Work Extraction from a Controlled Quantum Emitter

TL;DR

This paper explores how external control fields influence the amount of work that can be extracted from a quantum two-level system interacting with a photonic environment, analyzing different driving protocols and system parameters.

Contribution

It provides a systematic analysis of ergotropy evolution under continuous and pulsed driving, highlighting the effects of detuning and initial states on work extraction in quantum systems.

Findings

Detuning has minimal effect under periodic pulse driving.

Ergotropy increases with detuning in steady state under continuous driving.

Coherent and incoherent contributions to ergotropy are quantified.

Abstract

We investigate how an external driving field can control the amount of extractable work from a quantum emitter, a two-level quantum system (TLS) interacting with a photonic environment. In this scenario, the TLS functions as a quantum battery, interacting with the photonic bath that discharges it while the control field recharges it. Ergotropy serves as our measure of the extractable work from the quantum system. We systematically analyze how the ergotropy of the system evolves as it interacts with the photonic bath under the control of either a continuous driving field or a periodic pulse sequence. The coherent and incoherent contributions to the total ergotropy for various initial states are calculated. The role of detuning between the driving field and the emission frequency of the TLS, as well as the initial state of the system in work extraction, are investigated for continuous and periodic pulse-driving fields. We show that detuning has little impact on work extraction for a system that is driven by a periodic sequence of instantaneous pulses. However, for a continuously driven system, as the system approaches its steady state, ergotropy increases with detuning increases.