Phase-sensitive characterization of a quantum frequency converter by spectral interferometry

TL;DR

This paper presents a novel spectral interferometry technique for fully characterizing the phase and spectral transfer function of quantum frequency converters, demonstrated on a Bragg-scattering four-wave mixing device.

Contribution

The authors introduce a new phase-sensitive spectral characterization method for quantum frequency converters, enabling complete Green's function recovery.

Findings

Successfully recovered the complex spectral transfer function.

Identified active and passive regions within the frequency converter.

Validated the technique with experimental results.

Abstract

We introduce an experimental technique for complete phase-sensitive characterization of arbitrary unitary spectral-temporal transformations of optical modes. Our method recovers the complex spectral transfer function, or Green's function, of a frequency converter by analyzing spectral interference in the response to a tunable bichromatic probe. We perform a proof-of-concept experiment on a frequency conversion module based on Bragg-scattering four-wave mixing in photonic crystal fiber. Our results validate our technique by recovering useful information in the phase of the Green's function, revealing the relative positions of regions of active frequency conversion and passive dispersive propagation within the module. Our work introduces a new approach to characterizing the performance of a variety of active devices with diverse applications in emerging quantum technologies.