Physical Review Letters
Realization of a Quantum Walk with One and Two Trapped Ions
Author(s): F. Zähringer, G. Kirchmair, R. Gerritsma, E. Solano, R. Blatt, and C. F. Roos
We experimentally demonstrate a quantum walk on a line in phase space using one and two trapped ions. A walk with up to 23 steps is realized by subjecting an ion to state-dependent displacement operations interleaved with quantum coin tossing operations. To analyze the ion’s motional state after e...
[Phys. Rev. Lett. 104, 100503] Published Tue Mar 09, 2010
Experimental Demonstration of Photonic Entanglement Collapse and Revival
Author(s): Jin-Shi Xu, Chuan-Feng Li, Ming Gong, Xu-Bo Zou, Cheng-Hao Shi, Geng Chen, and Guang-Can Guo
We demonstrate the collapse and revival features of the entanglement dynamics of different polarization-entangled photon states in a non-Markovian environment. Using an all-optical experimental setup, we show that entanglement can be revived even after it suffers from sudden death. A maximally reviv...
[Phys. Rev. Lett. 104, 100502] Published Tue Mar 09, 2010
Measuring the Transmission Matrix in Optics: An Approach to the Study and Control of Light Propagation in Disordered Media
Author(s): S. M. Popoff, G. Lerosey, R. Carminati, M. Fink, A. C. Boccara, and S. Gigan
We introduce a method to experimentally measure the monochromatic transmission matrix of a complex medium in optics. This method is based on a spatial phase modulator together with a full-field interferometric measurement on a camera. We determine the transmission matrix of a thick random scattering...
[Phys. Rev. Lett. 104, 100601] Published Mon Mar 08, 2010
Experimental Estimation of Entanglement at the Quantum Limit
Author(s): Giorgio Brida, Ivo Pietro Degiovanni, Angela Florio, Marco Genovese, Paolo Giorda, Alice Meda, Matteo G. A. Paris, and Alexander Shurupov
Entanglement is the central resource of quantum information processing and the precise characterization of entangled states is a crucial issue for the development of quantum technologies. This leads to the necessity of a precise, experimental feasible measure of entanglement. Nevertheless, such meas...
[Phys. Rev. Lett. 104, 100501] Published Mon Mar 08, 2010
Generalized Jarzynski Equality under Nonequilibrium Feedback Control
Author(s): Takahiro Sagawa and Masahito Ueda
The Jarzynski equality is generalized to situations in which nonequilibrium systems are subject to a feedback control. The new terms that arise as a consequence of the feedback describe the mutual information content obtained by measurement and the efficacy of the feedback control. Our results lead ...
[Phys. Rev. Lett. 104, 090602] Published Fri Mar 05, 2010
Microscopic Derivation of Hubbard Parameters for Cold Atomic Gases
Author(s): Hans Peter Büchler
We study the exact solution for two atomic particles in an optical lattice interacting via a Feshbach resonance. The analysis includes the influence of all higher bands, as well as the proper renormalization of molecular energy in the closed channel. This exact solution allows for the precise determ...
[Phys. Rev. Lett. 104, 090402] Published Fri Mar 05, 2010
Arbitrarily Accurate Dynamical Control in Open Quantum Systems
Author(s): Kaveh Khodjasteh, Daniel A. Lidar, and Lorenza Viola
We show that open-loop dynamical control techniques may be used to synthesize unitary transformations in open quantum systems in such a way that decoherence is perturbatively compensated for to a desired (in principle arbitrarily high) level of accuracy, which depends only on the strength of the rel...
[Phys. Rev. Lett. 104, 090501] Published Thu Mar 04, 2010
Maxwell Superalgebra and Superparticles in Constant Gauge Backgrounds
Author(s): Sotirios Bonanos, Joaquim Gomis, Kiyoshi Kamimura, and Jerzy Lukierski
We present the Maxwell superalgebra, an N=1, D=4 algebra with two Majorana supercharges, obtained as the minimal enlargement of a Poincaré superalgebra containing the Maxwell algebra as a subalgebra. The new superalgebra describes the supersymmetries of generalized N=1, D=4 superspace in the presen...
[Phys. Rev. Lett. 104, 090401] Published Thu Mar 04, 2010
Three Detailed Fluctuation Theorems
Author(s): Massimiliano Esposito and Christian Van den Broeck
The total entropy production of a trajectory can be split into an adiabatic and a nonadiabatic contribution, deriving, respectively, from the breaking of detailed balance via nonequilibrium boundary conditions or by external driving. We show that each of them, the total, the adiabatic, and the nonad...
[Phys. Rev. Lett. 104, 090601] Published Mon Mar 01, 2010
Experimental Feedback Control of Quantum Systems Using Weak Measurements
Author(s): G. G. Gillett, R. B. Dalton, B. P. Lanyon, M. P. Almeida, M. Barbieri, G. J. Pryde, J. L. O’Brien, K. J. Resch, S. D. Bartlett, and A. G. White
A goal of the emerging field of quantum control is to develop methods for quantum technologies to function robustly in the presence of noise. Central issues are the fundamental limitations on the available information about quantum systems and the disturbance they suffer in the process of measuremen...
