Heralding efficiency and correlated-mode coupling of near-IR fiber coupled photon pairs

TL;DR

This paper presents a comprehensive experimental study of heralding efficiency and correlated-mode coupling in near-IR fiber-coupled photon pairs, achieving record-high efficiency and confirming theoretical models.

Contribution

It introduces a reconfigurable optical setup and demonstrates the highest correlated-mode coupling efficiency to date, advancing the understanding of photon pair generation and coupling in quantum optics.

Findings

Achieved a correlated-mode coupling efficiency of 97%

Confirmed the agreement between experimental data and theoretical models

Demonstrated high heralding efficiency in fiber-coupled photon pairs

Abstract

We report on a systematic experimental study of heralding efficiency and generation rate of telecom-band infrared photon pairs generated by spontaneous parametric down-conversion and coupled to single mode optical fibers. We define the correlated-mode coupling efficiency--an inherent source efficiency--and explain its relation to heralding efficiency. For our experiment, we developed a reconfigurable computer controlled pump-beam and collection-mode optical apparatus which we used to measure the generation rate and correlated-mode coupling efficiency. The use of low-noise, high-efficiency superconducting nanowire single-photon detectors in this setup allowed us to explore focus configurations with low overall photon flux. The measured data agree well with theory and we demonstrated a correlated-mode coupling efficiency of $97 \pm 2\%$, which is the highest efficiency yet achieved for this type of system. These results confirm theoretical treatments and demonstrate that very high overall heralding efficiencies can, in principle, be achieved in quantum optical systems. It is expected that these results and techniques will be widely incorporated into future systems that require, or benefit from, a high heralding efficiency.