Regensburg 2010 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 59: Quantum Dots and Wires, Optical Properties V
HL 59.6: Vortrag
Donnerstag, 25. März 2010, 17:15–17:30, H14
Coherent manipulation of the exciton phase via the AC-Stark effect — •Simon Gordon1, Steffen Michaelis de Vasconcellos1, Max Bichler2, Torsten Meier1, and Artur Zrenner1 — 1CeOPP, Universität Paderborn, Paderborn, Germany — 2WSI, TU München, Garching, Germany
Excitons in InGaAs/GaAs quantum dots are an interesting implementation of qubits, especially concerning the interaction with photons. To achieve universal coherent control over a single qubit, a quantum phase gate is fundamental requirement. In our current contribution, we show that a quantum phase for an exciton qubit can be manipulated coherently by a non-resonant light field via the AC-Stark effect.
The effect of this non-resonant light field is investigated experimentally as well as theoretically by calculations based on the optical Bloch equations. In the experimental realization we used a Ramsey-like setup [1] to detect the phase shift and possible effects on the population of the qubit. Thereby, a first resonant laser pulse creates an coherent superposition of the exciton state and a second laser pulse after a fixed time delay probes the phase and population of the exciton qubit. During the delay time, the quantum phase is manipulated with either a non-resonant cw laser or a non-resonant ps laser pulse. We could demonstrate, that under selected conditions only the phase of the exciton qubit and not its population is influenced. The phase shift is thereby a function of the amplitude and the detuning of the non-resonant light field.
[1] Stufler et al. Phys. Rev. Lett. 96, 037402 (2006)