Experimental quantum tomography of a homodyne detector

TL;DR

This paper presents a quantum tomography method to fully characterize homodyne detectors by expanding their operator measure in the quadrature basis, validated on nonclassical states, and used to estimate quantum efficiency.

Contribution

It introduces a novel tomographic technique for quantum-level characterization of homodyne detectors using coherent states and least squares reconstruction.

Findings

Successfully reconstructed the detector's operator measure.

Validated the method on nonclassical states.

Estimated the detector's quantum efficiency.

Abstract

We suggest and demonstrate a tomographic method to fully characterize homodyne detectors at the quantum level. The operator measure associated with the detector is expanded in the quadrature basis and probed with a set of coherent states. The coefficients of the expansion are retrieved using a least squares algorithm. We then validate the reconstructed operator measure on nonclassical states. Finally, we exploit results to estimate the overall quantum efficiency of the detector.