High-purity single-photon generation based on cavity QED

TL;DR

This paper presents a cavity QED scheme employing a four-level atomic system to generate high-purity single photons with minimal re-excitation, enhancing quantum communication and computation capabilities.

Contribution

The proposed four-level system scheme significantly reduces re-excitation in single-photon generation, outperforming traditional three-level systems using current cavity-QED technology.

Findings

Re-excitation probability approaches zero with increased laser power.

High-purity single photons achievable without reducing generation probability.

Compatible with existing cavity-QED setups.

Abstract

We propose a scheme for generating a high-purity single photon on the basis of cavity quantum electrodynamics (QED). This scheme employs a four-level system including two excited states, two ground states, and two driving lasers; this structure allows the suppression of the re-excitation process due to the atomic decay, which is known to significantly degrade the single-photon purity in state-of-the-art photon sources using a three-level system. Our analysis shows that the re-excitation probability arbitrarily approaches zero without sacrificing the photon generation probability when increasing the power of the driving laser between the excited states. This advantage is achievable by using current cavity-QED technologies. Our scheme can contribute to developing distributed quantum computation or quantum communication with high accuracy.