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Mikhail M. Glazov - One of the best experts on this subject based on the ideXlab platform.
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Electron Spin noise under the conditions of nuclei-induced frequency focusing
Physical Review B, 2018Co-Authors: Natalie Jäschke, Frithjof B. Anders, Mikhail M. GlazovAbstract:We study theoretically the Electron Spin noise in quantum dots under non-equilibrium conditions caused by the pumping by a train of circularly polarized optical pulses. In such a situation, the nuclear Spins are known to adjust in such a way, that the Electron Spin precession frequencies become multiples of the pump pulse repetition frequency. This so called phase synchronization effect was uncovered in [Science {\bf 317}, 1896 (2007)] and termed nuclei-induced frequency focusing of Electron Spin coherence. Using the classical approach to the central Spin model we evaluate the nuclear Spin distribution function and the Electron Spin noise spectrum. We show that the Electron Spin noise spectrum consists of sharp peaks corresponding to the phase synchronization conditions and directly reveal the distribution of the nuclear Spins. We discuss the effects of nuclear Spin relaxation after the pumping is over and analyze the corresponding evolution of nuclear Spin distributions and Electron Spin noise spectra.
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Electron Spin synchronization induced by optical nuclear magnetic resonance feedback
Physical Review B, 2012Co-Authors: Mikhail M. Glazov, I. A. Yugova, Alexander L. EfrosAbstract:We predict a new physical mechanism explaining the Electron Spin precession frequency focusing effect observed recently in singly charged quantum dots exposed to a periodic train of resonant circularly polarized short optical pulses [A. Greilich et al, Science 317, 1896 (2007), Ref. 1]. We show that Electron Spin precession in an external magnetic field and a field of nuclei creates a Knight field oscillating at the frequency of nuclear Spin resonance. This field drives the projection of the nuclear Spin onto magnetic field to the value that makes the Electron Spin precession frequency a multiple of the train cyclic repetition frequency, which is the condition at which the Knight field vanishes.
Daniel Loss - One of the best experts on this subject based on the ideXlab platform.
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hyperfine interaction in a quantum dot non markovian Electron Spin dynamics
Physical Review B, 2004Co-Authors: W A Coish, Daniel LossAbstract:We have performed a systematic calculation for the non-Markovian dynamics of a localized Electron Spin interacting with an environment of nuclear Spins via the Fermi contact hyperfine interaction. This work applies to an Electron in the $s$-type orbital ground state of a quantum dot or bound to a donor impurity, and is valid for arbitrary polarization $p$ of the nuclear Spin system, and arbitrary nuclear Spin $I$ in high magnetic fields. In the limit of $p=1$ and $I=\frac{1}{2}$, the Born approximation of our perturbative theory recovers the exact Electron Spin dynamics. We have found the form of the generalized master equation (GME) for the longitudinal and transverse components of the Electron Spin to all orders in the Electron Spin-nuclear Spin flip-flop terms. Our perturbative expansion is regular, unlike standard time-dependent perturbation theory, and can be carried out to higher orders. We show this explicitly with a fourth-order calculation of the longitudinal Spin dynamics. In zero magnetic field, the fraction of the Electron Spin that decays is bounded by the smallness parameter $\ensuremath{\delta}=1∕{p}^{2}N$, where $N$ is the number of nuclear Spins within the extent of the Electron wave function. However, the form of the decay can only be determined in a high magnetic field, much larger than the maximum Overhauser field. In general the Electron Spin shows rich dynamics, described by a sum of contributions with nonexponential decay, exponential decay, and undamped oscillations. There is an abrupt crossover in the Electron Spin asymptotics at a critical dimensionality and shape of the Electron envelope wave function. We propose a scheme that could be used to measure the non-Markovian dynamics using a standard Spin-echo technique, even when the fraction that undergoes non-Markovian dynamics is small.
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hyperfine interaction in a quantum dot non markovian Electron Spin dynamics
Physical Review B, 2004Co-Authors: W A Coish, Daniel LossAbstract:We have performed a systematic calculation for the non-Markovian dynamics of a localized Electron Spin interacting with an environment of nuclear Spins via the Fermi contact hyperfine interaction. This work applies to an Electron in the s-type orbital ground state of a quantum dot or bound to a donor impurity, and is valid for arbitrary polarization p of the nuclear Spin system, and arbitrary nuclear Spin I in high magnetic fields. In the limit of p=1 and I=1/2, the Born approximation of our perturbative theory recovers the exact Electron Spin dynamics. We have found the form of the generalized master equation (GME) for the longitudinal and transverse components of the Electron Spin to all orders in the Electron Spin-nuclear Spin flip-flop terms. Our perturbative expansion is regular, unlike standard time-dependent perturbation theory, and can be carried out to higher orders. We show this explicitly with a fourth-order calculation of the longitudinal Spin dynamics. In zero magnetic field, the fraction of the Electron Spin that decays is bounded by the smallness parameter delta=1/p(2)N, where N is the number of nuclear Spins within the extent of the Electron wave function. However, the form of the decay can only be determined in a high magnetic field, much larger than the maximum Overhauser field. In general the Electron Spin shows rich dynamics, described by a sum of contributions with nonexponential decay, exponential decay, and undamped oscillations. There is an abrupt crossover in the Electron Spin asymptotics at a critical dimensionality and shape of the Electron envelope wave function. We propose a scheme that could be used to measure the non-Markovian dynamics using a standard Spin-echo technique, even when the fraction that undergoes non-Markovian dynamics is small.
