Extraction of a single photon from an optical pulse

TL;DR

This paper presents a deterministic method for extracting a single photon from an optical pulse using single-photon Raman interaction, improving success probability over probabilistic methods and enabling new quantum communication applications.

Contribution

The authors demonstrate a novel deterministic photon extraction scheme utilizing SPRINT with a single atom, surpassing probabilistic approaches in efficiency.

Findings

Extraction probability limited mainly by linear loss

Probabilities close to unity are feasible with current technology

Method enables photon reuse for quantum protocols

Abstract

Removing a single photon from a pulse is one of the most elementary operations that can be performed on light, having both fundamental significance and practical applications in quantum communication and computation. So far, photon subtraction, in which the removed photon is detected and therefore irreversibly lost, has been implemented in a probabilistic manner with inherently low success rates using low-reflectivity beam splitters. Here we demonstrate a scheme for the deterministic extraction of a single photon from an incoming pulse. The removed photon is diverted to a different mode, enabling its use for other purposes, such as a photon number-splitting attack on quantum key distribution protocols. Our implementation makes use of single-photon Raman interaction (SPRINT) with a single atom near a nanofibre-coupled microresonator. The single-photon extraction probability in our current realization is limited mostly by linear loss, yet probabilities close to unity should be attainable with realistic experimental parameters.