | Rectification of the lateral Casimir force in a vibrating non-contact
rack and pinion | null | Phys. Rev. E 75, 040103 (R) (2007) | 10.1103/PhysRevE.75.040103 | null | quant-ph cond-mat.stat-mech | null | The nonlinear dynamics of a cylindrical pinion that is kept at a distance
from a vibrating rack is studied, and it is shown that the lateral Casimir
force between the two corrugated surfaces can be rectified. The effects of
friction and external load are taken into account and it is shown that the
pinion can do work against loads of up to a critical value, which is set by the
amplitude of the lateral Casimir force. We present a phase diagram for the
rectified motion that could help its experimental investigations, as the system
exhibits a chaotic behavior in a large part of the parameter space.
| [
{
"version": "v1",
"created": "Wed, 7 Feb 2007 11:35:35 GMT"
},
{
"version": "v2",
"created": "Wed, 2 May 2007 08:46:15 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Ashourvan",
"Arash",
""
],
[
"Miri",
"MirFaez",
""
],
[
"Golestanian",
"Ramin",
""
]
]
|
quant-ph/0702067 | Libby Heaney | Libby Heaney, Janet Anders, Dagomir Kaszlikowski, Vlatko Vedral | Spatial Entanglement From Off-Diagonal Long Range Order in a BEC | 7 pages, 3 figures. Extended from 4 to 7 pages. More detailed
derivations of key formula. Extended introduction and background. Results
remain unchanged | Phys. Rev. A, 76 053605 (2007) | 10.1103/PhysRevA.76.053605 | null | quant-ph | null | We investigate spatial entanglement - particle-number entanglement between
regions of space - in an ideal Bosonic gas. We quantify the amount spatial
entanglement around the transition temperature for condensation by probing the
gas with two localised two-level systems. We show that spatial entanglement in
the gas is directly related to filling of the ground state energy level and
therefore to the off-diagonal long-range order of the system and the onset of
condensation.
| [
{
"version": "v1",
"created": "Wed, 7 Feb 2007 13:56:19 GMT"
},
{
"version": "v2",
"created": "Wed, 26 Sep 2007 11:06:23 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Heaney",
"Libby",
""
],
[
"Anders",
"Janet",
""
],
[
"Kaszlikowski",
"Dagomir",
""
],
[
"Vedral",
"Vlatko",
""
]
]
|
quant-ph/0702068 | Giulio Chiribella | G. Chiribella, G.M. D'Ariano, and D. M. Schlingemann | How continuous quantum measurements in finite dimension are actually
discrete | 4 pages, 1 figure | Phys. Rev. Lett. 98, 190403 (2007) | 10.1103/PhysRevLett.98.190403 | null | quant-ph | null | We show that in finite dimension a quantum measurement with continuous set of
outcomes is always equivalent to a continuous random choice of measurements
with only finite outcomes.
| [
{
"version": "v1",
"created": "Wed, 7 Feb 2007 14:33:23 GMT"
}
]
| 2010-05-04T00:00:00 | [
[
"Chiribella",
"G.",
""
],
[
"D'Ariano",
"G. M.",
""
],
[
"Schlingemann",
"D. M.",
""
]
]
|
quant-ph/0702069 | Gerardo Adesso | Gerardo Adesso | Entanglement of Gaussian states | Ph.D. Thesis, University of Salerno. 296 pages, many (heavily
compressed) figures. Hi-res version downloadable at
http://www.sa.infn.it/quantumtheory/attach/Adesso_PhD.pdf (PDF 11Mb) | null | null | null | quant-ph cond-mat.stat-mech hep-th math-ph math.MP physics.comp-ph physics.optics | null | This Dissertation collects my results on the interpretation,
characterization, quantification and application of bipartite and multipartite
entanglement in Gaussian states of continuous variable systems.
