Atom-Resonant Heralded Single Photons by Interaction-Free Measurement

TL;DR

This paper reports the generation of rubidium-resonant heralded single photons with narrow bandwidth using a novel atom-based filter, demonstrating high atom-resonance and low multi-photon contamination for quantum memory applications.

Contribution

The authors introduce a new atom-based filter utilizing interaction-free measurement principles to produce narrowband, atom-resonant heralded single photons for quantum memories.

Findings

At least 94% of heralded photons are atom-resonant.

Achieved a $g_c^{(2)}(0)$ of 0.040, indicating low multi-photon probability.

Bandwidth narrowed to 7 MHz for compatibility with quantum memories.

Abstract

We demonstrate the generation of rubidium-resonant heralded single photons for quantum memories. Photon pairs are created by cavity-enhanced down-conversion and narrowed in bandwidth to 7 MHz with a novel atom-based filter operating by "interaction-free measurement" principles. At least 94% of the heralded photons are atom-resonant as demonstrated by a direct absorption measurement with rubidium vapor. A heralded auto-correlation measurement shows $g_c^{(2)}(0)=0.040 \pm 0.012$, i.e., suppression of multi-photon contributions by a factor of 25 relative to a coherent state. The generated heralded photons can readily be used in quantum memories and quantum networks.