Regensburg 2013 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 60: Focus Session: Coherent dynamics in semiconductor nanostructures and coupled devices

HL 60.5: Topical Talk

Wednesday, March 13, 2013, 17:15–17:45, H16

Coherent optical control of quantum dot spins and spin-photon entanglement — •Sven Höfling^{1, 2}, Kristiaan De Greve², Peter L. McMahon², David Press², Leo Yu², Jason S. Pelc², Chandra M. Natarajan², Na Young Kim², Thaddeus Ladd², Eisuke Abe², Sebastian Maier¹, Dirk Bisping¹, Christian Schneider¹, Martin Kamp¹, Robert H. Hadfield³, Alfred Forchel², M. M. Fejer¹, and Yoshihisa Yamamoto¹ — ¹Technische Physik, Universität Würzburg, Germany — ²Ginzton Laboratory, Stanford University, USA — ³Heriot-Watt University, Edinburgh, UK

Quantum computer and long-distance quantum communication technologies require robust qubits that can be coherently controlled, interfaced and entangled. Single III-V semiconductor quantum-dots in microcavities are ultra-bright emitters of indistinguishable single photons, and single electron and hole spins confined in them can serve as embedded quantum memories. In this contribution, coherent control experiments of single electron and hole qubits in a Voigt magnetic field will be summarized. By employing spin echo techniques we obtain coherence times of both qubit carrier types in the microsecond-range. Within this time scale about 10^5 complete single qubit rotations can be coherently performed with ultrafast optical pulses. Utilizing the $\Lambda$-type system of a single quantum-dot containing a single electron spin and ultrafast non-linear frequency conversion, quantum-dot spin-photon entanglement is demonstrated and presented.