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Recently published articles in Phys. Rev. Lett. in the Table of Content section "General Physics: Statistical and Quantum Mechanics, Quantum Information, etc."
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Special Comparison Theorem for the Dirac Equation
Author(s): Richard L. Hall
If a central vector potential V(r,a) in the Dirac equation is monotonic in a parameter a, then a discrete eigenvalue E(a) is monotonic in a. For such a special class of comparisons, this generalizes an earlier comparison theorem that was restricted to node free states. Moreover, the present theorem ...
[Phys. Rev. Lett. 101, 090401] Published Mon Aug 25, 2008
If a central vector potential V(r,a) in the Dirac equation is monotonic in a parameter a, then a discrete eigenvalue E(a) is monotonic in a. For such a special class of comparisons, this generalizes an earlier comparison theorem that was restricted to node free states. Moreover, the present theorem ...
[Phys. Rev. Lett. 101, 090401] Published Mon Aug 25, 2008
Sudden Birth versus Sudden Death of Entanglement in Multipartite Systems
Author(s): C. E. López, G. Romero, F. Lastra, E. Solano, and J. C. Retamal
We study the entanglement dynamics of two cavities interacting with independent reservoirs. Expectedly, as the cavity entanglement is depleted, it is transferred to the reservoir degrees of freedom. We find also that when the cavity entanglement suddenly disappears, the reservoir entanglement sudden...
[Phys. Rev. Lett. 101, 080503] Published Fri Aug 22, 2008
We study the entanglement dynamics of two cavities interacting with independent reservoirs. Expectedly, as the cavity entanglement is depleted, it is transferred to the reservoir degrees of freedom. We find also that when the cavity entanglement suddenly disappears, the reservoir entanglement sudden...
[Phys. Rev. Lett. 101, 080503] Published Fri Aug 22, 2008
Controlling the Spontaneous Emission of a Superconducting Transmon Qubit
Author(s): A. A. Houck, J. A. Schreier, B. R. Johnson, J. M. Chow, Jens Koch, J. M. Gambetta, D. I. Schuster, L. Frunzio, M. H. Devoret, S. M. Girvin, and R. J. Schoelkopf
We present a detailed characterization of coherence in seven transmon qubits in a circuit QED architecture. We find that spontaneous emission rates are strongly influenced by far off-resonant modes of the cavity and can be understood within a semiclassical circuit model. A careful analysis of the sp...
[Phys. Rev. Lett. 101, 080502] Published Thu Aug 21, 2008
We present a detailed characterization of coherence in seven transmon qubits in a circuit QED architecture. We find that spontaneous emission rates are strongly influenced by far off-resonant modes of the cavity and can be understood within a semiclassical circuit model. A careful analysis of the sp...
[Phys. Rev. Lett. 101, 080502] Published Thu Aug 21, 2008
Multistage Entanglement Swapping
Author(s): Alexander M. Goebel, Claudia Wagenknecht, Qiang Zhang, Yu-Ao Chen, Kai Chen, Jörg Schmiedmayer, and Jian-Wei Pan
We report an experimental demonstration of entanglement swapping over two quantum stages. By successful realizations of two cascaded photonic entanglement swapping processes, entanglement is generated and distributed between two photons, that originate from independent sources and do not share any c...
[Phys. Rev. Lett. 101, 080403] Published Thu Aug 21, 2008
We report an experimental demonstration of entanglement swapping over two quantum stages. By successful realizations of two cascaded photonic entanglement swapping processes, entanglement is generated and distributed between two photons, that originate from independent sources and do not share any c...
[Phys. Rev. Lett. 101, 080403] Published Thu Aug 21, 2008
Visualization of Branch Points in PT-Symmetric Waveguides
Author(s): Shachar Klaiman, Uwe Günther, and Nimrod Moiseyev
The visualization of an exceptional point in a PT-symmetric directional coupler (DC) is demonstrated. In such a system the exceptional point can be probed by varying only a single parameter. Using the Rayleigh-Schrödinger perturbation theory we prove that the spectrum of a PT-symmetric Hamiltonian ...
[Phys. Rev. Lett. 101, 080402] Published Thu Aug 21, 2008
The visualization of an exceptional point in a PT-symmetric directional coupler (DC) is demonstrated. In such a system the exceptional point can be probed by varying only a single parameter. Using the Rayleigh-Schrödinger perturbation theory we prove that the spectrum of a PT-symmetric Hamiltonian ...
[Phys. Rev. Lett. 101, 080402] Published Thu Aug 21, 2008
Error Correcting Bell Inequalities
Author(s): Thomas A. Walker, Fiona A. Polack, and Samuel L. Braunstein
Quantum error-correcting codes can protect multipartite quantum states from errors on some limited number of their subsystems (usually qubits). We construct a family of Bell inequalities which inherit this property from the underlying code and exhibit the violation of local realism, without any quan...
[Phys. Rev. Lett. 101, 080501] Published Mon Aug 18, 2008
Quantum error-correcting codes can protect multipartite quantum states from errors on some limited number of their subsystems (usually qubits). We construct a family of Bell inequalities which inherit this property from the underlying code and exhibit the violation of local realism, without any quan...
