Dual-path state reconstruction scheme for propagating quantum microwaves and detector noise tomography

TL;DR

This paper presents a dual-path measurement scheme enabling quantum state reconstruction of propagating microwaves despite detector noise, using cross-correlations to determine quadrature moments and noise properties for tomography.

Contribution

It introduces a novel dual-path approach for quantum microwave state tomography that accounts for detector noise and allows complete quadrature measurement.

Findings

Successful proof-of-principle experiments with classical microwave mixtures

Effective noise characterization through the dual-path scheme

Feasibility of quantum microwave tomography demonstrated

Abstract

Quantum state reconstruction involves measurement devices that are usually described by idealized models, but not known in full detail in experiments. For weak propagating microwaves, the detection process requires linear amplifiers which obscure the signal with random noise. Here, we introduce a theory which nevertheless allows one to use these devices for measuring all quadrature moments of propagating quantum microwaves based on cross-correlations from a dual-path amplification setup. Simultaneously, the detector noise properties are determined, allowing for tomography. We demonstrate the feasibility of our novel concept by proof-of-principle experiments with classical mixtures of weak coherent microwaves.