Quantum thermodynamic cycles and quantum heat engines

Quan, H. T.; Liu, Yu-xi; Sun, C. P.; Nori, Franco

doi:10.1103/physreve.76.031105

Cited by 778 publications

(832 citation statements)

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“…When the working medium of the Otto cycle is classical ideal gas, the efficiency of the system is written as η = 1 − (V 1 /V 2 ) γ−1 , where V 1 and V 2 are initial and final volumes (V 1 < V 2 ) of the adiabatic expansion process and γ = C p /C v , is the ratio of the specific heats [33]. Similar to the classical cycle, the quantum Otto cycle consists of two adiabatic processes and two thermalization processes [34,35]. The system exchanges heat with the bath during the thermalization processes and the work is done when the system undergoes adiabatic processes.…”

Section: Quantum Otto Cyclementioning

confidence: 99%

“…Otto cycle with a single harmonic oscillator (or a spin system) constituting the working medium of the engine is studied in different works [27,30,34,35,38,39]. Here we briefly review this.…”

Section: Single System As a Heat Enginementioning

confidence: 99%

“…Therefore, the isothermal process of the total system can be considered equivalent to the isothermal processes of two independent subsystems taken together. To understand the generality of the bounds of the efficiency observed in Otto cycle, we can consider other cycles such as Carnot cycle consisting of two isothermal processes and two adiabatic processes, and Stirling cycle consisting of two isothermal processes and two isochoric processes [35,39,44] (see Figure 3). Like the Otto cycle, in the Stirling cycle, the global efficiency is bounded by the efficiencies of independent subsystems because at any stage of the cycle, the total system can be decomposed into two independent subsystems.…”

Section: Generalizationmentioning

confidence: 99%

“…Hence the efficiency of the total system lies below the efficiency of oscillator A. Now we can compare the performance in terms of work given in Equations (29) and (35). The terms on the right-hand side of these equations are positive when both the independent systems work in the engine mode.…”

Section: Modelmentioning

confidence: 99%

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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: Quantum Otto Cyclementioning

confidence: 99%

Section: Single System As a Heat Enginementioning

confidence: 99%

Section: Generalizationmentioning

confidence: 99%

Section: Modelmentioning

confidence: 99%

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Implications of Coupling in Quantum Thermodynamic Machines

Thomas

Banik

Ghosh

2017

Entropy

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“…Quantum heat engines are typically based on implementations of quantum Carnot, Otto [15], Brayton [16,17], Diesel [16,18] or Stirling cycles [19,20], with a succession of strokes that alternatively extract work and exchange heat with the hot and cold reservoirs. As a result the generation of work is an intermittent process.…”

Section: Introductionmentioning

confidence: 99%

Deep-subwavelength lithography via graphene plasmons

2017

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We propose a realization of a quantum heat engine in a hybrid microwave-optomechanical system that is the analog of a classical straight-twin engine. It exploits a pair of polariton modes that operate as out-of-phase quantum Otto cycles. A third polariton mode that is essential in the coupling of the optical and microwave fields is maintained in a quasi-dark mode to suppress disturbances from the mechanical noise. We also find that the fluctuations in the contributions to the total work from the two polariton modes are characterized by quantum correlations that generally lead to a reduction in the extractable work compared to its classical version.

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Quantum Heat Engines with Spin‐Chain‐Star Systems

Alsulami,

Abd‐Rabbou

2024

Annalen der Physik

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This study investigates a theoretical model of a Quantum Otto Cycle (QOC) that utilizes a working fluid spin‐chain‐star model. The system consists of a central atom interacting with multiple Heisenberg spin chains. Employing unitary transformations, the spin‐chain‐star system is transformed into a spin‐star model. The work done and heat transferred for three distinct working fluid configurations: the , , and cases are discussed. The efficiency of the heat engine is examined, and a comparative study between the efficiencies of the three configurations is presented. The study assumes two interaction scenarios for the central atom: either with a single chain (resulting in a two‐qubit system after transformation) or with three Heisenberg chains. The results demonstrate that increasing the ratio between the central atom's frequency in the hot bath and the cold bath leads to an enhancement in positive work performed for the and cases. In the case, the magnitude of this enhancement exhibits a dependence on the system's temperature. The QOC employing the configuration working fluid exhibits superior efficiency compared to the other two configurations. Moreover, increasing the central atom's relative frequency improves efficiency for all three cases.

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Quantum thermodynamic cycles and quantum heat engines

Cited by 778 publications

References 50 publications

Implications of Coupling in Quantum Thermodynamic Machines

Implications of Coupling in Quantum Thermodynamic Machines

Deep-subwavelength lithography via graphene plasmons

Quantum Heat Engines with Spin‐Chain‐Star Systems

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