Negative Full Counting Statistics Arise From Interference Effects

TL;DR

This paper links negative full counting statistics in quantum systems to interference effects in Hilbert space trajectories, providing a clearer understanding of their origin and potential experimental detection.

Contribution

It introduces a trajectory-based interpretation of full counting statistics, connecting negativity to interference effects, and demonstrates this with energy fluctuations in a driven bosonic resonator.

Findings

Negative quasi-probabilities are linked to interference effects.

Energy fluctuations in a driven bosonic resonator can exhibit negativity.

Potential for experimental detection using superconducting microwave circuits.

Abstract

The Keldysh-ordered full counting statistics is a quasi-probability distribution describing the fluctuations of a time-integrated quantum observable. While it is well known that this distribution can fail to be positive, the interpretation and origin of this negativity has been somewhat unclear. Here, we show how the full counting statistics can be tied to trajectories through Hilbert space, and how this directly connects negative quasi-probabilities to an unusual interference effect. Our findings are illustrated with the example of energy fluctuations in a driven bosonic resonator; we discuss how negative quasi-probability here could be detected experimentally using superconducting microwave circuits.