The Experts below are selected from a list of 20289 Experts worldwide ranked by ideXlab platform
L Besombes - One of the best experts on this subject based on the ideXlab platform.
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Spin dynamics of an individual Cr atom in a Semiconductor Quantum Dot under optical excitation
Applied Physics Letters, 2016Co-Authors: Alban Lafuente-sampietro, H Boukari, H. Utsumi, Shinji Kuroda, L BesombesAbstract:We studied the spin dynamics of a Cr atom incorporated in a II-VI Semiconductor Quantum Dot using photon correlation techniques. We used recently developed singly Cr-doped CdTe/ZnTe Quantum Dots to access the spin of an individual magnetic atom. Auto-correlation of the photons emitted by the Quantum Dot under continuous wave optical excitation reveals fluctuations of the localized spin with a timescale in the 10 ns range. Cross-correlation gives quantitative transfer time between Cr spin states. A calculation of the time dependence of the spin levels population in Cr-doped Quantum Dots shows that the observed spin dynamics is dominated by the exciton-Cr interaction. These measurements also provide a lower bound in the 20 ns range for the intrinsic Cr spin relaxation time.
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Individual Cr atom in a Semiconductor Quantum Dot: Optical addressability and spin-strain coupling
Physical Review B: Condensed Matter and Materials Physics, 2016Co-Authors: Alban Lafuente-sampietro, H Boukari, H. Utsumi, Shinji Kuroda, L BesombesAbstract:We demonstrate the optical addressability of the spin of an individual chromium atom (Cr) embedded in a Semiconductor Quantum Dot. The emission of Cr-doped Quantum Dots and their evolution in magnetic field reveal a large magnetic anisotropy of the Cr spin induced by local strain. This results in the zero field splitting of the 0, ±1, and ±2 Cr spin states and in a thermalization on the magnetic ground states 0 and ±1. The observed strong spin to strain coupling of Cr is of particular interest for the development of hybrid spin-mechanical devices where coherent mechanical driving of an individual spin in an oscillator is needed. The magneto-optical properties of Cr-doped Quantum Dots are modeled by a spin Hamiltonian including the sensitivity of the Cr spin to the strain and the influence of the Quantum Dot symmetry on the carrier-Cr spin coupling.
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Spin dynamics of a Mn atom in a Semiconductor Quantum Dot under resonant optical excitation
Physical Review B: Condensed Matter and Materials Physics, 2013Co-Authors: Ségolène Jamet, H Boukari, L BesombesAbstract:We analyze the spin dynamics of an individual magnetic atom (Mn) inserted in a II-VI Semiconductor Quantum Dot under resonant optical excitation. In addition to standard optical pumping expected for a resonant excitation, we show that for particular conditions of laser detuning and excitation intensity, the spin population can be trapped in the state which is resonantly excited. This effect is modeled considering the coherent spin dynamics of the coupled electronic and nuclear spin of the Mn atom optically dressed by a resonant laser field. This spin population trapping mechanism is controlled by the combined effect of the coupling with the laser field and the coherent interaction between the different Mn spin states induced by an anisotropy of the strain in the plane of the Quantum Dot.
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optical spin orientation of a single manganese atom in a Semiconductor Quantum Dot using quasiresonant photoexcitation
Physical Review Letters, 2009Co-Authors: Le C Gall, R. Kolodka, L Besombes, H Boukari, J Cibert, H MarietteAbstract:An optical spin orientation is achieved for a Mn atom localized in a Semiconductor Quantum Dot using quasiresonant excitation at zero magnetic field. Optically created spin-polarized carriers generate an energy splitting of the Mn spin and enable magnetic moment orientation controlled by the photon helicity and energy. The dynamics and the magnetic field dependence of the optical pumping mechanism show that the spin lifetime of an isolated Mn atom at zero magnetic field is controlled by a magnetic anisotropy induced by the built-in strain in the Quantum Dots.
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Optical spin orientation of a single manganese atom in a Semiconductor Quantum Dot using quasi-resonant excitation
Physical Review Letters, 2009Co-Authors: Claire Le Gall, L Besombes, H Boukari, J Cibert, Roman Kolodka, H MarietteAbstract:An optical spin orientation is achieved for a Mn atom localized in a Semiconductor Quantum Dot using quasiresonant excitation at zero magnetic field. Optically created spin-polarized carriers generate an energy splitting of the Mn spin and enable magnetic moment orientation controlled by the photon helicity and energy. The dynamics and the magnetic field dependence of the optical pumping mechanism show that the spin lifetime of an isolated Mn atom at zero magnetic field is controlled by a magnetic anisotropy induced by the built-in strain in the Quantum Dots.
