Two-level quantum Otto heat engine operating with unit efficiency far from the quasi-static regime under a squeezed reservoir

Assis, Rogério J. de; Sales, José S.; Mendes, Udenys Cabral; Almeida, N. G. de

doi:10.1088/1361-6455/abcfd9

Cited by 14 publications

(8 citation statements)

References 37 publications

(52 reference statements)

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“…which coincides with the efficiency of a quantum Otto heat engine, [109,110] and is independent of the squeezing parameter r h as it depends on the ratio of the frequencies only. The efficiency at maximum work is taken from Eqs.…”

Section: -4mentioning

confidence: 65%

Quantum Stirling heat engine with squeezed thermal reservoir

Papadatos

2023

Chinese Phys. B

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We analyze the performance of a quantum Stirling heat engine (QSHE), using a two level system and the harmonic oscillator as the working medium, that contacts with a squeezed thermal reservoir and a cold reservoir. First, we derive closed-form expressions for the produced work and efficiency which strongly depends on the squeezing parameter $r_h$. Then, we prove that the effect of squeezing heats the working medium to a higher effective temperature which leads to better overall performance. In particular, the efficiency increases with the degree of squeezing surpassing the standard Carnot limit, when the ratio of temperatures of hot and cold reservoir is small. Furthermore, we derive the analytical expressions for the efficiency at maximum work and the maximum produced work in the high and low temperature regime and we find that at extreme temperatures the squeezing parameter $r_h$ does not affect the performance of the QSHE. Finally, the performance of the QSHE depends on the nature of the working medium.

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Section: -4mentioning

confidence: 65%

Quantum Stirling heat engine with squeezed thermal reservoir

Papadatos

2023

Chinese Phys. B

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“…For example, either the efficiency at maximum power or the coefficient of performance can be dramatically enhanced by reservoir squeezing, and it may be larger than the Carnot value with no violation of the second law of thermodynamics. [12,31,[41][42][43][44][45][46][47][48][49][50][51][52] Besides the quantum Otto cycle, the quantum Carnot model in finite time has attracted much interest and produced meaningful results. [41,49,[53][54][55][56][57][58][59][60][61][62] Among them, the special emphasis has been put on the possible universal behavior of efficiency at maximum power in standard quantum heat engines, with the universality the same as that of the Curzon-Ahlborn efficiency.…”

Section: Introductionmentioning

confidence: 99%

Performance optimization on finite-time quantum Carnot engines and refrigerators based on spin-1/2 systems driven by a squeezed reservoir

Liu¹,

He²,

Wang³

2023

Chinese Phys. B

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We investigate the finite-time performance of a quantum endoreversible Carnot engine cycle and its inverse operation-Carnot refrigeration cycle, employing a spin-$1/2$ system as the working substance. The thermal machine is alternatively driven by a hot boson bath of inverse temperature $\beta_h$ and a cold boson bath at inverse temperature $\beta_c(>\beta_h)$. While for engine model the hot bath is constructed to be squeezed, in the refrigeration cycle the cold bath is established to be squeezed, with squeezing parameter $r$. We obtain the analytical expressions both for efficiency and power in heat engines and for coefficient of performance and cooling rate in refrigerators. We find that, in the high-temperature limit, the efficiency at maximum power is bounded by the analytical value, $\eta_+=1-\sqrt{{\rm{sech}}(2r)(1-\eta_C)}$, and the coefficient of performance at the maximum figure of merit is limited by $ \varepsilon_+=\frac{\sqrt{{\rm{sech}}(2r)(1+\varepsilon_C})}{\sqrt{{\rm{sech}}(2r)(1+\varepsilon_C)-\varepsilon_C}}-1$, where $\eta_C=1-\beta_h/\beta_c$ and $\varepsilon_C=\beta_h/(\beta_c-\beta_h)$ are the respective Carnot values of the engines and refrigerators, and $r$ is the squeezing parameter. These analytical results are identical to corresponding those obtained from the Carnot engines based on harmonic systems, indicating that the efficiency at maximum power and coefficient at maximum figure of merit are independent on the working substance.

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“…The accord between quantum mechanics and thermodynamics is yet to fully unfold [ 1 , 2 , 3 ]. Its fundamental implications have inspired numerous proposals for thermal machines based on quantum working media [ 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 ]. Two major issues which are addressed in such proposals are as follows: What are the performance bounds of heat engines working in quantum regime and what are the thermodynamic properties of these quantum systems which control these bounds?…”

Section: Introductionmentioning

confidence: 99%

Quantum Heat Engines with Complex Working Media, Complete Otto Cycles and Heuristics

Johal

Mehta

2021

Entropy

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Quantum thermal machines make use of non-classical thermodynamic resources, one of which include interactions between elements of the quantum working medium. In this paper, we examine the performance of a quasi-static quantum Otto engine based on two spins of arbitrary magnitudes subject to an external magnetic field and coupled via an isotropic Heisenberg exchange interaction. It has been shown earlier that the said interaction provides an enhancement of cycle efficiency, with an upper bound that is tighter than the Carnot efficiency. However, the necessary conditions governing engine performance and the relevant upper bound for efficiency are unknown for the general case of arbitrary spin magnitudes. By analyzing extreme case scenarios, we formulate heuristics to infer the necessary conditions for an engine with uncoupled as well as coupled spin model. These conditions lead us to a connection between performance of quantum heat engines and the notion of majorization. Furthermore, the study of complete Otto cycles inherent in the average cycle also yields interesting insights into the average performance.

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Two-level quantum Otto heat engine operating with unit efficiency far from the quasi-static regime under a squeezed reservoir

Cited by 14 publications

References 37 publications

Quantum Stirling heat engine with squeezed thermal reservoir

Quantum Stirling heat engine with squeezed thermal reservoir

Performance optimization on finite-time quantum Carnot engines and refrigerators based on spin-1/2 systems driven by a squeezed reservoir

Quantum Heat Engines with Complex Working Media, Complete Otto Cycles and Heuristics

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