An autonomous single-piston engine with a quantum rotor

TL;DR

This paper introduces a quantum rotor-based autonomous single-piston engine that operates via a superconducting circuit, implementing a Carnot cycle with standard thermal baths and no external control, demonstrating net positive work extraction.

Contribution

It presents a novel quantum piston engine design using a Josephson flux loop as a quantum rotor, enabling autonomous operation and work extraction without external control.

Findings

Engine can perform a Carnot cycle autonomously.

Net positive work is extracted using a filter cavity as a valve.

Implementation feasible with circuit quantum electrodynamics.

Abstract

Pistons are elementary components of a wide variety of thermal engines, allowing to convert input fuel into rotational motion. Here, we propose a single-piston engine where the rotational degree of freedom is effectively realized by the flux of a Josephson loop -- a quantum rotor -- while the working volume corresponds to the effective length of a superconducting resonator. Our autonomous design implements a Carnot cycle, relies solely on standard thermal baths and can be implemented with circuit quantum electrodynamics. We demonstrate how the engine is able to extract a net positive work via its built-in synchronicity using a filter cavity as an effective valve, eliminating the need for external control.