# Detector-Agnostic Phase-Space Distributions

## TL;DR

This paper introduces a detector-agnostic method for reconstructing quantum phase-space distributions, allowing characterization of light states without detailed detector models, demonstrated on single- and two-photon states.

## Contribution

We develop a measurement scheme that reconstructs phase-space distributions independently of detector specifics, generalizing traditional quasiprobability distributions.

## Key findings

- Successfully implemented with transition-edge sensors
- Revealed features of heralded photon states in phase space
- Certified nonclassicality with high statistical significance

## Abstract

The representation of quantum states via phase-space functions constitutes an intuitive technique to characterize light. However, the reconstruction of such distributions is challenging as it demands specific types of detectors and detailed models thereof to account for their particular properties and imperfections. To overcome these obstacles, we derive and implement a measurement scheme that enables a reconstruction of phase-space distributions for arbitrary states whose functionality does not depend on the knowledge of the detectors, thus defining the notion of detector-agnostic phase-space distributions. Our theory presents a generalization of well-known phase-space quasiprobability distributions, such as the Wigner function. We implement our measurement protocol, using state-of-the-art transition-edge sensors without performing a detector characterization. Based on our approach, we reveal the characteristic features of heralded single- and two-photon states in phase space and certify their nonclassicality with high statistical significance.