Berlin 2014 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 59: Quantum information: Quantum computers and communication I
Q 59.5: Vortrag
Freitag, 21. März 2014, 11:30–11:45, DO26 207
Reservoir-assisted coherent control of a quantum dot spin qubit — •Jack Hansom1, Carsten H. H. Schulte1, Claire Le Gall1, Clemens Matthiesen1, Jacob M. Taylor2,3, and Mete Atature1 — 1Cavendish 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
In semiconductor quantum dots, the confined electron wavefunction is spread over O(105) lattice sites, and statistical fluctuations in the nuclear spin bath lead to a finite effective B-field: the Overhauser (OH) field [1]. By measuring the electron spin dynamics in the absence of an external B-field, we show that the fluctuating OH field leads to a sub-linewidth effective Zeeman splitting of the electron spin states, as well as the presence of spin-flip Raman transitions. We harness this hyperfine-generated Λ-system by performing two-laser coherent population trapping experiments, thus allowing for sub-linewidth creation of spin superpositions. Through phase control of one of the excitation lasers, we furthermore demonstrate coherent manipulation of the CPT basis. The demonstrated sub-linewidth coherent control lends itself to quantum information protocols requiring slow Larmor precession, such as photonic cluster state generation [2].
[1] Urbaszek et al., Rev. Mod. Phys. 85, 79-133 (2013).
[2] Lindner et al., Phys. Rev. Lett. 103, 113602 (2009).