Multiplexed single-photon state preparation using a fibre-loop architecture

TL;DR

This paper presents a practical multiplexing scheme using a fibre-loop architecture to enhance heralded single-photon generation efficiency from a single SPDC source, considering real-world experimental constraints.

Contribution

It introduces a time-bin encoding multiplexing method that improves heralding efficiency with simpler, more feasible technology compared to large SPDC source arrays.

Findings

The scheme increases heralding efficiency significantly.

It remains effective under realistic losses and detector inefficiencies.

The approach is compatible with current photonics technology.

Abstract

Heralded spontaneous parametric down-conversion (SPDC) has become the mainstay for single-photon state preparation in present-day photonics experiments. Because they are heralded, in principle one knows when a single photon has been prepared. However, the heralding efficiencies in experimentally realistic SPDC sources are typically very low. To overcome this, multiplexing techniques have been proposed which employ a bank of SPDC sources in parallel, and route successfully heralded photons to the output, thereby effectively boosting the heralding efficiency. However, running a large bank of independent SPDC sources is costly and requires complex switching. We analyse a multiplexing technique based on time-bin encoding that allows the heralding efficiency of just a single SPDC source to be increased. The scheme is simple and experimentally viable using present-day technology. We analyse the operation of the scheme in terms of experimentally realistic considerations, such as losses, detector inefficiency, and pump-power.