Guillaume Cassabois - One of the best experts on this subject based on the ideXlab platform.
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From Random Telegraph to Gaussian Stochastic Noises: Decoherence and Spectral Diffusion in a Semiconductor Quantum Dot
Advances in Mathematical Physics, 2010Co-Authors: Alice Berthelot, Ph. Roussignol, Claude Delalande, R. Ferreira, Christophe Voisin, Guillaume CassaboisAbstract:We present a general theoretical description of the extrinsic dephasing mechanism of spectral diffusion that dominates the decoherence dynamics in Semiconductor Quantum Dots at low temperature. We discuss the limits of random telegraph and Gaussian stochastic noises and show that the combination of both approaches in the framework of the pre-Gaussian noise theory allows a quantitative interpretation of high-resolution experiments in single Semiconductor Quantum Dots. We emphasize the generality and the versatility of our model where the inclusion of asymmetric jump processes appears as an essential extension for the understanding of Semiconductor Quantum Dot physics.
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Voltage-controlled motional narrowing in a Semiconductor Quantum Dot
New Journal of Physics, 2009Co-Authors: Audrey Berthelot, R. Kolodka, Martin Hopkinson, Joanna Skiba-szymanska, Guillaume Cassabois, Ph. Roussignol, Claude Delalande, Alexander I. Tartakovskii, R. Ferreira, Christophe Voisin, M. S. SkolnickAbstract:We demonstrate the control with a dc voltage of the environment-induced\ndecoherence in a Semiconductor Quantum Dot (QD) embedded in a gated\nfield-effect device. The electrical control of the spectral diffusion\ndynamics governing the QD decoherence induces various effects, and\nin particular a narrowing of the QD emission spectrum on increasing\nthe electric field applied to the structure. We develop a model in\nthe framework of the pre-Gaussian noise theory that provides a quantitative\ninterpretation of our data as a function of gate voltage. The standard\nphenomenology of motional narrowing described in nuclear magnetic\nresonance is successfully reached by hastening the carrier escape\nfrom the traps around the QD through tunneling under reverse bias\nvoltage. Our study paves the way to a protection of zero-dimensional\nelectronic states from outside coupling through a voltage-controlled\nmotional narrowing effect., stark
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Dephasing processes in a single Semiconductor Quantum Dot
Comptes Rendus Physique, 2008Co-Authors: Guillaume Cassabois, R. FerreiraAbstract:We discuss the decoherence dynamics in a single Semiconductor Quantum Dot and analyze two dephasing mech- anisms. In the ¯rst part of the review, we examine the intrinsic source of dephasing provided by the coupling to acoustic phonons. We show that the non-perturbative reaction of the lattice to the interband optical transition results in a composite optical spectrum with a central zero-phonon line and lateral side-bands. In fact, these acoustic phonon side-bands completely dominate the Quantum Dot optical response at room temperature. In the second part of the paper, we focus on the extrinsic dephasing mechanism of spectral di®usion that determines the Quantum Dot decoherence at low temperatures. We interpret the variations of both width and shape of the zero- phonon line as due to the °uctuating electrostatic environment. In particular, we demonstrate the existence of a motional narrowing regime in the limit of low incident power or low temperature, thus revealing an unconventional phenomenology compared to nuclear magnetic resonance.
