Noise in Bose Josephson junctions: Decoherence and phase relaxation

Ferrini, Giulia; Spehner, Dominique; Minguzzi, Anna; Hekking, F. W. J.

doi:10.1103/physreva.82.033621

Cited by 45 publications

(55 citation statements)

References 32 publications

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“…For large enough particle numbers, the two-site Hubbard Hamiltonian can be approximated by the Josephson Hamiltonian [6], which is the reason for these systems to be called Bose Josephson Junctions. A BEC in a double-well potential defines a representation of the rotation group and hence a pseudospin, which can be utilized for quantum information processing and studies of decoherence [7]. Other applications exploit the regime of weak tunneling, where the system behaves similarly to a quantum nanostructure in the sequential tunneling limit [8,9].…”

Section: Introductionmentioning

confidence: 99%

Effects of a single fermion in a Bose Josephson junction

Rinck

Bruder

2011

Phys. Rev. A

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We consider the tunneling properties of a single fermionic impurity immersed in a Bose-Einstein condensate in a double-well potential. For strong boson-fermion interaction, we show the existence of a tunnel resonance where a large number of bosons and the fermion tunnel simultaneously. We give analytical expressions for the line shape of the resonance using degenerate Brillouin-Wigner theory. We finally compute the time-dependent dynamics of the mixture. Using the fermionic tunnel resonances as a beam splitter for wave functions, we construct a Mach-Zehnder interferometer that allows complete population transfer from one well to the other by tilting the double-well potential and only taking into account the fermion's tunnel properties.

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Section: Introductionmentioning

confidence: 99%

Effects of a single fermion in a Bose Josephson junction

Rinck

Bruder

2011

Phys. Rev. A

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“…However, in one dimensional extended systems the Josephson model underlying the physics studied here appears quite naturally as the impurity splits the BEC in two and we would expect there to be connections [76,77]. We also point out that there are many other aspects to the impurity model and its close relatives beyond those discussed here, including how the coherence of the bosons is affected by the impurity [17,78,79], and system-bath dynamics [80][81][82][83]. …”

Section: Summary and Discussionmentioning

confidence: 64%

Critical exponents for an impurity in a bosonic Josephson junction: Position measurement as a phase transition

Mumford

O’Dell

2014

Phys. Rev. A

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We use fidelity susceptibility to calculate quantum critical scaling exponents for a system consisting of N identical bosons interacting with a single impurity atom in a double well potential (bosonic Josephson junction). Above a critical value of the boson-impurity interaction energy there is a spontaneous breaking of Z2 symmetry corresponding to a second order quantum phase transition from a balanced to an imbalanced number of particles in either the left or right hand well. We show that the exponents match those in the Lipkin-Meshkov-Glick and Dicke models suggesting that the impurity model is in the same universality class. The phase transition can be interpreted as a measurement of the position of the impurity by the bosons.

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“…We now focus on dephasing [58,59,18], where the Lindblad operators are the local number operators A j = a † j a j , and the coherences between the Fock states are damped. A realization of such noise is the fluctuation of the depth of the wells, representing the modes, in an optical lattice.…”

Section: Dephasingmentioning

confidence: 99%

Entanglement in dissipative dynamics of identical particles

Marzolino¹

2013

EPL

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Entanglement of identical massive particles recently gained attention, because of its relevance in highly controllable systems, e.g. ultracold gases. It accounts for correlations among modes instead of particles, providing a different paradigm for quantum information. We prove that the entanglement of almost all states rarely vanishes in the presence of noise, and analyse the most relevant noise in ultracold gases: dephasing and particle losses. Furthermore, when the particle number increases, the entanglement decay can turn from exponential into algebraic.Quantum correlations were proved to be a key resource in quantum information processing [1, 2, 3] and a useful tool for studying condensed matter systems [4,5]. Many of these studies were developed in the framework of distinguishable particles, where particles are manipulated locally. The peculiarity of identical particles is that they cannot be individually addressed, unless particles are effectively distinguished employing additional degrees of freedom [6,7,8], e.g. confining them in different positions.The behaviour of truly identical particles is of practical importance, since they are the elementary constituents of several physical systems in atomic and condensed matter physics. For instance, ultracold gases [9,10,11,12] can be controlled with a very high precision, and are a promising arena for the study of many-body physics and applications in quantum information [13,14,15,16,17,18]. However, these systems are unavoidably affected by noise, typically dephasing and particle losses [9].Despite different approaches [19,20,21,22,8], only a few of them are relevant for observable predictions. The characterization of quantum correlations with identical particles cannot rely on the tensor product structure of single particle Hilbert spaces, but must be reformulated in terms of subsets of locally manipulable observables [23,24,25,26,16,27,28]. This powerful approach generalizes the theory of entanglement of distinguishable particles. Moreover, when applied to identical particles, it accounts for quantum correlations of occupations of orthogonal modes, like wells in optical lattices or hyperfine levels of molecules, which are individually addressable in actual experiments [29,30,31].Within this framework, we shall prove that entanglement of almost all the states is never completely dissipated by noise under minimal assumptions including any Markovian noise, contrary to the case of distinguishable particles. Moreover, entanglement is easily generated by tunneling even in the presence of noise. We shall show with concrete examples that entanglement can decay exponentially in time but is never lost. Interestingly, when the number of particles is very large the exponential decay can turn into an algebraic decay.Beyond the characterization of the dynamics itself, the non-vanishing entanglement of many replicas of states discussed here, though small, can be distilled into a fewer copies of more entagled states via local operations and classical communiation, w...

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Noise in Bose Josephson junctions: Decoherence and phase relaxation

Cited by 45 publications

References 32 publications

Effects of a single fermion in a Bose Josephson junction

Effects of a single fermion in a Bose Josephson junction

Critical exponents for an impurity in a bosonic Josephson junction: Position measurement as a phase transition

Entanglement in dissipative dynamics of identical particles

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