Alladi Ramakrishnan Hall

Two models of quantum heat engines

George Thomas

IMSc

Quantum heat engines play a crucial role in understanding thermodynamic features of quantum systems. In this talk, I will discuss two models of heat engines. In the first model [1], we study a Stirling engine which extracts work using quantized energy levels. We show that the lack of information about the position of the particle inside the potential well can be converted into useful work without
resorting to any measurement. We show that the Carnot efficiency can be achieved in the low-temperature limit. Further, in the low-temperature limit, we estimate the amount of work extractable from
distinguishable particles, fermions and bosons. In the second model [2], we show that non-Markovian effects of the reservoirs can be used as a resource to extract work from an Otto cycle. We consider a class of non-Markovian dynamics for which the equilibrium state is not an invariant state [3,4]. We show an apparent violation of the second law of thermodynamics unless the cost of non-Markovian effects is considered. We also discuss the cost of non-Markovianity in terms of extractable work. After subtracting the minimum cost for the non-Markovianity, the Otto cycle becomes equivalent to a Carnot cycle. We illustrate our ideas with a specific example of non-Markovian evolution.

[1] G. Thomas, D. Das and S. Ghosh, Quantum heat engine using energy
quantization and resources of ignorance, arXiv: 1802.07681[quant-ph](2018).

[2] G. Thomas, N. Siddharth S. Banerjee and S. Ghosh, Thermodynamics
of non-Markovian reservoirs and heat engines, arXiv:1801.00744 [quant-ph] (2018).

[3] D. Chruscinski, A. Kossakowski, and S. Pascazio, Phys. Rev. A 81, 032101 (2010).

[4] S. Marcantoni, S. Alipour, F. Benatti, R. Floreanini, and A. T. Rezakhani, Sci. Rep. 7, 12447 (2017).