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Unconventional motional narrowing in a Semiconductor Quantum Dot
2007Co-Authors: Guillaume CassaboisAbstract:Motional narrowing refers to the striking phenomenon where the resonance line of a system coupled to a reservoir becomes narrower when increasing the reservoir fluctuation. I will present our recent data on the experimental evidence of motional narrowing in the optical spectrum of a Semiconductor Quantum Dot broadened by the spectral diffusion phenomenon [1]. Semiconductor Quantum Dots are often referred to as artificial atoms in solid state and the decoherence dynamics is a sensitive probe of the influence of the environment on the Quantum Dot optical and electronic properties. In fact, impurities, defects or localized charges in the vicinity of a Quantum Dot induce micro-electric fields that shift the Quantum Dot emission line through the Quantum confined Stark effect. The fluctuation of the Quantum Dot environment thus randomize the emission frequency and result in the so-called spectral diffusion effect. I will present the experimental evidence of a motional narrowing regime for the spectral diffusion of a single InAs/GaAs Quantum Dot. High-resolution Fourier-transform spectroscopy on the photoluminescence intensity of a single InAs/GaAs Quantum Dot brings the evidence of a crossover from Gaussian to Lorentzian line profiles on decreasing incident power or temperature. This observation shows that motional narrowing is surprisingly achieved on decreasing incident power or temperature, in contrast with the standard phenomenology observed for nuclear magnetic resonance. I will discuss some consequence of this non-standard type of motional narrowing on the dephasing dynamics in Semiconductor Quantum Dots [2]. [1] A. Berthelot, I. Favero, G. Cassabois, C. Voisin, C. Delalande, Ph. Roussignol, R. Ferreira, and J. M. G´erard, Nat. Phys. 2, 759 (2006). [2] I. Favero, A. Berthelot, G. Cassabois, C. Voisin, C. Delalande, Ph. Roussignol, R. Ferreira, and J. M. G´erard, Phys. Rev. B 75, 073308 (2007).
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unconventional motional narrowing in the optical spectrum of a Semiconductor Quantum Dot
Nature Physics, 2006Co-Authors: Alice Berthelot, Guillaume Cassabois, Ph. Roussignol, Claude Delalande, R. Ferreira, Christophe Voisin, Ivan Favero, Jeanmichel GerardAbstract:Motional narrowing refers to the striking phenomenon where the resonance line of a system coupled to a reservoir becomes narrower when increasing the reservoir fluctuation. A textbook example is found in nuclear magnetic resonance, where the fluctuating local magnetic fields created by randomly oriented nuclear spins are averaged when the motion of the nuclei is thermally activated. The existence of a motional narrowing effect in the optical response of Semiconductor Quantum Dots remains so far unexplored. This effect may be important in this instance since the decoherence dynamics is a central issue for the implementation of Quantum information processing based on Quantum Dots. Here we report on the experimental evidence of motional narrowing in the optical spectrum of a Semiconductor Quantum Dot broadened by the spectral diffusion phenomenon. Surprisingly, motional narrowing is achieved when decreasing incident power or temperature, in contrast with the standard phenomenology observed for nuclear magnetic resonance.
R. Ferreira - One of the best experts on this subject based on the ideXlab platform.
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From Random Telegraph to Gaussian Stochastic Noises: Decoherence and Spectral Diffusion in a Semiconductor Quantum Dot
Advances in Mathematical Physics, 2010Co-Authors: Alice Berthelot, Ph. Roussignol, Claude Delalande, R. Ferreira, Christophe Voisin, Guillaume CassaboisAbstract:We present a general theoretical description of the extrinsic dephasing mechanism of spectral diffusion that dominates the decoherence dynamics in Semiconductor Quantum Dots at low temperature. We discuss the limits of random telegraph and Gaussian stochastic noises and show that the combination of both approaches in the framework of the pre-Gaussian noise theory allows a quantitative interpretation of high-resolution experiments in single Semiconductor Quantum Dots. We emphasize the generality and the versatility of our model where the inclusion of asymmetric jump processes appears as an essential extension for the understanding of Semiconductor Quantum Dot physics.
