Complete Characterization of Quantum-Optical Processes

TL;DR

This paper introduces a highly accurate method for fully characterizing quantum optical processes by analyzing their effects on coherent states using homodyne tomography, demonstrated on a squeezed vacuum.

Contribution

It presents a novel protocol for complete quantum process characterization using classical light sources and homodyne tomography, enabling high-precision assessment of quantum devices.

Findings

Successfully characterized a quantum process affecting squeezed vacuum

Verified the protocol's accuracy through experimental evaluation

Achieved high-fidelity process reconstruction

Abstract

The technologies of quantum information and quantum control are rapidly improving, but full exploitation of their capabilities requires complete characterization and assessment of processes that occur within quantum devices. We present a method for characterizing, with arbitrarily high accuracy, any quantum optical process. Our protocol recovers complete knowledge of the process by studying, via homodyne tomography, its effect on a set of coherent states, i.e. classical fields produced by common laser sources. We demonstrate the capability of our protocol by evaluating and experimentally verifying the effect of a test process on squeezed vacuum.