| [
{
"version": "v1",
"created": "Wed, 7 Feb 2007 15:05:27 GMT"
}
]
| 2016-09-08T00:00:00 | [
[
"Adesso",
"Gerardo",
""
]
]
|
quant-ph/0702070 | Isabel P\'erez-Arjona | Isabel Perez-Arjona, Eugenio Roldan and German J. de Valcarcel | Theory of quantum fluctuations of optical dissipative structures and its
application to the squeezing properties of bright cavity solitons | 10 figures | Physical Review A 75, 063802 (2007) | 10.1103/PhysRevA.75.063802 | null | quant-ph | null | We present a method for the study of quantum fluctuations of dissipative
structures forming in nonlinear optical cavities, which we illustrate in the
case of a degenerate, type I optical parametric oscillator. The method consists
in (i) taking into account explicitly, through a collective variable
description, the drift of the dissipative structure caused by the quantum
noise, and (ii) expanding the remaining -internal- fluctuations in the
biorthonormal basis associated to the linear operator governing the evolution
of fluctuations in the linearized Langevin equations. We obtain general
expressions for the squeezing and intensity fluctuations spectra. Then we
theoretically study the squeezing properties of a special dissipative
structure, namely, the bright cavity soliton. After reviewing our previous
result that in the linear approximation there is a perfectly squeezed mode
irrespectively of the values of the system parameters, we consider squeezing at
the bifurcation points, and the squeezing detection with a plane--wave local
oscillator field, taking also into account the effect of the detector size on
the level of detectable squeezing.
| [
{
"version": "v1",
"created": "Wed, 7 Feb 2007 17:41:29 GMT"
}
]
| 2007-07-31T00:00:00 | [
[
"Perez-Arjona",
"Isabel",
""
],
[
"Roldan",
"Eugenio",
""
],
[
"de Valcarcel",
"German J.",
""
]
]
|
quant-ph/0702071 | Florian Rempp | F.Rempp, M. Michel, G. Mahler | A Cyclic Cooling Algorithm | null | null | 10.1103/PhysRevA.76.032325 | null | quant-ph | null | We introduce a scheme to perform the cooling algorithm, first presented by
Oscar Boykin et al. in 2002, for an arbitrary number of times on the same set
of qbits. We achieve this goal by adding an additional SWAP-gate and a bath
contact to the algorithm. This way one qbit may repeatedly be cooled without
adding additional qbits to the system. By using a product Liouville space to
model the bath contact we calculate the density matrix of the system after a
given number of applications of the algorithm.
| [
{
"version": "v1",
"created": "Wed, 7 Feb 2007 17:34:59 GMT"
},
{
"version": "v2",
"created": "Mon, 3 Sep 2007 11:16:19 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Rempp",
"F.",
""
],
[
"Michel",
"M.",
""
],
[
"Mahler",
"G.",
""
]
]
|
quant-ph/0702072 | Lukasz Swiatczak | Pierfrancesco La Mura and Lukasz Swiatczak | Markovian Entanglement Networks | 7 pages, 3 figures, uses aaai.sty | null | null | HHL-77 | quant-ph cs.AI | null | Graphical models of probabilistic dependencies have been extensively
investigated in the context of classical uncertainty. However, in some domains
(most notably, in computational physics and quantum computing) the nature of
the relevant uncertainty is non-classical, and the laws of classical
probability theory are superseded by those of quantum mechanics. In this paper
we introduce Markovian Entanglement Networks (MEN), a novel class of graphical
representations of quantum-mechanical dependencies in the context of such
non-classical systems. MEN are the quantum-mechanical analogue of Markovian
Networks, a family of undirected graphical representations which, in the
classical domain, exploit a notion of conditional independence among
subsystems.
After defining a notion of conditional independence appropriate to our domain
(conditional separability), we prove that the conditional separabilities
induced by a quantum-mechanical wave function are effectively reflected in the
graphical structure of MEN. Specifically, we show that for any wave function
there exists a MEN which is a perfect map of its conditional separabilities.
Next, we show how the graphical structure of MEN can be used to effectively
classify the pure states of three-qubit systems. We also demonstrate that, in
large systems, exploiting conditional independencies may dramatically reduce
the computational burden of various inference tasks. In principle, the
graph-theoretic representation of conditional independencies afforded by MEN
may not only facilitate the classical simulation of quantum systems, but also
provide a guide to the efficient design and complexity analysis of quantum
algorithms and circuits.