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Voltage-controlled motional narrowing in a Semiconductor Quantum Dot
New Journal of Physics, 2009Co-Authors: Audrey Berthelot, R. Kolodka, Martin Hopkinson, Joanna Skiba-szymanska, Guillaume Cassabois, Ph. Roussignol, Claude Delalande, Alexander I. Tartakovskii, R. Ferreira, Christophe Voisin, M. S. SkolnickAbstract:We demonstrate the control with a dc voltage of the environment-induced\ndecoherence in a Semiconductor Quantum Dot (QD) embedded in a gated\nfield-effect device. The electrical control of the spectral diffusion\ndynamics governing the QD decoherence induces various effects, and\nin particular a narrowing of the QD emission spectrum on increasing\nthe electric field applied to the structure. We develop a model in\nthe framework of the pre-Gaussian noise theory that provides a quantitative\ninterpretation of our data as a function of gate voltage. The standard\nphenomenology of motional narrowing described in nuclear magnetic\nresonance is successfully reached by hastening the carrier escape\nfrom the traps around the QD through tunneling under reverse bias\nvoltage. Our study paves the way to a protection of zero-dimensional\nelectronic states from outside coupling through a voltage-controlled\nmotional narrowing effect., stark
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Dephasing processes in a single Semiconductor Quantum Dot
Comptes Rendus Physique, 2008Co-Authors: Guillaume Cassabois, R. FerreiraAbstract:We discuss the decoherence dynamics in a single Semiconductor Quantum Dot and analyze two dephasing mech- anisms. In the ¯rst part of the review, we examine the intrinsic source of dephasing provided by the coupling to acoustic phonons. We show that the non-perturbative reaction of the lattice to the interband optical transition results in a composite optical spectrum with a central zero-phonon line and lateral side-bands. In fact, these acoustic phonon side-bands completely dominate the Quantum Dot optical response at room temperature. In the second part of the paper, we focus on the extrinsic dephasing mechanism of spectral di®usion that determines the Quantum Dot decoherence at low temperatures. We interpret the variations of both width and shape of the zero- phonon line as due to the °uctuating electrostatic environment. In particular, we demonstrate the existence of a motional narrowing regime in the limit of low incident power or low temperature, thus revealing an unconventional phenomenology compared to nuclear magnetic resonance.
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unconventional motional narrowing in the optical spectrum of a Semiconductor Quantum Dot
Nature Physics, 2006Co-Authors: Alice Berthelot, Guillaume Cassabois, Ph. Roussignol, Claude Delalande, R. Ferreira, Christophe Voisin, Ivan Favero, Jeanmichel GerardAbstract:Motional narrowing refers to the striking phenomenon where the resonance line of a system coupled to a reservoir becomes narrower when increasing the reservoir fluctuation. A textbook example is found in nuclear magnetic resonance, where the fluctuating local magnetic fields created by randomly oriented nuclear spins are averaged when the motion of the nuclei is thermally activated. The existence of a motional narrowing effect in the optical response of Semiconductor Quantum Dots remains so far unexplored. This effect may be important in this instance since the decoherence dynamics is a central issue for the implementation of Quantum information processing based on Quantum Dots. Here we report on the experimental evidence of motional narrowing in the optical spectrum of a Semiconductor Quantum Dot broadened by the spectral diffusion phenomenon. Surprisingly, motional narrowing is achieved when decreasing incident power or temperature, in contrast with the standard phenomenology observed for nuclear magnetic resonance.
H Boukari - One of the best experts on this subject based on the ideXlab platform.
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Spin dynamics of an individual Cr atom in a Semiconductor Quantum Dot under optical excitation
Applied Physics Letters, 2016Co-Authors: Alban Lafuente-sampietro, H Boukari, H. Utsumi, Shinji Kuroda, L BesombesAbstract:We studied the spin dynamics of a Cr atom incorporated in a II-VI Semiconductor Quantum Dot using photon correlation techniques. We used recently developed singly Cr-doped CdTe/ZnTe Quantum Dots to access the spin of an individual magnetic atom. Auto-correlation of the photons emitted by the Quantum Dot under continuous wave optical excitation reveals fluctuations of the localized spin with a timescale in the 10 ns range. Cross-correlation gives quantitative transfer time between Cr spin states. A calculation of the time dependence of the spin levels population in Cr-doped Quantum Dots shows that the observed spin dynamics is dominated by the exciton-Cr interaction. These measurements also provide a lower bound in the 20 ns range for the intrinsic Cr spin relaxation time.
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Individual Cr atom in a Semiconductor Quantum Dot: Optical addressability and spin-strain coupling
Physical Review B: Condensed Matter and Materials Physics, 2016Co-Authors: Alban Lafuente-sampietro, H Boukari, H. Utsumi, Shinji Kuroda, L BesombesAbstract:We demonstrate the optical addressability of the spin of an individual chromium atom (Cr) embedded in a Semiconductor Quantum Dot. The emission of Cr-doped Quantum Dots and their evolution in magnetic field reveal a large magnetic anisotropy of the Cr spin induced by local strain. This results in the zero field splitting of the 0, ±1, and ±2 Cr spin states and in a thermalization on the magnetic ground states 0 and ±1. The observed strong spin to strain coupling of Cr is of particular interest for the development of hybrid spin-mechanical devices where coherent mechanical driving of an individual spin in an oscillator is needed. The magneto-optical properties of Cr-doped Quantum Dots are modeled by a spin Hamiltonian including the sensitivity of the Cr spin to the strain and the influence of the Quantum Dot symmetry on the carrier-Cr spin coupling.
