Dresden 2014 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 16: Electron spin qubits in semiconductor quantum dots (Focus session with TT)

HL 16.3: Vortrag

Montag, 31. März 2014, 15:45–16:00, POT 051

Reservoir-assisted coherent control of a quantum-dot spin — •Carsten H. H. Schulte1, Jack Hansom1, Claire Le Gall1, Clemens Matthiesen1, Jacob M. Taylor2,3, and Mete Atatüre11Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, United Kingdom — 2Joint Quantum Institute, University of Maryland, College Park, Maryland 20742, USA — 3National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA

The interaction of a quantum-dot electron spin with the nuclear spins of its environment has attracted a lot of attention recently [1]. In equilibrium, the stochastic polarisation of the unperturbed nuclear spin bath leads to a splitting of the electron spin states. Here, we show that this effective Zeeman splitting is smaller than the linewidth of the charged exciton transition. The transitions in the unperturbed regime represent dynamically evolving Λ-systems. Harnessing these level schemes with sub-linewidth spin splittings, we implement spin-bath enabled coherent population trapping in the absence of an external magnetic field. We verify the coherence of the created spin state by coherent dark- and bright-state basis rotation through phase control of the laser fields, yielding arbitrary spin state initialisation and spin rotation with only hyperfine-induced spin orientation. The shown sub-linewidth level splitting advantageously reduces the influence of Larmor precession in spin manipulation schemes and facilitates photonic cluster state generation by triggered photon emission [2].

[1] Urbaszek et al., Rev. Mod. Phys. 85, 79-133 (2013).

[2] Lindner et al., Phys. Rev. Lett. 103, 113602 (2009).

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