Reception in Hbar at 3:30 pm
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 [1,2], 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, and can be harnessed to perform a variety of photon-atom and photon-photon gates .
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). Our realisation relies on a nanofiber-coupled microsphere resonator coupled to single Rb atoms. 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, achieving non-classical fidelities (0.73-0.79) in both directions at ~70% efficiency. The gate takes less than 50 ns, orders of magnitude faster than previously demonstrated protocols. Requiring no control fields and applicable to any waveguide-coupled material Lambda system, this scheme provides a versatile building block for scalable quantum networks and distributed quantum computation.
 Science 345, 903 (2014)
 Nature Photonics 10, 19 (2016)
 Phys. Rev. A. 82, 10301 (2010)
 Phys. Rev. A. 95, 0333814 (2017)