| [
{
"version": "v1",
"created": "Wed, 7 Feb 2007 18:39:42 GMT"
}
]
| 2011-11-09T00:00:00 | [
[
"La Mura",
"Pierfrancesco",
""
],
[
"Swiatczak",
"Lukasz",
""
]
]
|
quant-ph/0702073 | Philip Feinsilver | Philip Feinsilver, Jerzy Kocik | Krawtchouk polynomials and Krawtchouk matrices | null | Recent advances in applied probability, Springer-Verlag, October,
2004 | null | null | quant-ph | null | Krawtchouk matrices have as entries values of the Krawtchouk polynomials for
nonnegative integer arguments. We show how they arise as condensed
Sylvester-Hadamard matrices via a binary shuffling function. The underlying
symmetric tensor algebra is presented. Our approach is used to solve Kac'
formulation of the Ehrenfest urn model. Connections with quantum and classical
random walks are shown as well as various extensions of the classical
polynomials.
| [
{
"version": "v1",
"created": "Wed, 7 Feb 2007 20:20:23 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Feinsilver",
"Philip",
""
],
[
"Kocik",
"Jerzy",
""
]
]
|
quant-ph/0702074 | Horace P. Yuen | Horace P. Yuen | QBC3: An Unconditionally Secure Quantum Bit Commitment Protocol | Conference Proceedings article of a submission to QCMC 2006; revised
version | null | null | null | quant-ph | null | This article describes a quantum bit commitment protocol, QBC3, based on
entanglement destruction via forced measurements and proves its unconditional
security. Some comments on the current status of the field are also made.
| [
{
"version": "v1",
"created": "Wed, 7 Feb 2007 20:32:18 GMT"
},
{
"version": "v2",
"created": "Thu, 1 Mar 2007 20:51:18 GMT"
},
{
"version": "v3",
"created": "Fri, 9 Mar 2007 04:20:29 GMT"
},
{
"version": "v4",
"created": "Mon, 19 Mar 2007 02:47:15 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Yuen",
"Horace P.",
""
]
]
|
quant-ph/0702075 | Wojciech Wasilewski | Wojciech Wasilewski and Konrad Banaszek | Protecting an optical qubit against photon loss | null | Phys. Rev. A 75, 042316 (2007) | 10.1103/PhysRevA.75.042316 | null | quant-ph | null | We consider quantum error-correction codes for multimode bosonic systems,
such as optical fields, that are affected by amplitude damping. Such a process
is a generalization of an erasure channel. We demonstrate that the most
accessible method of transforming optical systems with the help of passive
linear networks has limited usefulness in preparing and manipulating such
codes. These limitations stem directly from the recoverability condition for
one-photon loss. We introduce a three-photon code protecting against the first
order of amplitude damping, i.e. a single photon loss, and discuss its
preparation using linear optics with single-photon sources and conditional
detection. Quantum state and process tomography in the code subspace can be
implemented using passive linear optics and photon counting. An experimental
proof-of-principle demonstration of elements of the proposed quantum error
correction scheme for a one-photon erasure lies well within present
technological capabilites.
| [
{
"version": "v1",
"created": "Wed, 7 Feb 2007 21:46:34 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Wasilewski",
"Wojciech",
""
],
[
"Banaszek",
"Konrad",
""
]
]
|
quant-ph/0702076 | Constantin V. Usenko | Constantin V. Usenko | Classification of two-particle quantum channels of information transfer | To appear in Bulletin of the University of Kiev. Series: Physics &
Mathematics (translated from Ukrainian). Extended version of quant-ph/0702043 | null | null | null | quant-ph | null | Classification of states of two-particle quantum channels of information
transfer is built on the basis of irreducible representations of qubit state
space group of symmetry and properties of density matrix spectrum. It is shown
that the reason of state disentanglement can be in degeneration of non-zero
density matrix eigenvalues. Among the states with non-degenerate density matrix
disentangled states form two-dimensional surface of special states.
| [
{
"version": "v1",
"created": "Wed, 7 Feb 2007 22:15:42 GMT"
},
{
"version": "v2",
"created": "Sat, 10 Feb 2007 00:13:11 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Usenko",
"Constantin V.",
""
]
]
|
quant-ph/0702077 | Jonathan Oppenheim | Karol Horodecki, Michal Horodecki, Pawel Horodecki, Debbie Leung,
Jonathan Oppenheim | Unconditional privacy over channels which cannot convey quantum
information | Related to quant-ph/0608195 and for a more general audience | Phys. Rev. Lett. 100, 110502 (2008) | 10.1103/PhysRevLett.100.110502 | null | quant-ph | null | By sending systems in specially prepared quantum states, two parties can
communicate without an eavesdropper being able to listen. The technique, called
quantum cryptography, enables one to verify that the state of the quantum
system has not been tampered with, and thus one can obtain privacy regardless
of the power of the eavesdropper. All previous protocols relied on the ability
to faithfully send quantum states. In fact, until recently, they could all be
reduced to a single protocol where security is ensured though sharing maximally
entangled states. Here we show this need not be the case -- one can obtain
verifiable privacy even through some channels which cannot be used to reliably
send quantum states.
