Towards single-photon switching via two-photon absorption in Rb vapour

Davis, Will

Kyle W. Martin, Gretchen R. Phelps, N. Lemke +3 more

Tabijah Wasawo, Carlo Page, Alex O. C. Davis +2 more

Strong nonlinearities mediated by atomic vapours have the potential to achieve optically controlled switching at room temperature, opening the way to scalable quantum computing. A strong candidate for engineering such interactions is the combination of optical waveguides and cavities with warm alkali vapours. Here we report the implementation of a doubly resonant cavity that translates Kerr nonlinearity induced by an optical control field into a switch for a signal field. We investigate losses and consider optimised designs. We discuss this model in the context of building practical switching devices with applications to logic gate operations at room temperature.

A. Quattropani, B. Girlanda

Georgia Booton, Cameron McGarry, Tabijah Wasawo +4 more

The ability to dynamically route and manage optical signals at high speeds with low-loss is a substantial challenge in quantum optics. Existing optical switches, such as electro-optic phase modulators either achieve high-speed or low insertion losses, but rarely both. However, optically-controlled phase modulation in atomic vapour promises a pathway for efficient, high-bandwidth switching [1]. These characteristics are critical for single photon multiplexing in quantum technologies, implementing loop memory schemes and addressing scalability challenges in photonic quantum computation [2]. We present a cavity based system that can deliver high-speed all-optical switching of a signal field with minimal loss by accessing the strong two photon absorption in warm rubidium vapour via a counter-propagating control field.

Vivek Venkataraman, Kasturi Saha, Pablo Londero +1 more

We show 20% all-optical modulation with less than 2 nW total power via non-degenerate two-photon absorption in Rb vapor confined to a photonic bandgap fiber. This corresponds to about 15 photons of switching energy.