Negentropy as a source of efficiency: a nonequilibrium quantum Otto cycle

Li, Hai; Zou, Jian; Yu, Wen-Li; Li, Lin; Xu, Bao-Ming; Shao, Bin

doi:10.1140/epjd/e2013-30763-8

Cited by 16 publications

(11 citation statements)

References 52 publications

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“…along with the normalization condition Equation (24). The integral of Equation (36) from B γ → B δ yields:…”

Section: The Iso-energetic Cyclementioning

confidence: 99%

“…with p 2 (B) = 1 − p 1 (B) after the normalization condition Equation (24). The heat exchanged by the system with the environment during the iso-energetic trajectory connecting the initial and final states B 1 → B 2 is given by the expression:…”

Section: The Iso-energetic Cyclementioning

confidence: 99%

“…Moreover, it has been recently proposed that if the reservoirs are also of a quantum mechanical nature, these could be prepared into quantum coherent states [11,12] or into squeezed thermal states [11,12,22]. These examples by no means constitute the only possible configurations, since a number of different designs based on alternative principles have been proposed in the literature, such as entangled states in a qubit [23] and quantum mechanical versions of the Diesel [15] and the Otto cycle [16,22,24,25]. Conceptually, a statistical ensemble of confined single-particle systems can undergo a cycle of reversible transformations driven by a generalized external field.…”

Section: Introductionmentioning

confidence: 99%

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Magnetically-Driven Quantum Heat Engines: The Quasi-Static Limit of Their Efficiency

Muñoz

Peña

González

2016

Entropy

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Abstract:The concept of a quantum heat engine (QHEN) has been discussed in the literature, not only due to its intrinsic scientific interest, but also as an alternative to efficiently recover, on a nanoscale device, thermal energy in the form of useful work. The quantum character of a QHEN relies, for instance, on the fact that any of its intermediate states is determined by a density matrix operator. In particular, this matrix can represent a mixed state. For a classical heat engine, a theoretical upper bound for its efficiency is obtained by analyzing its quasi-static operation along a cycle drawn by a sequence of quasi-equilibrium states. A similar analysis can be carried out for a quantum engine, where quasi-static processes are driven by the evolution of ensemble-averaged observables, via variation of the corresponding operators or of the density matrix itself on a tunable physical parameter. We recently proposed two new conceptual designs for a magnetically-driven quantum engine, where the tunable parameter is the intensity of an external magnetic field. Along this article, we shall present the general quantum thermodynamics formalism developed in order to analyze this type of QHEN, and moreover, we shall apply it to describe the theoretical efficiency of two different practical implementations of this concept: an array of semiconductor quantum dots and an ensemble of graphene flakes submitted to mechanical tension.

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“…along with the normalization condition Equation (24). The integral of Equation (36) from B γ → B δ yields:…”

Section: The Iso-energetic Cyclementioning

confidence: 99%

Section: The Iso-energetic Cyclementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Magnetically-Driven Quantum Heat Engines: The Quasi-Static Limit of Their Efficiency

Muñoz

Peña

González

2016

Entropy

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“…Phaseonium engine could work with a single heat bath and a phaseonium reservoir [4][5][6][7]. This proposal stimulated much interest to quantum heat engines [8][9][10][11][12][13][14][15][16][17][18][19][20]. It was later argued that existing resonator systems can not implement such an engine, due to high cavity losses and atomic dephasing [21].…”

Section: Introductionmentioning

confidence: 99%

Quantum fuel with multilevel atomic coherence for ultrahigh specific work in a photonic Carnot engine

Türkpençe

Müstecaplıoğlu

2016

Phys. Rev. E

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We investigate scaling of work and efficiency of a photonic Carnot engine with the number of quantum coherent resources. Specifically, we consider a generalization of the "phaseonium fuel" for the photonic Carnot engine, which was first introduced as a three-level atom with two lower states in a quantum coherent superposition by [M. O. Scully, M. Suhail Zubairy, G. S. Agarwal, and H. Walther, Science 299, 862 (2003)], to the case of N + 1 level atoms with N coherent lower levels. We take into account atomic relaxation and dephasing as well as the cavity loss and derive a coarse grained master equation to evaluate the work and efficiency, analytically. Analytical results are verified by microscopic numerical examination of the thermalization dynamics. We find that efficiency and work scale quadratically with the number of quantum coherent levels. Quantum coherence boost to the specific energy (work output per unit mass of the resource) is a profound fundamental difference of quantum fuel from classical resources. We consider typical modern resonator set ups and conclude that multilevel phaseonium fuel can be utilized to overcome the decoherence in available systems. Preparation of the atomic coherences and the associated cost of coherence are analyzed and the engine operation within the bounds of the second law is verified. Our results bring the photonic Carnot engines much closer to the capabilities of current resonator technologies.

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“…These include entangled states in a qubit, 10 as well as quantum mechanical versions of the diesel 6 and Otto cycles (i.e., the operating principles of dieselfueled and gasoline-fueled car engines, respectively). 7,[11][12][13] In general, idealized reciprocating QHENs involve a stationary limit cycle 3,14 consisting of a sequence of intermediate equilibrium states that can be described microscopically by a density matrix operator that depends on a minimal set of macroscopic variables. 14,15 As part of these developments, we have recently proposed a magnetically driven QHEN that combines the effects of a parabolic confining potential (which can be provided by a semiconductor quantum dot) with an external magnetic field.…”

mentioning

confidence: 99%