Spin-mechanical thermal machines

TL;DR

This paper presents a novel method to create a quantum battery and Otto heat engine using an NV center spin coupled to a mechanical oscillator, enabling efficient energy exchange and practical quantum thermal machines.

Contribution

It introduces a new approach for constructing quantum thermal devices with highly detuned NV spin-mechanical systems, demonstrating efficient energy exchange and work production.

Findings

Robust mechanical quantum battery achieved.

Efficient cooling of the oscillator to ground state.

Quantum Otto engine operates at maximum efficiency.

Abstract

We introduce a method to construct a quantum battery and a quantum Otto heat engine using a Nitrogen-Vacancy (NV) center spin coupled to a mechanical oscillator in a highly detuned regime. By precisely controlling the NV spin, we enable efficient energy exchange despite significant detuning, challenging conventional assumptions. This leads to a robust mechanical quantum battery and a cooling scheme driving the oscillator toward its ground state. Leveraging this, we implement a quantum Otto engine that produces mechanical work at maximum efficiency without decoupling from the hot bath, paving the way for practical quantum thermal machines.