Professor Ian Walmsley CBE FRS FCGI

Abstract:

Alkali-filled hollow-core fibers are a promising medium for investigating light–matter interactions, especially at the single-photon level, due to the tight confinement of light and high optical depths achievable by light-induced atomic desorption (LIAD). However, until now these large optical depths could only be generated for seconds, at most once per day, severely limiting the practicality of the technology. Here we report the generation of the highest observed transient (>105 for up to a minute) and highest observed persistent (>2000 for hours) optical depths of alkali vapors in a light-guiding geometry to date, using a cesium-filled Kagomé-type hollow-core photonic crystal fiber (HC-PCF). Our results pave the way to light–matter interaction experiments in confined geometries requiring long operation times and large atomic number densities, such as generation of single-photon-level nonlinearities and development of single photon quantum memories.

Abstract:

We demonstrate storage of heralded single photons in a room-temperature quantum memory, a key step towards scalable quantum networks. We evaluate the photon statistics of the stored photons and discuss limitations from four-wave mixing noise.