Integrated photonic sensing

TLDR

Loss and fabrication imperfections limit precision in photonic quantum technologies, particularly affecting Holland‑Burnett state‑based measurements. The authors aim to build a modular integrated photonics platform for quantum sensing that employs loss‑tolerant Holland‑Burnett states and heralded single‑photon sources. They use spontaneous four‑wave mixing in birefringent fiber to generate pure heralded photons, optimize these sources, implement programmable circuits with ratiometric beam‑splitter characterization, and provide a framework for state tomography with lossy detectors.

Abstract

Loss is a critical roadblock to achieving photonic quantum-enhanced technologies. We explore a modular platform for implementing integrated photonics experiments and consider the effects of loss at different stages of these experiments, including state preparation, manipulation and measurement. We frame our discussion mainly in the context of quantum sensing and focus particularly on the use of loss-tolerant Holland-Burnett states for optical phase estimation. In particular, we discuss spontaneous four-wave mixing in standard birefringent fibre as a source of pure, heralded single photons and present methods of optimising such sources. We also outline a route to programmable circuits which allow the control of photonic interactions even in the presence of fabrication imperfections and describe a ratiometric characterisation method for beam splitters which allows the characterisation of complex circuits without the need for full process tomography. Finally, we present a framework for performing state tomography on heralded states using lossy measurement devices. This is motivated by a calculation of the effects of fabrication imperfections on precision measurement using Holland-Burnett states.