Presence of quantum correlations results in a nonvanishing ergotropic gap

Mukherjee, Amit; Roy, Arup; Bhattacharya, Some Sankar; Banik, Manik

doi:10.1103/physreve.93.052140

Cited by 27 publications

(23 citation statements)

References 48 publications

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“…The study of thermodynamics in quantum domain can be approached from different directions such as information-theoretic point of view [5][6][7][8][9][10] or resource-theoretic aspect [11][12][13]. Another important constituent, in this area of study, is the work extraction from quantum systems [14][15][16][17][18]. Besides these, analyzing different models of thermodynamic machines in the quantum domain can also provide new insight.…”

Section: Introductionmentioning

confidence: 99%

Implications of Coupling in Quantum Thermodynamic Machines

Thomas

Banik

Ghosh

2017

Entropy

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Abstract:We study coupled quantum systems as the working media of thermodynamic machines. Under a suitable phase-space transformation, the coupled systems can be expressed as a composition of independent subsystems. We find that for the coupled systems, the figures of merit, that is the efficiency for engine and the coefficient of performance for refrigerator, are bounded (both from above and from below) by the corresponding figures of merit of the independent subsystems. We also show that the optimum work extractable from a coupled system is upper bounded by the optimum work obtained from the uncoupled system, thereby showing that the quantum correlations do not help in optimal work extraction. Further, we study two explicit examples; coupled spin-1/2 systems and coupled quantum oscillators with analogous interactions. Interestingly, for particular kind of interactions, the efficiency of the coupled oscillators outperforms that of the coupled spin-1/2 systems when they work as heat engines. However, for the same interaction, the coefficient of performance behaves in a reverse manner, while the systems work as the refrigerator. Thus, the same coupling can cause opposite effects in the figures of merit of heat engine and refrigerator.

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Section: Introductionmentioning

confidence: 99%

Implications of Coupling in Quantum Thermodynamic Machines

Thomas

Banik

Ghosh

2017

Entropy

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“…Ergotropic gap for pure product states vanish, due to the fact that any pure state can be transformed to |0 under unitary operation. However, in general for product states the situation is different, depending upon individual Hamiltonian [16], where the ergotropic gap can be nonzero, even with vanishing local ergotropy. It is obvious that for several entangled or classically correlated states this gap is non-vanishing.…”

Section: B Correlation and Ergotropic Gapmentioning

confidence: 99%

“…Although, the advantage of quantum entanglement is well explored in numerous information theoretic and computational tasks [5][6][7][8][9], the power of this correlation has recently been studied in various work extraction protocols from the thermodynamic perspective [10][11][12][13][14][15][16][17][18][19]. This motivates us to specify the following task: Consider a bipartite quantum system governed by the local linear spaced Hamiltonian.…”

Section: Introductionmentioning

confidence: 99%

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Bound on ergotropic gap for bipartite separable states

2019

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Presence of correlations among the constituent quantum systems has a great relevance in thermodynamics. Significant efforts have been devoted to investigate the role of correlations in work extraction, among others. Here, we derive a bound on the difference between global and local extractable work by unitary operations (ergotropic gap), for bipartite separable states. Violation of this bound necessarily certifies the presence of entanglement. This gap is shown to be a monotone under LOCC assisted state transformations for pure bipartite quantum states. Our criterion has an implication in witnessing the dimension of a bipartite quantum state, with same local dimensions. On the other hand, our result gives an operational meaning to the Nielsen-Kempe disorder criterion. We also propose a schematic model to realize the separability bound experimentally and to detect entanglement for a restricted class of quantum states.

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“…One can significantly enhance the extraction of work by exploiting these correlations under the action of a global unitary. Such kind of advantage is primarily exhibited in [13] for the case of degenerate Hamiltonian and subsequently studied in [14][15][16]. Due to a well-established resource theory for quantum thermodynamics [1], it is interesting to quantify the cost of creating such correlations, given some copies of free states.…”

Section: Introductionmentioning

confidence: 99%

Allowed and forbidden bipartite correlations from thermal states

2019

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The strong connection between correlations and quantum thermodynamics raises a natural question about the preparation of correlated quantum states from two copies of a thermal qubit. In this work we study the specific forms of allowed and forbidden bipartite correlations. As a consequence, we extend the result to Separable (SEP) but not Absolutely Separable (AbSEP) class of product states. Preparation of a general form of entanglement from arbitrary thermal qubits is studied and as an application we propose a strategy to establish sustained entanglement between two distant parties. The threshold temperature to produce entanglement from two copies of a thermal qubit has also been discussed from the resource theoretic perspective, which ensures that the bound on the temperature can be superseded with the help of a resource state. A dimension dependent upper-bound on the temperature is derived, below which two copies of any d−dimensional thermal state can be entangled in 2 × d dimension.

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Presence of quantum correlations results in a nonvanishing ergotropic gap

Cited by 27 publications

References 48 publications

Implications of Coupling in Quantum Thermodynamic Machines

Implications of Coupling in Quantum Thermodynamic Machines

Bound on ergotropic gap for bipartite separable states

Allowed and forbidden bipartite correlations from thermal states

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