Dresden 2011 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 59: SKM Symposium: Semiconductor Nanophotonics - Quantum Optics and Devices (SYNP)

HL 59.2: Invited Talk

Wednesday, March 16, 2011, 15:00–15:30, TRE Ma

Two-photon Interference from Separate Quantum Dots — Edward Flagg, Andreas Muller, Sergey Polyakov, Alexander Ling, Alan Migdall, and •Glenn S. Solomon — Joint Quantum Institute, NIST & University of Maryland, Gaithersburg, MD USA

Semiconductor quantum dots (QDs) are attractive sources of single photons. When single photons emitted by two separate QDs are indistinguishable they will interfere when brought together at a beam splitter in a Hong-Ou-Mandel (HOM)-type experiment. This two-photon interference is needed in many proposed schemes for quantum computation and quantum networking involving quantum repeaters. However, while photons emitted by a single QD in a microcavity have been shown to be highly indistinguishable, mutually indistinguishable photons from separate QDs have only recently been produced [1].

Here we discuss results from an HOM experiment in which interference of photons from two QDs located in different samples is observed and is below the classical limit. We use strain-induced InAs QDs excited by a common pulsed laser. One QD is embedded in a planar optical microcavity of fixed resonant frequency, the other QD resides in a fiber-semiconductor tunable cavity. Despite having non-identical emission properties, the photons emitted from the QDs interfere in the HOM experiment. We obtain a probability of coalescence of the two photons of 18 %, which is increased to 47 % when post-selection within a small detection time window is applied. Dephasing processes limiting the coalescence, and extension to other quantum interfaces will be discussed. [1] E. B. Flagg, et al., Phys. Rev. Lett. 104, 137401 (2010).