8 March 2022 Tue 4 pm

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The second law of thermodynamics imposes constraints on thermodynamic quantities. For open quantum systems, the second law is written in terms of the quantum relative entropy, which gives an inequality similar to the second law in classical stochastic systems. Thus the quantum relative entropy cannot exhibit the effect of quantum nature on the limits of thermodynamic quantities. In this presentation, I will discuss that through the quasi-probability distributions description one can obtain novel thermodynamic relations for quantum systems. For a quantum Otto engine consisting of a harmonic oscillator, I derive variants of the second law with respect to each quasi-probability distribution using stochastic thermodynamics. Some relations are more informative than the classical second law as they give thermal efficiency bounds tighter than the Carnot efficiency. The result implies that the quasi-probability description can be a useful tool for exploring the thermodynamic relations in quantum systems. Quantum extensions of recently derived thermodynamic relations, such as the thermodynamic uncertainty relation, are addressed as a future work.

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