[Phys. Rev. Lett. 101, 080501] Published Mon Aug 18, 2008
d-Wave Collapse and Explosion of a Dipolar Bose-Einstein Condensate
Author(s): T. Lahaye, J. Metz, B. Fröhlich, T. Koch, M. Meister, A. Griesmaier, T. Pfau, H. Saito, Y. Kawaguchi, and M. Ueda
We investigate the collapse dynamics of a dipolar condensate of ^{52} Cr atoms when the s-wave scattering length characterizing the contact interaction is reduced below a critical value. A complex dynamics, involving an anisotropic, d-wave symmetric explosion of the condensate, is observed. The atom...
[Phys. Rev. Lett. 101, 080401] Published Mon Aug 18, 2008
We investigate the collapse dynamics of a dipolar condensate of ^{52} Cr atoms when the s-wave scattering length characterizing the contact interaction is reduced below a critical value. A complex dynamics, involving an anisotropic, d-wave symmetric explosion of the condensate, is observed. The atom...
[Phys. Rev. Lett. 101, 080401] Published Mon Aug 18, 2008
Quantum Simulation of Many-Body Hamiltonians Using Perturbation Theory with Bounded-Strength Interactions
Author(s): Sergey Bravyi, David P. DiVincenzo, Daniel Loss, and Barbara M. Terhal
We show how to map a given n-qubit target Hamiltonian with bounded-strength k-body interactions onto a simulator Hamiltonian with two-body interactions, such that the ground-state energy of the target and the simulator Hamiltonians are the same up to an extensive error O(ϵn) for arbitrary small ϵ....
[Phys. Rev. Lett. 101, 070503] Published Fri Aug 15, 2008
We show how to map a given n-qubit target Hamiltonian with bounded-strength k-body interactions onto a simulator Hamiltonian with two-body interactions, such that the ground-state energy of the target and the simulator Hamiltonians are the same up to an extensive error O(ϵn) for arbitrary small ϵ....
[Phys. Rev. Lett. 101, 070503] Published Fri Aug 15, 2008
Pulsating Instability of a Bose-Einstein Condensate in an Optical Lattice
Author(s): Uttam Shrestha, Marijan Kostrun, and Juha Javanainen
We find numerically that in the limit of weak atom-atom interactions a Bose-Einstein condensate in an optical lattice may develop a pulsating dynamical instability in which the atoms nearly periodically form a peak in the occupation numbers of the lattice sites, and then return to the unstable initi...
[Phys. Rev. Lett. 101, 070406] Published Fri Aug 15, 2008
We find numerically that in the limit of weak atom-atom interactions a Bose-Einstein condensate in an optical lattice may develop a pulsating dynamical instability in which the atoms nearly periodically form a peak in the occupation numbers of the lattice sites, and then return to the unstable initi...
[Phys. Rev. Lett. 101, 070406] Published Fri Aug 15, 2008
Nonuniqueness of the Phase Shift in Central Scattering due to Monodromy
Author(s): Holger R. Dullin and Holger Waalkens
Scattering at a central potential is completely characterized by the phase shifts which are the differences in phase between outgoing scattered and unscattered partial waves. In this Letter, it is shown that, for 2D scattering at a repulsive central potential, the phase shift cannot be uniquely defi...
[Phys. Rev. Lett. 101, 070405] Published Thu Aug 14, 2008
Scattering at a central potential is completely characterized by the phase shifts which are the differences in phase between outgoing scattered and unscattered partial waves. In this Letter, it is shown that, for 2D scattering at a repulsive central potential, the phase shift cannot be uniquely defi...
[Phys. Rev. Lett. 101, 070405] Published Thu Aug 14, 2008
Realization of a Strongly Interacting Bose-Fermi Mixture from a Two-Component Fermi Gas
Author(s): Yong-il Shin, André Schirotzek, Christian H. Schunck, and Wolfgang Ketterle
We show the emergence of a strongly interacting Bose-Fermi mixture from a two-component Fermi mixture with population imbalance. By analyzing in situ density profiles of ^{6} Li atoms in the BCS-BEC crossover regime, we identify a critical interaction strength, beyond which all minority atoms pair ...
[Phys. Rev. Lett. 101, 070404] Published Thu Aug 14, 2008
We show the emergence of a strongly interacting Bose-Fermi mixture from a two-component Fermi mixture with population imbalance. By analyzing in situ density profiles of ^{6} Li atoms in the BCS-BEC crossover regime, we identify a critical interaction strength, beyond which all minority atoms pair ...
[Phys. Rev. Lett. 101, 070404] Published Thu Aug 14, 2008
Employing Trapped Cold Ions to Verify the Quantum Jarzynski Equality
Author(s): Gerhard Huber, Ferdinand Schmidt-Kaler, Sebastian Deffner, and Eric Lutz
We propose a scheme to investigate the nonequilibrium work distribution of a quantum particle under well controlled transformations of the external potential, exploiting the versatility of a single ion in a segmented linear Paul trap. We describe in detail how the motional quantum state of a single ...
[Phys. Rev. Lett. 101, 070403] Published Thu Aug 14, 2008
We propose a scheme to investigate the nonequilibrium work distribution of a quantum particle under well controlled transformations of the external potential, exploiting the versatility of a single ion in a segmented linear Paul trap. We describe in detail how the motional quantum state of a single ...
[Phys. Rev. Lett. 101, 070403] Published Thu Aug 14, 2008