| [
{
"version": "v1",
"created": "Thu, 8 Feb 2007 00:54:28 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Horodecki",
"Karol",
""
],
[
"Horodecki",
"Michal",
""
],
[
"Horodecki",
"Pawel",
""
],
[
"Leung",
"Debbie",
""
],
[
"Oppenheim",
"Jonathan",
""
]
]
|
quant-ph/0702078 | Hong Shen | M.X. Huo, Ying Li, Z. Song, and C.P. Sun | Atomic Entanglement vs Photonic Visibility for Quantum Criticality of
Hybrid System | 4 pages, 2 figures | Phys. Rev. A 77, 022103 (2008) | 10.1103/PhysRevA.77.022103 | null | quant-ph cond-mat.mes-hall | null | To characterize the novel quantum phase transition for a hybrid system
consisting of an array of coupled cavities and two-level atoms doped in each
cavity, we study the atomic entanglement and photonic visibility in comparison
with the quantum fluctuation of total excitations. Analytical and numerical
simulation results show the happen of quantum critical phenomenon similar to
the Mott insulator to superfluid transition. Here, the contour lines
respectively representing the atomic entanglement, photonic visibility and
excitation variance in the phase diagram are consistent in the vicinity of the
non-analytic locus of atomic concurrences.
| [
{
"version": "v1",
"created": "Thu, 8 Feb 2007 02:34:35 GMT"
},
{
"version": "v2",
"created": "Mon, 12 Feb 2007 04:57:35 GMT"
}
]
| 2009-01-06T00:00:00 | [
[
"Huo",
"M. X.",
""
],
[
"Li",
"Ying",
""
],
[
"Song",
"Z.",
""
],
[
"Sun",
"C. P.",
""
]
]
|
quant-ph/0702079 | Fernando de Melo | F. de Melo, S. P. Walborn, J\'anos A. Bergou, L. Davidovich | Quantum Non-Demolition Test of Bipartite Complementarity | 4 pages, 2 figures | Phys. Rev. Lett. 98, 250501 (2007) | 10.1103/PhysRevLett.98.250501 | null | quant-ph | null | We present a quantum circuit that implements a non-demolition measurement of
complementary single- and bi-partite properties of a two-qubit system:
entanglement and single-partite visibility and predictability. The system must
be in a pure state with real coefficients in the computational basis, which
allows a direct operational interpretation of those properties. The circuit can
be realized in many systems of interest to quantum information.
| [
{
"version": "v1",
"created": "Thu, 8 Feb 2007 10:42:28 GMT"
}
]
| 2007-06-20T00:00:00 | [
[
"de Melo",
"F.",
""
],
[
"Walborn",
"S. P.",
""
],
[
"Bergou",
"János A.",
""
],
[
"Davidovich",
"L.",
""
]
]
|
quant-ph/0702080 | Mark Williamson | Mark Williamson, Vlatko Vedral | Composite Geometric Phase for Multipartite Entangled States | 4 pages, 1 figure, improved presentation, results and conclusions
unchanged from v1. Accepted for publication in PRA | Phys. Rev. A 76, 032115 (2007) | 10.1103/PhysRevA.76.032115 | null | quant-ph | null | When an entangled state evolves under local unitaries, the entanglement in
the state remains fixed. Here we show the dynamical phase acquired by an
entangled state in such a scenario can always be understood as the sum of the
dynamical phases of its subsystems. In contrast, the equivalent statement for
the geometric phase is not generally true unless the state is separable. For an
entangled state an additional term is present, the mutual geometric phase, that
measures the change the additional correlations present in the entangled state
make to the geometry of the state space. For $N$ qubit states we find this
change can be explained solely by classical correlations for states with a
Schmidt decomposition and solely by quantum correlations for W states.
