Single-photon device requirements for operating linear optics quantum computing outside the post-selection basis

TL;DR

This paper provides detailed numerical simulations to establish realistic performance benchmarks for single-photon sources and detectors essential for advancing linear optics quantum computing beyond post-selected methods.

Contribution

It offers comprehensive simulation-based performance bounds for photonic devices and evaluates a single-photon source based on switched parametric down-conversion.

Findings

Performance bounds for realistic single-photon sources and detectors

Analysis of three switching approaches for photon hierarchy

Guidelines for optical device requirements in linear-optics quantum computing

Abstract

Photonics is a promising architecture for the realisation of quantum information processing, since the two-photon interaction, or non-linearity, necessary to build logical gates can efficiently be realised by the use of interference with ancillary photons and detection. Although single-photon sources and detectors are pivotal in realisations of such systems, clear guidelines for the required performance of realistic systems are yet to be defined. We present our detailed numerical simulation of several quantum optics circuits including sources and detectors all represented in multi-dimensional Fockspaces, which allows to obtain experimentally realistic performance bounds for for these devices. In addition, the single-photon source based on switched parametric down-conversion is studied, which in principle could reach the required performance. Three approaches for implementing the switching hierarchy of the photons are simulated, and their anticipated performance is obtained. Our results define the bar for the optical devices needed to achieve the first level of linear-optics quantum computing outside the coincidence basis.