Regensburg 2013 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 91: Poster Session: Quantum dots and wires: preparation & characterization & optical properties & transport properties

HL 91.12: Poster

Donnerstag, 14. März 2013, 16:00–20:00, Poster A

Temperature dependence of hole spin coherence measured by spin echo andspin mode locking in an ensemble of (In,Ga)As quantum dots — •Steffen Varwig¹, Alexandre René¹, Alex Greilich¹, Dmitri R. Yakovlev¹, Dirk Reuter², Andreas D. Wieck², and Manfred Bayer¹ — ¹Experimentelle Physik II, TU Dortmund, D-44221 Dortmund, Germany — ²Angewandte Festkörperphysik, Ruhr- Universität Bochum, D-44780 Bochum, Germany

Electron and hole spins confined in quantum dots (QDs) are promising candidates for implementing qubits in semiconductors. One of the spin’s most important properties for quantum information processing is its coherence time T₂. For electrons in (In,Ga)As QDs, T₂ is determined to be around 3 µs [1]; for holes it is in the order of 1 µs [2]. Although for electron spins the coherence time is mainly limited by hyperfine interactions with the QD’s nuclei, for hole spins it is known that the coupling constant is about ten times weaker [3].

To study the hole spin coherence in QDs we performed optical time-resolved pump-probe ellipticity measurements on the hole spin polarization in (In,Ga)As QDs. In particular we investigated the temperature dependence of the coherence time T₂, making use of the spin mode-locking effect, demonstrated in reference [2], and spin echo techniques similar to those in reference [4].

[1] A. Greilich et al., Science 313, 341 (2006)

[2] S. Varwig et al., Phys. Rev. B 86, 075321 (2012)

[3] E. A. Chekhovich et al., Phys. Rev. Letters 106, 027402 (2011)

[4] A. Greilich et al., Nat. Phys. 5, 262-266 (2009)