Mapping coherence in measurement via full quantum tomography of a hybrid optical detector

TL;DR

This paper demonstrates full quantum detector tomography of a hybrid optical detector, revealing its wave and particle sensitivities, and introduces new theoretical tools for large-scale quantum measurement characterization.

Contribution

It presents the first full quantum tomography of a hybrid optical detector, enabling detailed analysis of its coherence and tunability, with the largest parametrization to date.

Findings

Revealed the role of coherence in quantum measurements

Demonstrated tunability of hybrid quantum-optical detectors

Developed novel theoretical tools for large-scale quantum tomography

Abstract

Quantum states and measurements exhibit wave-like --- continuous, or particle-like --- discrete, character. Hybrid discrete-continuous photonic systems are key to investigating fundamental quantum phenomena, generating superpositions of macroscopic states, and form essential resources for quantum-enhanced applications, e.g. entanglement distillation and quantum computation, as well as highly efficient optical telecommunications. Realizing the full potential of these hybrid systems requires quantum-optical measurements sensitive to complementary observables such as field quadrature amplitude and photon number. However, a thorough understanding of the practical performance of an optical detector interpolating between these two regions is absent. Here, we report the implementation of full quantum detector tomography, enabling the characterization of the simultaneous wave and photon-number sensitivities of quantum-optical detectors. This yields the largest parametrization to-date in quantum tomography experiments, requiring the development of novel theoretical tools. Our results reveal the role of coherence in quantum measurements and demonstrate the tunability of hybrid quantum-optical detectors.