Nonclassicality Phase-Space Functions: More Insight with Fewer Detectors

TL;DR

This paper introduces a method combining on-off detectors with unbalanced homodyning to directly sample phase-space functions, revealing nonclassical effects with fewer detectors and less data processing.

Contribution

It presents a novel technique to visualize nonclassicality using click detectors and unbalanced homodyning, enabling efficient quantum state analysis with minimal detector resources.

Findings

Small number of on-off detectors can reveal nonclassicality.

Sampled phase-space functions show negativities indicating quantum signatures.

Method simplifies nonclassicality detection in quantum optics.

Abstract

Systems of on-off detectors are well established for measuring radiation fields in the regime of small photon numbers. We propose to combine these detector systems with unbalanced homodyning with a weak local oscillator. This approach yields phase-space functions, which represent the click counterpart of the s parametrized quasiprobabilities of standard photoelectric detection theory. This introduced class of distributions can be directly sampled from the measured click counting statistics. Therefore, our technique visualizes nonclassical effects without further data processing. Surprisingly, a small number of on-off diodes can yield more insight than perfect photon number resolution. Quantum signatures in the particle and wave domain of the quantized radiation field, as shown by photon number and squeezed states, respectively, will be uncovered in terms of negativities of the sampled phase-space functions. Application in the vast fields of quantum optics and quantum technology will benefit from our efficient nonclassicality characterization approach.