Entropic distinguishability of quantum fields in phase space

TL;DR

This paper introduces a general entropic measure for quantum field uncertainty in phase space, applicable to both bosonic and fermionic fields, with broad implications for quantum state characterization and phase transitions.

Contribution

It develops a unified entropic uncertainty relation for quantum fields using the Husimi Q-distribution, applicable to bosonic and fermionic systems, with diverse practical applications.

Findings

Bounded entropic uncertainty by the uncertainty principle.

Characterized uncertainty surplus via total particle number.

Provided a quantum phase transition interpretation.

Abstract

We present a general way of quantifying the entropic uncertainty of quantum field configurations in phase space in terms of entropic distinguishability with respect to the vacuum. Our approach is based on the functional Husimi $Q$-distribution and a suitably chosen relative entropy, which we show to be non-trivially bounded from above by the uncertainty principle. The resulting relative entropic uncertainty relation is as general as the concept of coherent states and thus holds for quantum fields of bosonic and fermionic type. Its simple form enables diverse applications, among which we present a complete characterization of the uncertainty surplus of arbitrary states in terms of the total particle number for a scalar field and the fermionic description of the Ising model. Moreover, we provide a quantitative interpretation of the role of the uncertainty principle for quantum phase transitions.