Serial-parallel conversion for single photons with heralding signals

TL;DR

This paper introduces a heralded serial-parallel conversion method for single photons that significantly improves efficiency over traditional unheralded approaches, with experimental validation demonstrating near-perfect conversion when losses are minimized.

Contribution

The paper presents a novel heralded serial-parallel conversion technique for single photons, achieving higher efficiency than unheralded methods and providing experimental proof of concept.

Findings

Conversion efficiency of 0.533 achieved, surpassing 0.5 for unheralded photons.

Efficiency can be increased to 0.996 after correcting for losses.

Experimental demonstration with two photons confirms theoretical predictions.

Abstract

We present serial-parallel conversion for a heralded single photon source (heralded SPS). We theoretically show that with the heralding signal, the serial-parallel converter can route a stream of n photons to n different spatial modes more efficiently than is the case without using a heralding signal. We also experimentally demonstrate serial-parallel conversion for two photons generated from a heralded SPS. We achieve a conversion efficiency of 0.533 \pm 0.003, which exceeds the maximum achievable efficiency of 0.5 for serial-parallel conversion using unheralded photons, and is double the efficiency (0.25) for that using beamsplitters. When the losses in the optical converter are corrected for, the efficiency of the current setup can be increased up to 0.996 \pm 0.006.