We developed a model of a quantum Otto engine using two coupled two-level atoms.Based on the platform,we show that frequency detuning and the coupling strength induced by dipoledipole interactions can lead to decohere...We developed a model of a quantum Otto engine using two coupled two-level atoms.Based on the platform,we show that frequency detuning and the coupling strength induced by dipoledipole interactions can lead to decoherence by disrupting coherent energy exchange.We focus on fundamental thermodynamic quantities,including heat absorption,release to heat baths,work done and efficiency.It is noteworthy that the interatomic coupling strength and frequency detuning do not merely affect the shape of the work and the efficiency but ultimately govern its quantitative magnitude.In the field of quantum thermodynamics,we have established an upper bound efficiency that is stricter than the Carnot limit.Moreover,our analysis confirms that quantum coherence enables the system to exceed the efficiency threshold of a classical Otto heat engine.The second law of thermodynamics holds all the while.Our results constitute a step forward in the design of conceptually new quantum thermodynamic devices which take advantage of uniquely quantum resources of quantum coherence.展开更多
The quantum effect plays an important role in quantum thermodynamics,and recently the application of an indefinite causal order to quantum thermodynamics has attracted much attention.Based on two trapped ions,we propo...The quantum effect plays an important role in quantum thermodynamics,and recently the application of an indefinite causal order to quantum thermodynamics has attracted much attention.Based on two trapped ions,we propose a scheme to add an indefinite causal order to the isochoric cooling stroke of an Otto engine through reservoir engineering.Then,we observe that the quasi-static efficiency of this heat engine is far beyond the efficiency of a normal Otto heat engine and may reach one.When the power is its maximum,the efficiency is also much higher than that of a normal Otto heat engine.This enhancement may originate from the nonequilibrium of the reservoir and the measurement on the control qubit.展开更多
We propose a quantum Otto engine operating through a cycle of two isochoric processes,where the working substance interacts with a single-mode radiation field,and two unitary strokes,during which the working substance...We propose a quantum Otto engine operating through a cycle of two isochoric processes,where the working substance interacts with a single-mode radiation field,and two unitary strokes,during which the working substance is decoupled from the field.We investigate the influence of quantum superposition and quantum internal friction on the engine's power output and efficiency,demonstrating that these quantum effects enhance both performance metrics.While these enhancements are accompanied by increased power fluctuations,we show that such fluctuations can be effectively mitigated through careful selection of control parameters.Our results reveal that the proposed quantum Otto engine can achieve performance regimes that are thermally inconceivable in classical systems,including surpassing the Otto efficiency limit and attaining 100%efficiency with nonzero power output.展开更多
We consider a quantum endoreversible Otto engine cycle and its inverse operation-Otto refrigeration cycle,employing two-level systems as the working substance and operating in dual-squeezed reservoirs.We demonstrate t...We consider a quantum endoreversible Otto engine cycle and its inverse operation-Otto refrigeration cycle,employing two-level systems as the working substance and operating in dual-squeezed reservoirs.We demonstrate that the efficiency of heat engines at maximum work output and the coefficient of performance for refrigerators at the maximum c criterion will degenerate toη-=η_(C)/(2-η_(C))andε-=(√9+8ε_(C)-3)/2 when symmetric squeezing is satisfied,respectively.We also investigated the influences of squeezing degree on the performance optimization of quantum Otto heat engines at the maximum work output and refrigerators at the maximum X criterion.These analytical results show that the efficiency of heat engines at maximum work output and the coefficient of performance for refrigerators at the maximum X criterion can be improved,reduced or even inhibited in asymmetric squeezing.Furthermore,we also find that the efficiency of quantum Otto heat engines at maximum work output is lower than that obtained from the Otto heat engines based on a single harmonic oscillator system.However,the coefficient of performance of the corresponding refrigerator is higher.展开更多
基金supported by University-Industry Collaborative Education Program(Project No.220506627183928)。
文摘We developed a model of a quantum Otto engine using two coupled two-level atoms.Based on the platform,we show that frequency detuning and the coupling strength induced by dipoledipole interactions can lead to decoherence by disrupting coherent energy exchange.We focus on fundamental thermodynamic quantities,including heat absorption,release to heat baths,work done and efficiency.It is noteworthy that the interatomic coupling strength and frequency detuning do not merely affect the shape of the work and the efficiency but ultimately govern its quantitative magnitude.In the field of quantum thermodynamics,we have established an upper bound efficiency that is stricter than the Carnot limit.Moreover,our analysis confirms that quantum coherence enables the system to exceed the efficiency threshold of a classical Otto heat engine.The second law of thermodynamics holds all the while.Our results constitute a step forward in the design of conceptually new quantum thermodynamic devices which take advantage of uniquely quantum resources of quantum coherence.
基金supported by National Natural Science Foundation of China under Grant No.11965012Yunan Province’s Hi-tech Talents Recruitment Plan No.YNWR-QNBJ-2019-245。
文摘The quantum effect plays an important role in quantum thermodynamics,and recently the application of an indefinite causal order to quantum thermodynamics has attracted much attention.Based on two trapped ions,we propose a scheme to add an indefinite causal order to the isochoric cooling stroke of an Otto engine through reservoir engineering.Then,we observe that the quasi-static efficiency of this heat engine is far beyond the efficiency of a normal Otto heat engine and may reach one.When the power is its maximum,the efficiency is also much higher than that of a normal Otto heat engine.This enhancement may originate from the nonequilibrium of the reservoir and the measurement on the control qubit.
基金supported by the National Natural Science Foundation of China(Grant No.12465009)support from the Major Program of Jiangxi Provincial Natural Science Foundation,China(Grant No.20224ACB201007)。
文摘We propose a quantum Otto engine operating through a cycle of two isochoric processes,where the working substance interacts with a single-mode radiation field,and two unitary strokes,during which the working substance is decoupled from the field.We investigate the influence of quantum superposition and quantum internal friction on the engine's power output and efficiency,demonstrating that these quantum effects enhance both performance metrics.While these enhancements are accompanied by increased power fluctuations,we show that such fluctuations can be effectively mitigated through careful selection of control parameters.Our results reveal that the proposed quantum Otto engine can achieve performance regimes that are thermally inconceivable in classical systems,including surpassing the Otto efficiency limit and attaining 100%efficiency with nonzero power output.
文摘We consider a quantum endoreversible Otto engine cycle and its inverse operation-Otto refrigeration cycle,employing two-level systems as the working substance and operating in dual-squeezed reservoirs.We demonstrate that the efficiency of heat engines at maximum work output and the coefficient of performance for refrigerators at the maximum c criterion will degenerate toη-=η_(C)/(2-η_(C))andε-=(√9+8ε_(C)-3)/2 when symmetric squeezing is satisfied,respectively.We also investigated the influences of squeezing degree on the performance optimization of quantum Otto heat engines at the maximum work output and refrigerators at the maximum X criterion.These analytical results show that the efficiency of heat engines at maximum work output and the coefficient of performance for refrigerators at the maximum X criterion can be improved,reduced or even inhibited in asymmetric squeezing.Furthermore,we also find that the efficiency of quantum Otto heat engines at maximum work output is lower than that obtained from the Otto heat engines based on a single harmonic oscillator system.However,the coefficient of performance of the corresponding refrigerator is higher.
