Hannover 2016 – scientific programme

Parts | Days | Selection | Search | Updates | Downloads | Help

Q: Fachverband Quantenoptik und Photonik

Q 41: Quantum Effects: Entanglement and Decoherence II

Q 41.7: Talk

Wednesday, March 2, 2016, 16:15–16:30, f442

Intrinsic limit to electron spin coherence in InGaAs quantum dots — Robert Stockill, Claire Le Gall, Clemens Matthiesen, •Lukas Huthmacher, and Mete Atatüre — Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, UK

Single electron spins in self-assembled InGaAs quantum dots show outstanding photonic properties, allowing for ultrafast all-optical control [1] and therefore are a promising candidate for spin qubits. However, the fluctuations of the nuclear spin bath in the surrounding semiconductor limit the electron-spin dephasing to a few nanoseconds [2]. The exact mechanism leading to this limitation is masked by the measurement-induced dynamic polarisation of the nuclear bath, often revealed in the dragging of resonance frequencies, and hence remains unclear [3]. Here, we introduce an all-optical method allowing us to access the electron-spin without influencing the nuclear bath. By combining this method with a spin-echo decoupling scheme we are able to reach the intrinsic limit to electron-spin coherence, which, for our samples, amounts to a few microseconds, depending on the external magnetic fields. Taking into account the quadrupolar and Zeeman Hamiltonians we show that this bound is set by the quadrupolar interaction of the nuclear bath with inhomogeneous electric field gradients; a result of the naturally occurring strain in these systems. [1] Press, D. et al., Nature 456, 218-221 (2008) [2] Greilich, A. et al., Science 313, 341-345 (2006) [3] Latta, C. et al., Nature Phys. 5, 758-763 (2009)