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Correlation between the rectilinear polarisations of the photons emitted from the biexciton decay in a single quantum dot is investigated in a device which allows the charge-state of the dot to be controlled. Optimising emission from the…

Quantum Physics · Physics 2009-11-13 R. J. Young , S. J. Dewhurst , R. M. Stevenson , A. J. Shields , P. Atkinson , K. Cooper , D. A. Ritchie

We investigate exciton spin memory in individual InAs/GaAs self-assembled quantum dots via optical alignment and conversion of exciton polarization in a magnetic field. Quasiresonant phonon-assisted excitation is successfully employed to…

Materials Science · Physics 2009-11-13 K. Kowalik , O. Krebs , A. Lemaître , J. A. Gaj , P. Voisin

We present a microscopic theory of optical initialization, control and detection for a single electron spin in a quantum dot embedded into a zero-dimensional microcavity. The strong coupling regime of the trion and the cavity mode is…

Mesoscale and Nanoscale Physics · Physics 2015-09-23 D. S. Smirnov , M. M. Glazov , E. L. Ivchenko , L. Lanco

Quantum control of solid-state spin qubits typically involves pulses in the microwave domain, drawing from the well-developed toolbox of magnetic resonance spectroscopy. Driving a solid-state spin by optical means offers a high-speed…

We demonstrate that the quantum dot-confined dark exciton forms a long-lived integer spin solid state qubit which can be deterministically on-demand initiated in a pure state by one optical pulse. Moreover, we show that this qubit can be…

Quantum Physics · Physics 2015-03-05 I. Schwartz , E. R. Schmidgall , L. Gantz , D. Cogan , E. Bordo , Y. Don , M. Zielinski , D. Gershoni

We demonstrate optical control of the polarization eigenstates of a neutral quantum dot exciton without any external fields. By varying the excitation power of a circularly polarized laser in micro-photoluminescence experiments on…

A potential scheme is proposed for realizing a two-qubit quantum gate in semiconductor quantum dots. Information is encoded in the spin degrees of freedom of one excess conduction electron of each quantum dot. We propose to use two lasers,…

Quantum Physics · Physics 2009-11-10 Mang Feng , Irene D'Amico , Paolo Zanardi , Fausto Rossi

We study the phonon-induced dephasing of the exciton state in a quantum dot excited by a sequence of ultra-short pulses. We show that the multiple-pulse control leads to a considerable improvement of the coherence of the optically excited…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 V. M. Axt , P. Machnikowski , T. Kuhn

We investigate the spin-dependent dynamical response of a quantum ring with a spin-orbit interaction upon the application of linearly polarized, picosecond, asymmetric electromagnetic pulses. The oscillations of the generated dipole moment…

Mesoscale and Nanoscale Physics · Physics 2009-11-13 Zhen-Gang Zhu , Jamal Berakdar

We propose to use optical detection of magnetic resonance (ODMR) to measure the decoherence time T_{2} of a single electron spin in a semiconductor quantum dot. The electron is in one of the spin 1/2 states and a circularly polarized laser…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Oliver Gywat , Hans-Andreas Engel , Daniel Loss

A Cr atom in a semiconductor host carries a localized spin with an intrinsic large spin to strain coupling particularly promising for the development of hybrid spin-mechanical systems and coherent mechanical spin driving. We demonstrate…

Mesoscale and Nanoscale Physics · Physics 2017-02-01 A. Lafuente-Sampietro , H. Utsumi , H. Boukari , S. Kuroda , L. Besombes

We investigate the spin-resolved electron dynamics in a double quantum dot driven by ultrafast asymmetric electromagnetic pulses. Using a analytical model we show that applying an appropriate pulse sequence allows to control coherently the…

Mesoscale and Nanoscale Physics · Physics 2017-02-15 J. Waetzel , A. S. Moskalenko , J. Berakdar

We study the exciton spin relaxation in CdTe self-assembled quantum dots by using polarized photoluminescence spectroscopy in magnetic field. The experiments on single CdTe quantum dots and on large quantum dot ensembles show that by…

The four-level exciton/biexciton system of a single semiconductor quantum dot acts as a two qubit register. We experimentally demonstrate an exciton-biexciton Rabi rotation conditional on the initial exciton spin in a single InGaAs/GaAs…

Mesoscale and Nanoscale Physics · Physics 2009-11-13 S. J. Boyle , A. J. Ramsay , F. Bello , H. Y. Liu , M. Hopkinson , A. M. Fox , M. S. Skolnick

We first predict the splitting of a spin degenerate impurity level when this impurity is irradiated by a circularly polarized laser beam tuned in the transparency region of a semiconductor. This splitting, which comes from different…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 M. Combescot , O. Betbeder-Matibet

Coherent manipulation of quantum bits (qubits) on time scales much shorter than the coherence time is a key prerequisite for quantum information processing. Electron spins in quantum dots (QDs) are particularly attractive for…

Mesoscale and Nanoscale Physics · Physics 2011-10-03 A. Greilich , Sophia E. Economou , S. Spatzek , D. R. Yakovlev , D. Reuter , A. D. Wieck , T. L. Reinecke , M. Bayer

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…

A two-photon process leading to coherent transitions between the two circularly polarized exciton states in a quantum dot is studied. It is shown that optical flipping of the exciton polarization is possible with picosecond laser pulses.…

Mesoscale and Nanoscale Physics · Physics 2007-10-24 P. Machnikowski

Optical control of the spin coherence of quantum well electrons by short laser pulses with circular or linear polarization is studied experimentally and theoretically. For that purpose the coherent electron spin dynamics in a n-doped…

Mesoscale and Nanoscale Physics · Physics 2010-09-15 E. A. Zhukov , D. R. Yakovlev , M. M. Glazov , L. Fokina , G. Karczewski , T. Wojtowicz , J. Kossut , M. Bayer

The rotational response of quantum condensed fluids is strikingly distinct from rotating classical fluids, especially notable for the excitation and ordering of quantized vortex ensembles. Although widely studied in conservative systems,…