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We report measurements of the time for spin flip from dark (non-light emitting) exciton states in quantum dots to bright (light emitting) exciton states in InP quantum dots. Dark excitons are created by two-photon excitation by an ultrafast…

Condensed Matter · Physics 2009-11-10 D. W. Snoke , J. Huebner , W. W. Ruehle , M. Zundel

Exciton luminescence of a CdSe quantum dot (QD) inserted in a ZnSe nanowire is strongly influenced by the dark exciton states. Because of the small size of these QDs (2-5nm), exchange interaction between hole and electron is highly enhanced…

We demonstrate a new method of measuring the exciton spin relaxation time in semiconductor nanostructures by continuous-wave photoluminescence. We find that for self-assembled CdTe quantum dots the degree of circular polarization of…

Materials Science · Physics 2009-11-10 S. Mackowski , T. A. Nguyen , H. E. Jackson , L. M. Smith , J. Kossut , G. Karczewski

We analyze time-resolved spontaneous emission from excitons confined in self-assembled $\mathrm{InAs}$ quantum dots placed at various distances to a semiconductor-air interface. The modification of the local density of optical states due to…

Other Condensed Matter · Physics 2010-11-05 Søren Stobbe , Jeppe Johansen , Philip Trøst Kristensen , Jørn M. Hvam , Peter Lodahl

The population dynamics of dark and bright excitons in (In,Ga)As/GaAs quantum dots is studied by two-color pump-probe spectroscopy in an external magnetic field. With the field applied in Faraday geometry and at T<20 K, the dark excitons…

Mesoscale and Nanoscale Physics · Physics 2012-05-08 H. Kurtze , D. R. Yakovlev , D. Reuter , A. D. Wieck , M. Bayer

Exciton spin dynamics in quasi-spherical CdS quantum dots is studied in detail experimentally and theoretically. Exciton states are calculated using the 6-band k.p Hamiltonian. It is shown that for various sets of Luttinger parameters, when…

Materials Science · Physics 2015-05-14 P. Horodyska , P. Nemec , D. Sprinzl , P. Maly , V. N. Gladilin , J. T. Devreese

Photoluminescence of a single CdSe quantum dot embedded in a ZnSe nanowire has been investigated. It has been found that the dark exciton has a strong influence on the optical properties. The most visible influence is the strongly reduced…

Using background-free detection of spin-state-dependent resonance fluorescence from a single-electron charged quantum dot with an efficiency of 0:1%, we realize a single spin-photon interface where the detection of a scattered photon with…

Mesoscale and Nanoscale Physics · Physics 2015-05-18 S. T. Yilmaz , P. Fallahi , A. Imamoglu

We demonstrate the selective coupling of a single quantum dot exciton spin state with the cavity mode in a quantum dot-micropillar cavity system. By tuning an external magnetic field, the Zeeman splitted exciton spin states coupled…

We derive a rigorous theory of the interaction between photons and spatially extended excitons confined in quantum dots in inhomogeneous photonic materials. We show that, beyond the dipole approximation, the radiative decay rate is…

Mesoscale and Nanoscale Physics · Physics 2012-08-10 Søren Stobbe , Philip T. Kristensen , Jakob E. Mortensen , Jørn M. Hvam , Jesper Mørk , Peter Lodahl

We report optical pumping of neutral quantum dots leading to nuclear spin alignment with direction insensitive to polarization and wavelength of light. Measurements of photoluminescence of both "dark" and "bright" excitons in single dots…

Mesoscale and Nanoscale Physics · Physics 2011-04-05 E. A. Chekhovich , A. B. Krysa , M. S. Skolnick , A. I. Tartakovskii

The mechanisms of energy and spin transfer in quantum dot pairs coupled via the Coulomb interaction are studied. Exciton transfer can be resonant or phonon-assisted. In both cases, the transfer rates strongly depend on the resonance…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 Alexander O. Govorov

Exciton spin relaxation is investigated in single epitaxially grown semiconductor quantum dots in order to test the expected spin relaxation quenching in this system. We study the polarization anisotropy of the photoluminescence signal…

We investigate theoretically the spin splitting of the exciton states in semiconductor coupled quantum dots (CQDs) containing a single magnetic ion. We find that the spin splitting can be switched on/off in the CQDs \textit{via} the…

Materials Science · Physics 2009-11-13 Xiaojing Li , Kai Chang

A semiconductor quantum dot (QD) is an attractive resource to generate polarization-entangled photon pairs. We study the excitonic spin precession (flip-flop) in a family of QDs with different excitonic fine-structure splitting (FSS) and…

We investigate spin-flip processes of Si quantum dots due to spin-orbit coupling. We utilize the spin-orbit coupling constants related to bulk and structure inversion asymmetry obtained numerically for two dimensional heterostructures. We…

Mesoscale and Nanoscale Physics · Physics 2015-05-13 M. Prada , R. H. Blick , R. Joynt

We use the spin-polarized excitons in a single quantum dot to design optical controls for basic operations in quantum computing. We examine the ultrafast nonlinear optical processes required and use the coherent nonlinear optical responses…

Mesoscale and Nanoscale Physics · Physics 2009-10-31 Pochung Chen , C. Piermarocchi , L. J. Sham

Electron-hole exchange interactions split the exciton ground state into "dark" and "bright" states. The dynamics of those states depends on the internal relaxation time between bright and dark states (spin-flip time), and on the radiative…

Materials Science · Physics 2009-11-11 Gustavo A. Narvaez , Gabriel Bester , Alberto Franceschetti , Alex Zunger

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

The band structure of type-I (In,Al)As/AlAs quantum dots with band gap energy exceeding 1.63 eV is indirect in momentum space, leading to long-lived exciton states with potential applications in quantum information. Optical access to these…

Mesoscale and Nanoscale Physics · Physics 2015-06-19 J. Debus , T. S. Shamirzaev , D. Dunker , V. F. Sapega , E. L. Ivchenko , D. R. Yakovlev , A. I. Toropov , M. Bayer
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