Atomic Physics Seminars

Wednesday, April 29, 2009
3:30 PM
Physics Building, Room 204
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"Producing Photon-Pairs using non-linear optical waveguides"

Alexander Ling , NIST
[Host: Olivier Pfister]
Correlated photon-pairs are a useful resource in obtaining heralded single photons or for the generation of entangled pairs of qubits. The workhorse method of generating photon-pairs has been Spontaneous Parametric Down-Conversion inside bulk nonlinear optical crystals. However, the emission profile of such photon-pairs is always multi-mode, and the overall coupling efficiency into single-mode optical fibers is poor. In order to enhance the coupling efficiency, it is desirable to produce photon-pairs inside engineered waveguide structures that have a higher degree of overlap with single-mode fibers. In this talk, I will present some of our recent work in generating and characterizing photon-pairs using two types of waveguides: a) a waveguide formed from periodically-poled KTP, and b) a photonic-crystal fiber (PCF). With the waveguide source, we have demonstrated photon-pair production via two different SPDC phase-matching methods (Type-0 and Type-II) from a single waveguide, and at the same temperature. I will also present the measured coincidence spectrum for the two phase-matching methods and discuss the differences between them. The PCF source generates photon-pair via Four-Wave Mixing, and is a more mature source compared to the PPKTP waveguide. We have been able to demonstrate the generation of photon-pairs that are indistinguishable, as well as polarization-entangled. In this talk I will describe our recent innovations to improve the coupling efficiency and stability of this source.

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