Nanophotonic quantum phase switch with a single atom.
By analogy to transistors in classical electronic circuits, quantum optical switches are important elements of quantum circuits and quantum networks. Operated at the fundamental limit where a single quantum of light or matter controls another field or material system, such a switch may enable applications such as long-distance quantum communication, distributed quantum information processing and metrology, and the exploration of novel quantum states of matter. Here, by strongly coupling a photon to a single atom trapped in the near field of a nanoscale photonic crystal cavity, we realize a system in which a single atom switches the phase of a photon and a single photon modifies the atom's phase. We experimentally demonstrate an atom-induced optical phase shift that is nonlinear at the two-photon level, a photon number router that separates individual photons and photon pairs into different output modes, and a single-photon switch in which a single 'gate' photon controls the propagation of a subsequent probe field. These techniques pave the way to integrated quantum nanophotonic networks involving multiple atomic nodes connected by guided light.
1] Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA [2] Department of Physics and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA [3].
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TG
Tiecke
1] Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA [2].
J D
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Thompson
1] Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA [2] Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
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de Leon
Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA.
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Liu
Department of Physics and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
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Vuletić
Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA.
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Lukin