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HL: Fachverband Halbleiterphysik
HL 38: Quantum light sources based on solid state systems: Status and visions I (Focus session with TT)
HL 38.1: Topical Talk
Dienstag, 1. April 2014, 09:30–10:00, POT 251
Nonclassical light from semiconductor quantum dots — •Gregor Weihs1,2, Tobias Huber1, Harishankar Jayakumar1, Thomas Kauten1, and Ana Predojević1 — 1Institut für Experimentalphysik, Universität Innsbruck, Technikerstr. 25, 6020 Innsbruck, Austria — 2Institute for Quantum Computing, University of Waterloo, 200 University Ave W, Waterloo, ON N2L 3G1, Canada
For fundamental tests of quantum physics as well as for quantum communications non-classical states of light are an important tool. In our research we focus on developing semiconductor-based and integrated sources of single photons and entangled photon pairs.
In this talk we will present our work on single InAs/GaAs quantum dots. For the highest degree of quantum control we use resonant two-photon excitation to deterministically trigger a biexciton-exciton cascade. We block the pump light from the detectors by using side excitation through the waveguide mode of a planar microcavity. We demonstrate Rabi oscillations, Ramsey interference and all-optical coherent control of the quantum dot resulting in single and paired photons with a high degree of indistinguishability [1]. Using novel quantum optical assessment tools we are then able to show the non-classical and non-Gaussian characteristics of the emitted photons.
This indistinguishability eventually results in time-bin entangled photon pairs through the biexciton-exciton cascade. Time-bin entanglement is a useful variant for long distance communication because it is robust against decoherence in optical fibers. Two successive coherent pulses excite the dot ei-ther in the early or in the late pulse. The emitted photons pass imbalanced interferometers for analy-sis in the energy basis. Through quantum state tomography we are able to demonstrate significant entanglement of the emitted pairs.
This work was supported by the ERC and CIFAR.
[1]H. Jayakumar, A. Predojevic, T. Huber, T. Kauten, G. S. Solomon & G. Weihs, Deterministic Photon Pairs and Coherent Optical Control of a Single Quantum Dot, Phys. Rev. Lett. 110, 135505 (2013).