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Passive and deterministic photon-atom gates

Event Details

Event Dates: 

Thursday, September 14, 2017 - 4:00pm

Seminar Location: 

  • JILA X317

Speaker Name(s): 

Barak Dayan

Speaker Affiliation(s): 

Weizmann Institute of Science
Seminar Type/Subject

Scientific Seminar Type: 

  • JILA Public Seminar

Event Details & Abstract: 

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 [3].

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.

 

Refs:

[1] Science 345, 903 (2014)

[2] Nature Photonics 10, 19 (2016)

[3] Phys. Rev. A. 82, 10301 (2010)

[4] Phys. Rev. A. 95, 0333814 (2017)