Maximum Power Output of Quantum Heat Engine with Energy Bath

TL;DR

This paper investigates the maximum power output of a quantum heat engine operating with an energy bath, analyzing how efficiency and power depend on quantum state control and process parameters.

Contribution

It introduces a quantum heat engine model combining isoenergetic, isothermal, and adiabatic processes, and explores power optimization with finite potential change velocity.

Findings

Power output depends on initial and final states of the isothermal process.

Efficiency and power are optimized by controlling ground state occupation.

The relation between efficiency and power output is analyzed.

Abstract

The difference between quantum isoenergetic process and quantum isothermal process comes from the violation of the law of equipartition of energy in the quantum regime. To reveal an important physical meaning of this fact, here we study a special type of quantum heat engine consisting of three processes: isoenergetic, isothermal and adiabatic processes. Therefore, this engine works between the energy and heat baths. Combining two engines of this kind, it is possible to realize the quantum Carnot engine. Furthermore, considering finite velocity of change of the potential shape, here an infinite square well with moving walls, the power output of the engine is discussed. It is found that the efficiency and power output are both closely dependent on the initial and final states of the quantum isothermal process. The performance of the engine cycle is shown to be optimized by control of the occupation probability of the ground state, which is determined by the temperature and the potential width. The relation between the efficiency and power output is also discussed.