Generation of single photons with highly tunable wave shape from a cold atomic quantum memory

TL;DR

This paper presents a highly tunable single photon source using a cold atomic ensemble, capable of producing photons with customizable wave shapes and durations, suitable for advanced quantum information applications.

Contribution

The work demonstrates precise control over photon wave shapes and durations from a cold atomic quantum memory, including ultra-long and complex waveforms, advancing quantum light source technology.

Findings

Photon wave shape can be precisely controlled by the read pulse shape.

Generated photons have durations up to 10 microseconds with high efficiency.

Photons exhibit non-classical antibunching and are in a pure quantum state.

Abstract

We report on a single photon source with highly tunable photon shape based on a cold ensemble of Rubidium atoms. We follow the DLCZ scheme to implement an emissive quantum memory, which can be operated as a photon pair source with controllable delay. We find that the temporal wave shape of the emitted read photon can be precisely controlled by changing the shape of the driving read pulse. We generate photons with temporal durations varying over three orders of magnitude up to 10 {\mu}s without a significant change of the read-out efficiency. We prove the non-classicality of the emitted photons by measuring their antibunching, showing near single photon behavior at low excitation probabilities. We also show that the photons are emitted in a pure state by measuring unconditional autocorrelation functions. Finally, to demonstrate the usability of the source for realistic applications, we create ultra-long single photons with a rising exponential or doubly peaked wave shape which are important for several quantum information tasks.