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We study two two-level atomic quantum systems (qubits) placed close to a body held at a temperature different from that of the surrounding walls. While at thermal equilibrium the two-qubit dynamics is characterized by not entangled steady…

Quantum Physics · Physics 2015-09-01 Bruno Bellomo , Mauro Antezza

We study the entanglement capability of the evolution of a pair of qubits evolving under unitary dynamics, when the local dynamical parameters cannot be modified during the time-evolution. Unlike the fast local control regime, we find that…

Quantum Physics · Physics 2009-11-13 Raffaele Romano

With bichromatic fields it is possible to deterministically produce entangled states of trapped ions. In this paper we present a unified analysis of this process for both weak and strong fields, for slow and fast gates. Simple expressions…

Quantum Physics · Physics 2009-11-06 Anders Sorensen , Klaus Molmer

We study thermal entanglement in a two-superconducting-qubit system in two cases, either identical or distinct. By calculating the concurrence of system, we find that the entangled degree of the system is greatly enhanced in the case of…

Quantum Physics · Physics 2011-04-14 Li-Jun Tian , Li-Guo Qin , Hong-Biao Zhang

We study the entanglement of a two-qubit one dimensional XYZ Heisenberg chain in thermal equilibrium at temperature T. We obtain an analytical expression for the entanglement of formation for this system in terms of the parameters of the…

Quantum Physics · Physics 2007-05-23 G. Rigolin

We analyze whether a pair of neutral two level atoms can become entangled in a finite time while they remain causally disconnected. The interaction with the e. m. field is treated perturbatively in the electric dipole approximation. We…

Quantum Physics · Physics 2009-11-13 Juan León , Carlos Sabín

How mixed can one component of a bi-partite system be initially and still become entangled through interaction with a thermalized partner? We address this question here. In particular, we consider the question of how mixed a two-level…

Quantum Physics · Physics 2016-11-02 S. Scheel , J. Eisert , P. L. Knight , M. B. Plenio

The maximum entanglement between two coupled qubits in the steady state under two independent incoherent sources of excitation is reported. Asymmetric configurations where one qubit is excited while the other one dissipates the excitation…

Quantum Physics · Physics 2011-01-11 Elena del Valle

Atomic collisions are included in an interacting system of optical fields and trapped atoms allowing field amplification. We study the effects of collisions on the system stability. Also a study of the degree of entanglement between atomic…

Quantum Physics · Physics 2008-06-17 V. V. França , G. A. Prataviera

Introducing classical fields, we can transfer entanglement completely from discrete qubits into entangled coherent state. The entanglement also can be retrieved from the continuous-variable state of the cavities to the atomic qubits. Via…

Quantum Physics · Physics 2009-11-13 Ling Zhou , Guo-Hui Yang

Using the algebraic dynamical method, the dynamics of entanglement in an atom-field bipartite system in a mixed state is investigated. The atomic center-ofmass motion and the field-mode structure are also included in this system. We find…

Quantum Physics · Physics 2010-07-01 Lei Tan , Zhong-Hua Zhu , Yu-Qing Zhang

We explore the role of entanglement in adiabatic quantum optimization by performing approximate simulations of the real-time evolution of a quantum system while limiting the amount of entanglement. To classically simulate the time evolution…

Disordered Systems and Neural Networks · Physics 2015-01-29 Bela Bauer , Lei Wang , Iztok Pižorn , Matthias Troyer

Multiparticle entanglement leads to richer correlations than two-particle entanglement and gives rise to striking contradictions with local realism, inequivalent classes of entanglement, and applications such as one-way or topological…

Quantum Physics · Physics 2010-12-03 J. T. Barreiro , P. Schindler , O. Gühne , T. Monz , M. Chwalla , C. F. Roos , M. Hennrich , R. Blatt

We investigate the thermal entanglement of interacting two qubits. We maximize it by tuning a local Hamiltonian under a given interaction Hamiltonian. We prove that the optimizing local Hamiltonian takes a simple form which dose not depend…

Quantum Physics · Physics 2012-07-13 Tomotaka Kuwahara , Naomichi Hatano

We report an experiment in which one determines, with least tomographic effort, whether an unknown two-photon polarization state is entangled or separable. The method measures whole families of optimal entanglement witnesses. We introduce…

Quantum Physics · Physics 2014-10-29 Jibo Dai , Yink Loong Len , Yong Siah Teo , Berthold-Georg Englert , Leonid A. Krivitsky

In order to assess inelastic effects on two fermion entanglement production, we address an exactly solvable two-particle scattering problem where the target is an excitable scatterer. Useful entanglement, as measured by the two particle…

Quantum Physics · Physics 2009-11-13 A. Lopez , V. M. Villalba , E. Medina

Heralded entanglement between collective excitations in two atomic ensembles is probabilistically generated, stored, and converted to single photon fields. By way of the concurrence, quantitative characterizations are reported for the…

Quantum Physics · Physics 2009-11-13 J. Laurat , K. S. Choi , H. Deng , C. W. Chou , H. J. Kimble

We investigate how the interplay between a staggered magnetic field and staggered coupling strength affects both ground state and thermal entanglement. Upon analytically calculating thermodynamic quantities and the correlation functions for…

Quantum Physics · Physics 2012-06-26 Jenny Hide , Yoshifumi Nakata , Mio Murao

The generation of entanglement between two oscillators that interact via a common reservoir is theoretically studied. The reservoir is modeled by a one-dimensional harmonic crystal initially in thermal equilibrium. Starting from a separable…

Quantum Physics · Physics 2011-09-13 Alexander Wolf , Gabriele De Chiara , Endre Kajari , Eric Lutz , Giovanna Morigi

Establishing quantum entanglement between individual nodes is crucial for building large-scale quantum networks, enabling secure quantum communication, distributed quantum computing, enhanced quantum metrology and fundamental tests of…