| [
{
"version": "v1",
"created": "Thu, 8 Feb 2007 12:39:30 GMT"
},
{
"version": "v2",
"created": "Tue, 7 Aug 2007 01:51:47 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Williamson",
"Mark",
""
],
[
"Vedral",
"Vlatko",
""
]
]
|
quant-ph/0702081 | Marcos C. de Oliveira | Luis F. Haruna, Marcos C. de Oliveira, Gustavo Rigolin | Minimal set of local measurements and classical communication for
two-mode Gaussian state entanglement quantification | 5 pages, 1 figure. Replaced with final published version | Phys. Rev. Lett. 98, 150501 (2007); Phys. Rev. Lett. 99, 059902
(2007) | 10.1103/PhysRevLett.99.059902 | null | quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We develop the minimal requirements for the complete entanglement
quantification of an arbitrary two-mode bipartite Gaussian state via local
measurements and a classical communication channel. The minimal set of
measurements is presented as a reconstruction protocol of local covariance
matrices and no previous knowledge of the state is required but its Gaussian
character. The protocol becomes very simple mostly when dealing with Gaussian
states transformed to its standard form, since photocounting/intensity
measurements define the whole set of entangled states. In addition, conditioned
on some prior information, the protocol is also useful for a complete global
state reconstruction.
| [
{
"version": "v1",
"created": "Thu, 8 Feb 2007 19:12:28 GMT"
},
{
"version": "v2",
"created": "Fri, 9 Feb 2007 12:55:03 GMT"
},
{
"version": "v3",
"created": "Wed, 9 Jul 2008 13:19:29 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Haruna",
"Luis F.",
""
],
[
"de Oliveira",
"Marcos C.",
""
],
[
"Rigolin",
"Gustavo",
""
]
]
|
quant-ph/0702082 | Kai Eckert | K. Eckert, O. Romero-Isart, and A. Sanpera | Efficient quantum state transfer in spin chains via adiabatic passage | 14 pages, 6 figures, to be published in New J. Phys | New J. Phys. 9, 155 (2007) | 10.1088/1367-2630/9/5/155 | null | quant-ph | null | We propose a method for quantum state transfer in spin chains using an
adiabatic passage technique. Modifying even and odd nearest-neighbour couplings
in time allows to achieve transfer fidelities arbitrarily close to one, without
the need for a precise control of coupling strengths and timing. We study in
detail transfer by adiabatic passage in a spin-1 chain governed by a
generalized Heisenberg Hamiltonian. We consider optimization of the transfer
process applying optimal control techniques. We discuss a realistic
experimental implementation using cold atomic gases confined in deep optical
lattices.
| [
{
"version": "v1",
"created": "Thu, 8 Feb 2007 20:41:14 GMT"
},
{
"version": "v2",
"created": "Thu, 3 May 2007 15:55:15 GMT"
}
]
| 2007-06-13T00:00:00 | [
[
"Eckert",
"K.",
""
],
[
"Romero-Isart",
"O.",
""
],
[
"Sanpera",
"A.",
""
]
]
|
quant-ph/0702083 | Hoshang Heydari | Hoshang Heydari | Quantum gate entangler for general multipartite systems | 6 pages | Open Systems & Information Dynamics, Vol. 15, No. 3 (2008) 213-222 | null | null | quant-ph | null | We construct quantum gate entangler for general multipartite states based on
topological unitary operators. We show that these operators can entangle
quantum states if they satisfy the separability condition that is given by the
complex multi-projective Segre variety. We also in detail discuss the
construction of quantum gate entangler for higher dimensional bipartite and
three-partite quantum systems.
| [
{
"version": "v1",
"created": "Fri, 9 Feb 2007 04:46:41 GMT"
}
]
| 2008-11-27T00:00:00 | [
[
"Heydari",
"Hoshang",
""
]
]
|
quant-ph/0702084 | Jesni Shamsul Shaari Mr | J.S. Shaari, R.S. Said, M.R.B. Wahiddin | Secure Quantum Telephones | Substantial changes made to ensure security of protocol | null | null | null | quant-ph | null | We propose in this paper a novel deterministic protocol using particular
maximally entangled states of polarized photons for a genuine bidirectional
secure communication setup. We further propose a plausible experimental setup
for such a protocol using currently available optical technology which
liberates two communicating party from sharing identical apparatus. We note
that security of the protocol is promised by the monogamous nature of maximally
entangled states. We discuss the security of our protocol in the light of some
simple eavesdropping scenarios.
