Berlin 2005 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

HL: Halbleiterphysik

HL 36: Quantenpunkte und -dr
ähte: Optische Eigenschaften III

HL 36.1: Vortrag

Montag, 7. März 2005, 10:00–10:15, TU P164

Optically Programmable Electron Spin Memory Using InGaAs Quantum Dots — •Dominik Heiss, Miro Kroutvar, Yann Ducommun, Max Bichler, Dieter Schuh, Gerhard Abstreiter, and Jonathan J Finley — Walter Schottky Institut, TU Muenchen, Am Coulombwall 3, 85748 Garching, Germany

The spin of a single electron localized in a quantum dot (QD) in static magnetic fields provides a natural two level system that has been proposed to be suitable as a quantum bit [1].

We present a spin memory device which enables the preparation, storage and readout of electron spins. This device is based on charging of a sub-ensemble of a single layer of InGaAs self-assembled QDs with resonant optical excitation. These charges can be stored over microsecond timescales without any loss or interdot redistribution processes [2]. Using circular polarized excitation we are able to define the spin orientation of the stored electrons. This device allows us to investigate the temporal dynamics of localized spins in magnetic fields by varying the storage time. Our results reveal very long spin lifetimes T1, with a lower limit of  20ms at 4T and 1K. Analyzing the magnetic field dependence we identified the dominant spin-flip mechanism to be spin-orbit mixing of the Zeeman levels mediated by one-phonon scattering at low temperatures and high magnetic fields [3]. [1] Loss, DiVicenzo, Phys. Rev. A 57 (1998) [2] Kroutvar et al., Appl. Phys. Lett. 83 (2003) [3] Kroutvar et al., Nature 432 (2004)