Statistical properties of quantum jumps between macroscopic states of light: reading an operational coherence record

TL;DR

This paper proposes an experimental method to analyze quantum coherence in macroscopic light states through statistical analysis of quantum jumps, revealing insights into quantum state dynamics and coherence properties.

Contribution

It introduces a novel experimental setup that links quantum jump statistics to the phase-space representations of macroscopic quantum states.

Findings

Charge distribution converges to the Q function or Wigner function marginals.

Statistical properties of jumps relate to cavity field correlations.

Method reveals coherence in quantum jumps of macroscopic light states.

Abstract

We propose an experimental apparatus to reveal the quantum coherence manifested in downward quantum jumps of amplitude bistability. The underlying coherent superposition of macroscopic quantum states is translated into the statistical properties of the integrated charge deposited in the detector circuit of a mode-matched heterodyne/homodyne detection scheme. At first, the dynamical evolution of a signal transmitted from an auxiliary cavity is employed to pinpoint a macroscopic switching event in a bistable main cavity subject to direct photodetection. Once the decision is made on the occurrence of a downward switch, the main cavity mode is let to freely decay to the vacuum, monitored to the production of an integrated charge. In the long-time limit, the charge distribution over an identical collection of pure states generated during the jumps converges to the Q function (heterodyne detection) or marginals of the Wigner function (homodyne detection) dictated by the phase of the local oscillator. When fluctuations over the ensemble step in, we connect the statistical properties of several switching events and the ensuing production of current records, to the cavity field correlations associated with the breakdown of photon blockade.