Berlin 2018 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 32: Quantum dots and wires: Optical properties II
HL 32.6: Vortrag
Mittwoch, 14. März 2018, 16:30–16:45, A 151
Coherence of a dynamically decoupled quantum-dot hole spin — •Lukas Huthmacher, Robert Stockill, Claire Le Gall, and Mete Atatüre — Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge, CB3 0HE, UK
Single spins in self-assembled InGaAs quantum dots are promising candidates for the implementation of distributed quantum information processing. For the electron the strong hyperfine coupling to the surrounding nuclei dephases the spin states in a few ns, hindering the quality of the spin-photon interface. In contrast, a hole spin is expected to couple less to the nuclear spin bath, providing a promising alternative. While it has been shown that holes can offer a longer dephasing time, T2* [1], future progress hinges on what coherence times can be achieved through decoupling.
In this work, we establish the regimes that allow for a highly coherent hole spin in this system. We observe a pick-up and decay with external magnetic field for both the inhomogeneous dephasing time, T2*, as well as the coherence time, T2. We show that the decoherence of the hole is still dictated by the hyperfine coupling to the nuclear spin environment for fields up to a few Tesla, whereas electrical noise dominates at higher fields. We implement dynamic decoupling in the latter regime to actively protect the hole spin, allowing us to achieve T2 = 4.4 µs, the longest for any spin in this system. Finally, we independently determine the local electrical environment which quantitatively supports the improvement of coherence we achieve with dynamic decoupling.
[1] D. Brunner et al. Nature 456, 218 (2008)