[Phys. Rev. Lett. 104, 080503] Published Fri Feb 26, 2010
Nonequilibrium Fluctuation Relations in a Quantum Coherent Conductor
Author(s): Shuji Nakamura, Yoshiaki Yamauchi, Masayuki Hashisaka, Kensaku Chida, Kensuke Kobayashi, Teruo Ono, Renaud Leturcq, Klaus Ensslin, Keiji Saito, Yasuhiro Utsumi, and Arthur C. Gossard
We experimentally demonstrate the validity of nonequilibrium fluctuation relations by using a quantum coherent conductor. In equilibrium the fluctuation-dissipation relation leads to the correlation between current and current noise at the conductor, namely, the Johnson-Nyquist relation. When the co...
[Phys. Rev. Lett. 104, 080602] Published Thu Feb 25, 2010
Telecommunication-Wavelength Solid-State Memory at the Single Photon Level
Author(s): Björn Lauritzen, Jiří Minář, Hugues de Riedmatten, Mikael Afzelius, Nicolas Sangouard, Christoph Simon, and Nicolas Gisin
We demonstrate experimentally the storage and retrieval of weak coherent light fields at telecommunication wavelengths in a solid. Light pulses at the single photon level are stored for a time up to 600 ns in an erbium-doped Y2SiO5 crystal at 2.6 K and retrieved on demand. The memory is based on p...
[Phys. Rev. Lett. 104, 080502] Published Wed Feb 24, 2010
Drag Forces in Classical Fields
Author(s): Vincent Démery and David S. Dean
Inclusions, or defects, moving at constant velocity through free classical fields are shown to be subject to a drag force which depends on the field dynamics and the coupling of the inclusion to the field. The results are used to predict the drag exerted on inclusions, such as proteins, in lipid mem...
[Phys. Rev. Lett. 104, 080601] Published Tue Feb 23, 2010
All Reversible Dynamics in Maximally Nonlocal Theories are Trivial
Author(s): David Gross, Markus Müller, Roger Colbeck, and Oscar C. O. Dahlsten
A remarkable feature of quantum theory is nonlocality (Bell inequality violations). However, quantum correlations are not maximally nonlocal, and it is natural to ask whether there are compelling reasons for rejecting theories in which stronger violations are possible. To shed light on this question...
[Phys. Rev. Lett. 104, 080402] Published Tue Feb 23, 2010
Unified View of Quantum and Classical Correlations
Author(s): Kavan Modi, Tomasz Paterek, Wonmin Son, Vlatko Vedral, and Mark Williamson
We discuss the problem of the separation of total correlations in a given quantum state into entanglement, dissonance, and classical correlations using the concept of relative entropy as a distance measure of correlations. This allows us to put all correlations on an equal footing. Entanglement and ...
[Phys. Rev. Lett. 104, 080501] Published Mon Feb 22, 2010
Observation of Elastic Doublon Decay in the Fermi-Hubbard Model
Author(s): Niels Strohmaier, Daniel Greif, Robert Jördens, Leticia Tarruell, Henning Moritz, Tilman Esslinger, Rajdeep Sensarma, David Pekker, Ehud Altman, and Eugene Demler
We investigate the decay of highly excited states of ultracold fermions in a three-dimensional optical lattice. Starting from a repulsive Fermi-Hubbard system near half filling, we generate additional doubly occupied sites (doublons) by lattice modulation. The subsequent relaxation back to thermal e...
[Phys. Rev. Lett. 104, 080401] Published Mon Feb 22, 2010
Predicted Mobility Edges in One-Dimensional Incommensurate Optical Lattices: An Exactly Solvable Model of Anderson Localization
Author(s): J. Biddle and S. Das Sarma
Localization properties of noninteracting quantum particles in one-dimensional incommensurate lattices are investigated with an exponential short-range hopping that is beyond the minimal nearest-neighbor tight-binding model. Energy dependent mobility edges are analytically predicted in this model an...
[Phys. Rev. Lett. 104, 070601] Published Fri Feb 19, 2010
Non-Markovian Quantum Dynamics: Local versus Nonlocal
Author(s): Dariusz Chruściński and Andrzej Kossakowski
We analyze non-Markovian evolution of open quantum systems. It is shown that any dynamical map representing the evolution of such a system may be described either by a nonlocal master equation with a memory kernel or equivalently by an equation which is local in time. These two descriptions are comp...
[Phys. Rev. Lett. 104, 070406] Published Fri Feb 19, 2010
Stable Levitation and Alignment of Compact Objects by Casimir Spring Forces
Author(s): Sahand Jamal Rahi and Saad Zaheer
We investigate a stable Casimir force configuration consisting of an object contained inside a spherical or spheroidal cavity filled with a dielectric medium. The spring constant for displacements from the center of the cavity and the dependence of the energy on the relative orientations of the inne...
[Phys. Rev. Lett. 104, 070405] Published Fri Feb 19, 2010
Universal Scaling Laws for Dispersion Interactions
Author(s): Stefan Yoshi Buhmann, Stefan Scheel, and James Babington
We study the scaling behavior of dispersion potentials and forces under very general conditions. We prove that a rescaling of an arbitrary geometric arrangement by a factor a changes the atom–atom and atom–body potentials in the long-distance limit by factors 1/a7 and 1/a4, respectively, and the...
[Phys. Rev. Lett. 104, 070404] Published Fri Feb 19, 2010
