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Q: Fachverband Quantenoptik und Photonik

Q 68: Quantum information: Photons and nonclassical light II

Q 68.4: Vortrag

Freitag, 22. März 2013, 14:45–15:00, F 142

Phase-locked indistinguishable flying qubits from a quantum dot — •Carsten H. H. Schulte, Clemens Matthiesen, Martin Geller, Claire Le Gall, Jack Hansom, Zhengyong Li, and Mete Atatüre — Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, United Kingdom

Optically active spins in self-assembled InAs quantum dots (QDs) represent one of many promising qubit candidates for quantum information processing. The entanglement of individual spins constitutes the smallest unit of a distributed quantum network and can be realised through quantum interference of flying qubits, i.e. photons emitted by the QD. For this, ideally indistinguishable photons from separate QDs are needed, the generation of which has proved challenging due to dephasing of the used optical QD transitions. Resonance fluorescence in the Heitler regime circumvents environment-induced dephasing and delivers single photons with a coherence well above the Fourier transform limit of the QD transition, the spectral shape of the photons being solely tailored by the excitation laser [1]. Using optical heterodyning, we demonstrate that QD photons and exciting laser field are phase-locked on a timescale exceeding 3 seconds. Exploiting this degree of mutual coherence we spectrally shape the emitted photons by modulating the excitation laser. Finally, successively emitted photons generated phase-locked to the excitation laser are proven to be fundamentally indistinguishable in Hong-Ou-Mandel interferometry [2].
[1] Matthiesen et al., Phys. Rev. Lett. 108, 093602 (2012).
[2] Matthiesen et al., arXiv:1208.1689 [quant-ph] (2012).