The gravitational quantum Otto refrigeration cycle

TL;DR

This paper proposes a quantum Otto refrigeration cycle leveraging gravitational redshift effects in curved spacetime, deriving bounds and examples across various gravitational fields, expanding quantum thermodynamics understanding in gravitational contexts.

Contribution

It introduces a novel quantum refrigeration cycle utilizing gravitational redshift and derives bounds for operation in different gravitational fields, including cosmological and astrophysical scenarios.

Findings

Derived a lower bound for the temperature difference in gravitational quantum Otto cycles.

Provided explicit examples in various spacetime geometries.

Extended quantum thermodynamics to curved spacetime environments.

Abstract

We take advantage of the gravitational redshift experienced by a photon propagating in curved spacetime in order to construct a quantum Otto refrigeration cycle. Deriving a lower bound for the relative temperature between the cold and hot reservoirs at which the engine operates, we provide examples of refrigeration cycles in the presence of a uniform gravitational field as well as in the case of a gravitational field produced by a non-rotating spherically symmetric charged body, and the one obtained from the vacuum solution of Einstein's field equations in an expanding universe, as a function of the parameters which describe each spacetime.