Photon Sorting with a Quantum Emitter

TL;DR

This paper demonstrates a solid-state quantum emitter-based photon-sorting circuit that surpasses linear-optical Bell state measurement success limits, advancing scalable quantum communication and computing.

Contribution

It introduces a passive, on-chip photon-sorting device utilizing photon scattering in a quantum emitter, achieving higher success probabilities than linear optics.

Findings

Success probability of 62% for photon sorting.

BSMs with 57% success probability without ancillas.

Potential to improve success rate to over 65%.

Abstract

High-quality photonic Bell state measurements (BSMs) enable scalable universal quantum computing and long distance quantum communication. However, when implemented with linear optics, BSMs are fundamentally probabilistic, introducing substantial hardware overheads and limiting noise tolerance in photonic quantum computing architectures. Nonlinear interactions at the single-photon level can overcome these limitations by enabling near-deterministic photon-photon gates. Here, we demonstrate a passive photon-sorting circuit based on the induced nonlinearity arising from photon scattering in a solid-state quantum emitter. The scattering is implemented in a directional waveguide-emitter coupling interface and embedded on-chip into a linear optical circuit, through which we demonstrate sorting of one- and two-photon components with a success probability of 62%. We find that the current system can enable BSMs with a 57% post-selected success probability without ancillary photons, exceeding the linear-optical limit of 50%, and can be readily improved to >65% with design optimisations.