Superpositions of thermalisations in relativistic quantum field theory

TL;DR

This paper explains why quantum systems in superpositions of accelerated trajectories may fail to thermalise, using relativistic quantum field theory, revealing new insights into quantum thermodynamics and relativistic effects.

Contribution

It provides a relativistic quantum field theory explanation for non-thermalisation in superpositions of accelerated states, connecting quantum information and thermodynamics.

Findings

Superpositions of spatial translations affect thermalisation behavior.

Orthogonal mode cases lead to thermalisation, confirming the explanation.

Relativistic quantum effects can realize quantum thermodynamical scenarios.

Abstract

Recent results in relativistic quantum information and quantum thermodynamics have independently shown that in the quantum regime, a system may fail to thermalise when subject to quantum-controlled application of the same, single thermalisation channel. For example, an accelerating system with fixed proper acceleration is known to thermalise to an acceleration-dependent temperature, known as the Unruh temperature. However, the same system in a superposition of spatially translated trajectories that share the same proper acceleration fails to thermalise. Here, we provide an explanation of these results using the framework of quantum field theory in relativistic noninertial reference frames. We show how a probe that accelerates in a superposition of spatial translations interacts with incommensurate sets of field modes. In special cases where the modes are orthogonal (for example, when the Rindler wedges are translated in a direction orthogonal to the plane of motion), thermalisation does indeed result, corroborating the here provided explanation. We then discuss how this description relates to an information-theoretic approach aimed at studying quantum aspects of temperature through quantum-controlled thermalisations. The present work draws a connection between research in quantum information, relativistic physics, and quantum thermodynamics, in particular showing that relativistic quantum effects can provide a natural realisation of quantum thermodynamical scenarios.