Entropy and Correlators in Quantum Field Theory

TL;DR

This paper proposes an approach to decoherence in quantum field theory based on neglecting inaccessible correlators, linking information loss to entropy increase, and demonstrates this with Gaussian and non-Gaussian states.

Contribution

It introduces a systematic method to implement renormalisation in quantum field theory through correlator neglect, connecting it to entropy increase and decoherence.

Findings

Calculated entropy of general Gaussian states

Derived entropy corrections for specific non-Gaussian states

Linked information accessibility to entropy changes

Abstract

It is well known that loss of information about a system, for some observer, leads to an increase in entropy as perceived by this observer. We use this to propose an alternative approach to decoherence in quantum field theory in which the machinery of renormalisation can systematically be implemented: neglecting observationally inaccessible correlators will give rise to an increase in entropy of the system. As an example we calculate the entropy of a general Gaussian state and, assuming the observer's ability to probe this information experimentally, we also calculate the correction to the Gaussian entropy for two specific non-Gaussian states.