| [
{
"version": "v1",
"created": "Fri, 9 Feb 2007 06:59:45 GMT"
},
{
"version": "v2",
"created": "Thu, 8 Mar 2007 03:23:02 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Shaari",
"J. S.",
""
],
[
"Said",
"R. S.",
""
],
[
"Wahiddin",
"M. R. B.",
""
]
]
|
quant-ph/0702085 | Andre Lengwenus | A. Lengwenus, J. Kruse, M. Volk, W. Ertmer, G. Birkl | Coherent manipulation of atomic qubits in optical micropotentials | to be published in Appl. Phys. B | Appl. Phys. B 86, 377-383 (2007) | 10.1007/s00340-006-2539-9 | null | quant-ph | null | We experimentally demonstrate the coherent manipulation of atomic states in
far-detuned dipole traps and registers of dipole traps based on two-dimensional
arrays of microlenses. By applying Rabi, Ramsey, and spin-echo techniques, we
systematically investigate the dephasing mechanisms and determine the coherence
time. Simultaneous Ramsey measurements in up to 16 dipole traps are performed
and proves the scalability of our approach. This represents an important step
in the application of scalable registers of atomic qubits for quantum
information processing. In addition, this system can serve as the basis for
novel atomic clocks making use of the parallel operation of a large number of
individual clocks each remaining separately addressable.
| [
{
"version": "v1",
"created": "Fri, 9 Feb 2007 07:37:21 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Lengwenus",
"A.",
""
],
[
"Kruse",
"J.",
""
],
[
"Volk",
"M.",
""
],
[
"Ertmer",
"W.",
""
],
[
"Birkl",
"G.",
""
]
]
|
quant-ph/0702086 | Ling-An Wu | Hai-Qiang Ma, Jian-Ling Zhao, and Ling-An Wu | Quantum key distribution based on phase encoding and polarization
measurement | To appear in Optics Letters | null | 10.1364/OL.32.000698 | null | quant-ph | null | A one-way quantum key distribution scheme based on intrinsically stable
Faraday-mirror type Michelson interferometers with four-port polarizing
beampslitters has been demonstrated which can compensate for birefringence
effects automatically. The encoding is performed with phase modulators, but
decoding is accomplished through measurement of the polarization state of Bob's
photons. An extinction ratio of about 30dB was maintained for several hours
over 50km of fiber at 1310nm without any adjustment to the setup, which shows
its good potential for practical systems
| [
{
"version": "v1",
"created": "Fri, 9 Feb 2007 09:06:55 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Ma",
"Hai-Qiang",
""
],
[
"Zhao",
"Jian-Ling",
""
],
[
"Wu",
"Ling-An",
""
]
]
|
quant-ph/0702087 | P. W. H. Pinkse | T. Puppe, I. Schuster, P. Maunz, K. Murr, P.W.H. Pinkse, G. Rempe | Light force fluctuations in a strongly coupled atom-cavity system | 7 pages, 3 figures | Journal of Modern Optics, 54:13, 1927 - 1937 (2007) | 10.1080/09500340701415578 | null | quant-ph | null | Between mirrors, the density of electromagnetic modes differs from the one in
free space. This changes the radiation properties of an atom as well as the
light forces acting on an atom. It has profound consequences in the
strong-coupling regime of cavity quantum electrodynamics. For a single atom
trapped inside the cavity, we investigate the atom-cavity system by scanning
the frequency of a probe laser for various atom-cavity detunings. The avoided
crossing between atom and cavity resonance is visible in the transmission of
the cavity. It is also visible in the loss rate of the atom from the
intracavity dipole trap. On the normal-mode resonances, the dominant
contribution to the loss rate originates from dipole-force fluctuations which
are dramatically enhanced in the cavity. This conclusion is supported by
Monte-Carlo simulations.
| [
{
"version": "v1",
"created": "Fri, 9 Feb 2007 09:36:03 GMT"
}
]
| 2007-10-04T00:00:00 | [
[
"Puppe",
"T.",
""
],
[
"Schuster",
"I.",
""
],
[
"Maunz",
"P.",
""
],
[
"Murr",
"K.",
""
],
[
"Pinkse",
"P. W. H.",
""
],
[
"Rempe",
"G.",
""
]
]
|
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.