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Optical detection of single-Electron Spin decoherence in a quantum dot
Physical Review B, 2004Co-Authors: Oliver Gywat, Hans-andreas Engel, Daniel Loss, Ryan Epstein, F. M. Mendoza, David D. AwschalomAbstract:We propose a method based on optically detected magnetic resonance (ODMR) to measure the decoherence time T-2 of a single Electron Spin in a semiconductor quantum dot. The Electron Spin resonance (ESR) of a single excess Electron on a quantum dot is probed by circularly polarized laser excitation. Due to Pauli blocking, optical excitation is only possible for one of the Electron-Spin states. The photoluminescence is modulated due to the ESR which enables the measurement of Electron-Spin decoherence. We study different possible schemes for such an ODMR setup.
Alexander L. Efros - One of the best experts on this subject based on the ideXlab platform.
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Electron Spin synchronization induced by optical nuclear magnetic resonance feedback
Physical Review B, 2012Co-Authors: Mikhail M. Glazov, I. A. Yugova, Alexander L. EfrosAbstract:We predict a new physical mechanism explaining the Electron Spin precession frequency focusing effect observed recently in singly charged quantum dots exposed to a periodic train of resonant circularly polarized short optical pulses [A. Greilich et al, Science 317, 1896 (2007), Ref. 1]. We show that Electron Spin precession in an external magnetic field and a field of nuclei creates a Knight field oscillating at the frequency of nuclear Spin resonance. This field drives the projection of the nuclear Spin onto magnetic field to the value that makes the Electron Spin precession frequency a multiple of the train cyclic repetition frequency, which is the condition at which the Knight field vanishes.
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Nuclei-Induced Frequency Focusing of Electron Spin Coherence
Science (New York N.Y.), 2007Co-Authors: Alex Greilich, I. A. Yugova, Alexander L. Efros, Andrew Shabaev, D. R. Yakovlev, Dirk Reuter, Andreas D. Wieck, Manfred BayerAbstract: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.
David D. Awschalom - One of the best experts on this subject based on the ideXlab platform.
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Optical detection of single-Electron Spin decoherence in a quantum dot
Physical Review B, 2004Co-Authors: Oliver Gywat, Hans-andreas Engel, Daniel Loss, Ryan Epstein, F. M. Mendoza, David D. AwschalomAbstract:We propose a method based on optically detected magnetic resonance (ODMR) to measure the decoherence time T-2 of a single Electron Spin in a semiconductor quantum dot. The Electron Spin resonance (ESR) of a single excess Electron on a quantum dot is probed by circularly polarized laser excitation. Due to Pauli blocking, optical excitation is only possible for one of the Electron-Spin states. The photoluminescence is modulated due to the ESR which enables the measurement of Electron-Spin decoherence. We study different possible schemes for such an ODMR setup.
Natalie Jäschke - One of the best experts on this subject based on the ideXlab platform.
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Electron Spin noise under the conditions of nuclei-induced frequency focusing
Physical Review B, 2018Co-Authors: Natalie Jäschke, Frithjof B. Anders, Mikhail M. GlazovAbstract:We study theoretically the Electron Spin noise in quantum dots under non-equilibrium conditions caused by the pumping by a train of circularly polarized optical pulses. In such a situation, the nuclear Spins are known to adjust in such a way, that the Electron Spin precession frequencies become multiples of the pump pulse repetition frequency. This so called phase synchronization effect was uncovered in [Science {\bf 317}, 1896 (2007)] and termed nuclei-induced frequency focusing of Electron Spin coherence. Using the classical approach to the central Spin model we evaluate the nuclear Spin distribution function and the Electron Spin noise spectrum. We show that the Electron Spin noise spectrum consists of sharp peaks corresponding to the phase synchronization conditions and directly reveal the distribution of the nuclear Spins. We discuss the effects of nuclear Spin relaxation after the pumping is over and analyze the corresponding evolution of nuclear Spin distributions and Electron Spin noise spectra.