Regensburg 2019 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 47: Quantum dots and wires: Optical properties II
HL 47.11: Vortrag
Freitag, 5. April 2019, 12:15–12:30, H34
Dephasing dynamics of optically active hole spin qubits in self-assembled quantum dots — •Friedrich Sbresny1, Tobias Simmet1, William Rauhaus1, Malte Kremser1, Fuxiang Li2, Nikolai Sinitsyn2, Kai Müller1, and Jonathan Finley1 — 1Walter Schottky Institut and Physik Department, Technische Universität München, 85748 Garching, Germany — 2Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico, 87545 USA
Single spins in self-assembled InGaAs quantum dots (QDs) are promising candidates for spin-photon interfaces with applications in quantum technologies. While an electron spin in a QD rapidly dephases within T2*=2ns [1], it was predicted that a single heavy hole spin would exhibit two orders of magnitude longer dephasing times. At zero magnetic field, through time-domain measurements of the net hole spin projection we find a hole spin dephasing time of 300ns. This largely reduced dephasing rate can be explained by the much weaker hyperfine contact interaction of a valence band hole with the nuclei. Measurements of T2* through time-resolved Ramsey interference show faster dephasing rates with increasing magnetic field. We attribute this to electronic noise, which broadens the distribution of Zeeman frequencies via the linear coupling of the hole g-tensor to the local electric field. Strategies to counteract this noise source as well as spin-echo measurements to obtain the single spin coherence time T2 are discussed [2].
[1] A. Bechtold et al., Nature Physics 11, 1005-1008 (2015)
[2] T. Simmet et al, in preparation