Influence of Indefinite Causal Order on Otto Heat Engine

Quantum effect plays important roles in quantum thermodynamics, and recently the application of indefinite causal order to quantum thermodynamics has attracted much attentions. Based on two trapped ions, we propose a scheme to add an indefinite causal order to the isochoric cooling stroke of 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 1. When the power is its maximum, the efficiency is also much higher than that of a normal Otto heat engine. This enhancement may origin from the non-equilibrium of reservoir and the measurement on control qubit.

Quantum thermodynamics in the no-measurement scheme: driven two-level atom and harmonic oscillator

The two-point measurement and no-measurement schemes are reviewed briefly. The quantum thermodynamics of a driven harmonic oscillator and a two-level atom in an external light field are investigated in the framework of the no-measurement scheme. The work distribution functions and the modified quantum Jarzynski theorem are obtained and discussed.

Hidden Dynamical Symmetry and Quantum Thermodynamics from the First Principles: Quantized Small Environment

Evolution of a self-consistent joint system (JS), i.e., a quantum system (QS) + thermal bath (TB), is considered within the framework of the Langevin–Schrödinger (L-Sch) type equation. As a tested QS, we considered two linearly coupled quantum oscillators that interact with TB. The influence of TB on QS is described by the white noise type autocorrelation function. Using the reference differential equation, the original L-Sch equation is reduced to an autonomous form on a random space–time continuum, which reflects the fact of the existence of a hidden symmetry of JS. It is proven that, as a result of JS relaxation, a two-dimensional quantized small environment is formed, which is an integral part of QS. The possibility of constructing quantum thermodynamics from the first principles of non-Hermitian quantum mechanics without using any additional axioms has been proven. A numerical algorithm has been developed for modeling various properties and parameters of the QS and its environment.