Prof. Dr. Barak Dayan

Weizmann Institute of Science, Israel

Single-photon Raman interaction (SPRINT) is a passive, interference-based effect that creates a deterministic coupling between single photons and a 3-level quantum emitter such as a single atom. As recently demonstrated in our lab, SPRINT enables controlling the state of a single atom solely by a single photon. Requiring no control-fields, SPRINT happens 'automatically' at the timescale of the cavity-enhanced spontaneous emission (a few ns).

I will describe our recent demonstration of a SPRINT-based quantum SWAP gate between a flying photonic qubit (encoded in the two possible input modes) and a stationary atomic qubit (encoded in the two atomic ground states). We apply the SWAP gate twice to demonstrate a passive quantum memory, i.e. to map the state of a photon onto the atom and then back onto a readout photon. Each swapping process is performed with an average fidelity that significantly exceeds the classical threshold. Our realisation relies on single 87Rb atoms coupled to fibre-coupled high-Q microsphere resonators, and the SWAP gates is performed in less than 50ns.

Host: Prof. Calarco, Tel. 22832, off.: 22830