High-efficiency single-photon source above the loss-tolerant threshold for efficient linear optical quantum computing

TL;DR

This paper presents a highly efficient, on-demand single-photon source that surpasses the loss threshold necessary for scalable linear optical quantum computing, demonstrating high purity, indistinguishability, and system efficiency.

Contribution

The authors develop a deterministic single-photon source using tailored laser pulses on a quantum dot coupled to a microcavity, achieving efficiency above the critical threshold for quantum computing.

Findings

Single-photon purity of 0.9795(6)

Photon indistinguishability of 0.9856(13)

System efficiency of 0.712(18)

Abstract

Photon loss is the biggest enemy for scalable photonic quantum information processing. This problem can be tackled by using quantum error correction, provided that the overall photon loss is below a threshold of 1/3. However, all reported on-demand and indistinguishable single-photon sources still fall short of this threshold. Here, by using tailor shaped laser pulse excitation on a high-quantum efficiency single quantum dot deterministically coupled to a tunable open microcavity, we demonstrate a high-performance source with a single-photon purity of 0.9795(6), photon indistinguishability of 0.9856(13), and an overall system efficiency of 0.712(18), simultaneously. This source for the first time reaches the efficiency threshold for scalable photonic quantum computing. With this source, we further demonstrate 1.89(14) dB intensity squeezing, and consecutive 40-photon events with 1.67 mHz count rate.