Quantum Flywheel

TL;DR

This paper explores the use of quantum monitoring and feedback control to stabilize and optimize the charging efficiency of a quantum harmonic oscillator flywheel powered by a quantum heat engine, balancing information gain and feedback.

Contribution

It introduces a method to stabilize a quantum flywheel using measurement and feedback, enhancing charging efficiency in the presence of quantum and thermal fluctuations.

Findings

Quantum monitoring improves flywheel stability.

Feedback control maximizes charging efficiency.

Steady-state operation achieved through stochastic master equations.

Abstract

A quantum flywheel is studied with the purpose of storing useful work in quantum levels, while additional power is extracted continuously from the device. The flywheel gains its energy form a quantum heat engine. Generally, when a work repository is quantized the work exchange with the engine is accompanied with heat exchange, which may degrade the charging efficiency. In the particular realization of a quantum harmonic oscillator work repository, quantum and thermal fluctuations dominates the dynamics. Quantum monitoring and feedback control are applied to the flywheel, as it is shown to be an essential part of stabilizing and regulating its state of operation, and bringing the system to a steady state. A particular balance between information gained by measuring the system and the information fed back to the system is found to maximize the charging efficiency. The dynamics of the flywheel are described by a stochastic master equation that accounts for the engine, the external driving, the measurement, and the feedback operations.