A. Greilich

Nuclei-Induced Frequency Focusing of Electron Spin Coherence

The hyperfine interaction of an electron with the nuclei is considered as the primary obstacle to coherent control of the electron spin in semiconductor quantum dots. We show, however, that the nuclei in singly charged quantum dots act constructively by focusing the electron spin precession about a magnetic field into well-defined modes synchronized with a laser pulse protocol. In a dot with a synchronized electron, the light-stimulated fluctuations of the hyperfine nuclear field acting on the electron are suppressed. The information about electron spin precession is imprinted in the nuclei and thereby can be stored for tens of minutes in darkness. The frequency focusing drives an electron spin ensemble into dephasing-free subspaces with the potential to realize single frequency precession of the entire ensemble.

Optical control of spin coherence in singly charged (In,Ga)As/GaAs quantum dots

Electron spin coherence has been generated optically in n-type modulation doped (In,Ga)As/GaAs quantum dots (QDs) which contain on average a single electron per dot. The coherence arises from resonant excitation of the QDs by circularly polarized laser pulses, creating a coherent superposition of an electron and a trion. Time dependent Faraday rotation is used to probe the spin precession of the optically oriented electrons about a transverse magnetic field. The coherence generation can be controlled by pulse intensity, being most efficient for (2n+1)pi pulses.

Optical control of one and two hole spins in interacting quantum dots

Researchers demonstrate fast, single-qubit gates using a sequence of 13 ps pulses. Two vertically stacked InAs/GaAs quantum dots were coupled through coherent tunnelling and charged with controlled numbers of holes. The interaction between hole spins was investigated by Ramsey fringe experiments, showing a tunable interaction range of tens of gigahertz.

Universal behavior of the electron g factor in Ga As ∕ Al x Ga 1 − x As quantum wells

The Zeeman splitting and the underlying

Optical spectroscopy of spin noise.

g

Effect of thermal annealing on the hyperfine interaction in InAs/GaAs quantum dots

factor for conduction-band electrons in

Spin Coherence of Holes inGaAs/(Al,Ga)AsQuantum Wells

\mathrm{Ga}\mathrm{As}∕{\mathrm{Al}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{As}

Tailored quantum dots for entangled photon pair creation

quantum wells have been measured by spin-beat spectroscopy based on a time-resolved Kerr rotation technique. The experimental data are plotted as functions of the lowest band-to-band optical transition energy, i.e., the effective band gap of the quantum wells. The model calculations suggest that in the tracked range of transition energies

Resources of polarimetric sensitivity in spin noise spectroscopy

E

Anisotropy of electron and hole g-factors in (In,Ga)As quantum dots

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