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Spin dynamics of a Mn atom in a Semiconductor Quantum Dot under resonant optical excitation
Physical Review B: Condensed Matter and Materials Physics, 2013Co-Authors: Ségolène Jamet, H Boukari, L BesombesAbstract:We analyze the spin dynamics of an individual magnetic atom (Mn) inserted in a II-VI Semiconductor Quantum Dot under resonant optical excitation. In addition to standard optical pumping expected for a resonant excitation, we show that for particular conditions of laser detuning and excitation intensity, the spin population can be trapped in the state which is resonantly excited. This effect is modeled considering the coherent spin dynamics of the coupled electronic and nuclear spin of the Mn atom optically dressed by a resonant laser field. This spin population trapping mechanism is controlled by the combined effect of the coupling with the laser field and the coherent interaction between the different Mn spin states induced by an anisotropy of the strain in the plane of the Quantum Dot.
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optical spin orientation of a single manganese atom in a Semiconductor Quantum Dot using quasiresonant photoexcitation
Physical Review Letters, 2009Co-Authors: Le C Gall, R. Kolodka, L Besombes, H Boukari, J Cibert, H MarietteAbstract:An optical spin orientation is achieved for a Mn atom localized in a Semiconductor Quantum Dot using quasiresonant excitation at zero magnetic field. Optically created spin-polarized carriers generate an energy splitting of the Mn spin and enable magnetic moment orientation controlled by the photon helicity and energy. The dynamics and the magnetic field dependence of the optical pumping mechanism show that the spin lifetime of an isolated Mn atom at zero magnetic field is controlled by a magnetic anisotropy induced by the built-in strain in the Quantum Dots.
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Optical spin orientation of a single manganese atom in a Semiconductor Quantum Dot using quasi-resonant excitation
Physical Review Letters, 2009Co-Authors: Claire Le Gall, L Besombes, H Boukari, J Cibert, Roman Kolodka, H MarietteAbstract:An optical spin orientation is achieved for a Mn atom localized in a Semiconductor Quantum Dot using quasiresonant excitation at zero magnetic field. Optically created spin-polarized carriers generate an energy splitting of the Mn spin and enable magnetic moment orientation controlled by the photon helicity and energy. The dynamics and the magnetic field dependence of the optical pumping mechanism show that the spin lifetime of an isolated Mn atom at zero magnetic field is controlled by a magnetic anisotropy induced by the built-in strain in the Quantum Dots.
H Mariette - One of the best experts on this subject based on the ideXlab platform.
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optical spin orientation of a single manganese atom in a Semiconductor Quantum Dot using quasiresonant photoexcitation
Physical Review Letters, 2009Co-Authors: Le C Gall, R. Kolodka, L Besombes, H Boukari, J Cibert, H MarietteAbstract:An optical spin orientation is achieved for a Mn atom localized in a Semiconductor Quantum Dot using quasiresonant excitation at zero magnetic field. Optically created spin-polarized carriers generate an energy splitting of the Mn spin and enable magnetic moment orientation controlled by the photon helicity and energy. The dynamics and the magnetic field dependence of the optical pumping mechanism show that the spin lifetime of an isolated Mn atom at zero magnetic field is controlled by a magnetic anisotropy induced by the built-in strain in the Quantum Dots.
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Optical spin orientation of a single manganese atom in a Semiconductor Quantum Dot using quasi-resonant excitation
Physical Review Letters, 2009Co-Authors: Claire Le Gall, L Besombes, H Boukari, J Cibert, Roman Kolodka, H MarietteAbstract:An optical spin orientation is achieved for a Mn atom localized in a Semiconductor Quantum Dot using quasiresonant excitation at zero magnetic field. Optically created spin-polarized carriers generate an energy splitting of the Mn spin and enable magnetic moment orientation controlled by the photon helicity and energy. The dynamics and the magnetic field dependence of the optical pumping mechanism show that the spin lifetime of an isolated Mn atom at zero magnetic field is controlled by a magnetic anisotropy induced by the built-in strain in the Quantum Dots.
