Experimental Characterization of a Spin Quantum Heat Engine

Peterson, John P. S.; Batalhão, Tiago B.; Herrera, Marcela; Souza, Alexandre M.; Sarthour, R. S.; Oliveira, I. S.; Serra, R. M.

doi:10.1103/physrevlett.123.240601

Cited by 328 publications

(297 citation statements)

References 72 publications

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“…An analytical result of efficiency and power can be obtained at long control time with our general formalism to match the numerical and experimental results in Ref. [58].…”

Section: Discussionmentioning

confidence: 75%

Boosting the performance of quantum Otto heat engines

2019

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To optimize the performance of a heat engine in finite-time cycle, it is important to understand the finite-time effect of thermodynamic processes. Previously, we have shown that extra work is needed to complete a quantum adiabatic process in finite time, and proved that the extra work follows a C/τ 2 scaling for long control time τ . There the oscillating part of the extra work is neglected due to the complex energy-level structure of the particular quantum system. However, such oscillation of the extra work can not be neglected in some quantum systems with simple energy-level structure, e. g. the two-level system or the quantum harmonic oscillator. In this paper, we build the finite-time quantum Otto engine on these simple systems, and find that the oscillating extra work leads to a jagged edge in the constraint relation between the output power and the efficiency. By optimizing the control time of the quantum adiabatic processes, the oscillation in the extra work is utilized to enhance the maximum power and the efficiency. We further design special control schemes with the zero extra work at the specific control time. Compared to the linear control scheme, these special control schemes of the finite-time adiabatic process improve the maximum power and the efficiency of the finite-time Otto engine.

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“…An analytical result of efficiency and power can be obtained at long control time with our general formalism to match the numerical and experimental results in Ref. [58].…”

Section: Discussionmentioning

confidence: 75%

Boosting the performance of quantum Otto heat engines

2019

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“…A quantum heat engine is a cycle with thermodynamic processes, and its working fluid is a quantum system with coherence, entanglement, and discrete energy levels. Due to the development of experimental techniques, it has been realized in various ways [3][4][5][6], and various heat baths have been also considered: Coherent bath was used to exceed the Carnot efficiency, and decoherent one was introduced to find the signature of quantumness [7][8][9]. Squeezed bath [10] also allowed the efficiency to be beyond the Carnot efficiency due to the nonequilibrium resource.…”

Section: Introductionmentioning

confidence: 99%

“…Most recently, it has also been realized with the nuclear magnetic resonance spectrometer [5,6] and its quasistatic efficiency has been beaten in the finite-time mode with a heat bath of effective negative temperatures [5].…”

Section: Introductionmentioning

confidence: 99%

Finite-time quantum Otto engine: Surpassing the quasistatic efficiency due to friction

Lee¹,

Ha²,

Park³

et al. 2020

Phys. Rev. E

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In finite-time quantum heat engines, some work is consumed to drive a working fluid accompanying coherence, which is called 'friction'. To understand the role of friction in quantum thermodynamics, we present a couple of finite-time quantum Otto cycles with two different baths: Agarwal versus Lindbladian. We exactly solve them and compare the performance of the Agarwal engine with that of the Lidbladian one. Particularly, we find remarkable and counterintuitive results that the performance of the Agarwal engine due to friction can be much higher than that in the quasi-static limit with the Otto efficiency, and the power of the Lindbladian engine can be non-zero in the short-time limit. Based on additional numerical calculations of these outcomes, we discuss possible origins of such differences between two engines and reveal them. Our results imply that even with equilibrium bath, a non-equilibrium working fluid brings on the higher performance than what an equilibrium one does.

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“…These systems can be extremely well controlled experimentally [70,71] and have been used in recent experimental implementations of quantum heat engines [3,72]. An alternative route may be spin systems based on nuclear-magnetic resonances or nitrogen-vacancy setups as in the QHE experiments from [73,74]. For future work we envisage to adapt our protocol to autonomous quantum heat engines that do not require external control.…”

Section: Discussionmentioning

confidence: 99%

Quantum magnetometry using two-stroke thermal machines

et al. 2020

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The precise estimation of small parameters is a challenging problem in quantum metrology. Here, we introduce a protocol for accurately measuring weak magnetic fields using a two-level magnetometer, which is coupled to two (hot and cold) thermal baths and operated as a two-stroke quantum thermal machine. Its working substance consists of a two-level system (TLS), generated by an unknown weak magnetic field acting on a qubit, and a second TLS arising due to the application of a known strong and tunable field on another qubit. Depending on this field, the machine may either act as an engine or a refrigerator. Under feasible conditions, determining this transition point allows to reduce the relative error of the measurement of the weak unknown magnetic field by the ratio of the temperatures of the colder bath to the hotter bath.

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Experimental Characterization of a Spin Quantum Heat Engine

Cited by 328 publications

References 72 publications

Boosting the performance of quantum Otto heat engines

Boosting the performance of quantum Otto heat engines

Finite-time quantum Otto engine: Surpassing the quasistatic efficiency due to friction

Quantum magnetometry using two-stroke thermal machines

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