Cascading Quantum Light-Matter Interfaces

TL;DR

This paper demonstrates the cascading of quantum light-matter interfaces using warm vapor, enabling sequential storage of light pulses with maintained signal quality, a key step towards scalable quantum networks.

Contribution

It introduces a method for cascading quantum light-matter interfaces with warm vapor, showing sequential storage of weak light pulses while preserving signal integrity.

Findings

Signal-to-background ratio remains >1 after cascading

Effective storage of pulses with 8 photons on average

Demonstrates feasibility for quantum network nodes

Abstract

The ability to interface multiple optical quantum devices is a key milestone towards the development of future quantum networks that are capable of sharing and processing quantum information encoded in light. One of the requirements for any node of these quantum networks will be cascadability, i.e. the ability to drive the input of a node using the output of another node. Here, we report the cascading of quantum light-matter interfaces by storing few-photon level pulses of light in warm vapor followed by the subsequent storage of the retrieved field onto a second ensemble. We demonstrate that even after the sequential storage, the final signal-to-background ratio can remain greater than 1 for weak pulses containing 8 input photons on average.