The Experts below are selected from a list of 16674 Experts worldwide ranked by ideXlab platform
Paola Cappellaro - One of the best experts on this subject based on the ideXlab platform.
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measurement of transverse Hyperfine Interaction by forbidden transitions
Physical Review B, 2015Co-Authors: Mo Chen, Masashi Hirose, Paola CappellaroAbstract:Precise characterization of a system's Hamiltonian is crucial to its high-fidelity control that would enable many quantum technologies, ranging from quantum computation to communication and sensing. In particular, nonsecular parts of the Hamiltonian are usually more difficult to characterize, even if they can give rise to subtle but non-negligible effects. Here we present a strategy for the precise estimation of the transverse Hyperfine coupling between an electronic and a nuclear spin, exploiting effects due to nominally forbidden transitions during the Rabi nutation of the nuclear spin. We applied the method to precisely determine the transverse coupling between a nitrogen-vacancy center electronic spin and its nitrogen nuclear spin. In addition, we show how this transverse Hyperfine coupling, which has been often neglected in experiments, is crucial to achieving large enhancements of the nuclear Rabi nutation rate.
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measurement of transverse Hyperfine Interaction by forbidden transitions
Physical Review Letters, 2015Co-Authors: Mo Chen, Masashi Hirose, Paola CappellaroAbstract:(Received 14 April 2015; revised manuscript received 21 May 2015; published 6 July 2015) Precise characterization of a system’s Hamiltonian is crucial to its high-fidelity control that would enable many quantum technologies, ranging from quantum computation to communication and sensing. In particular, nonsecular parts of the Hamiltonian are usually more difficult to characterize, even if they can give rise to subtle but non-negligible effects. Here we present a strategy for the precise estimation of the transverse Hyperfine coupling between an electronic and a nuclear spin, exploiting effects due to nominally forbidden transitions during the Rabi nutation of the nuclear spin. We applied the method to precisely determine the transverse coupling between a nitrogen-vacancy center electronic spin and its nitrogen nuclear spin. In addition, we show how this transverse Hyperfine coupling, which has been often neglected in experiments, is crucial to achieving large enhancements of the nuclear Rabi nutation rate.
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Measurement of transverse Hyperfine Interaction by forbidden transitions
Physical Review B - Condensed Matter and Materials Physics, 2015Co-Authors: Mo Chen, Masashi Hirose, Paola CappellaroAbstract:Precise characterization of a system's Hamiltonian is crucial to its high-fidelity control that would enable many quantum technologies, ranging from quantum computation to communication and sensing. In particular, non-secular parts of the Hamiltonian are usually more difficult to characterize, even if they can give rise to subtle but non-negligible effects. Here we present a strategy for the precise estimation of the transverse Hyperfine coupling between an electronic and a nuclear spin, exploiting effects due to forbidden transitions during the Rabi driving of the nuclear spin. We applied the method to precisely determine the transverse coupling between a Nitrogen-Vacancy center electronic spin and its Nitrogen nuclear spin. In addition, we show how this transverse Hyperfine, that has been often neglected in experiments, is crucial to achieving large enhancements of the nuclear Rabi driving.
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=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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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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electron spin dynamics in quantum dots and related nanostructures due to Hyperfine Interaction with nuclei
arXiv: Mesoscale and Nanoscale Physics, 2003Co-Authors: John Schliemann, Alexander Khaetskii, Daniel LossAbstract:We review and summarize recent theoretical and experimental work on electron spin dynamics in quantum dots and related nanostructures due to Hyperfine Interaction with surrounding nuclear spins. This topic is of particular interest with respect to several proposals for quantum information processing in solid state systems. Specifically, we investigate the Hyperfine Interaction of an electron spin confined in a quantum dot in an s-type conduction band with the nuclear spins in the dot. This Interaction is proportional to the square modulus of the electron wave function at the location of each nucleus leading to an inhomogeneous coupling, i.e. nuclei in different locations are coupled with different strength. In the case of an initially fully polarized nuclear spin system an exact analytical solution for the spin dynamics can be found. For not completely polarized nuclei, approximation-free results can only be obtained numerically in sufficiently small systems. We compare these exact results with findings from several approximation strategies.
Benoît Eble - One of the best experts on this subject based on the ideXlab platform.
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hole spin initialization in quantum dots by a periodic train of short pulses
Journal of Physics: Conference Series, 2010Co-Authors: Benoît Eble, Pascal Desfonds, Christophe Testelin, Maria Chamarro, F. Fras, Audrey Miard, Frédéric Bernardot, Aristide LemaîtreAbstract:We model pump-probe experiments leading to the all-optical initialization of the hole spin of a p-doped InAs/GaAs quantum dots ensemble. We consider selection rules of mixed hole states and include periodic excitation conditions. Hyperfine Interaction is taken into account as the common decoherence mechanism for the spins of electrons and holes. We show that the degree of hole spin polarization can be maximized by quenching the action of the hole Hyperfine Interaction with a small applied magnetic field. However additional hole spin relaxation mechanisms, in the microsecond time range, determine the absolute value of this maximum.
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Hole-spin dephasing time associated with Hyperfine Interaction in quantum dots
Physical Review B : Condensed matter and materials physics, 2009Co-Authors: Christophe Testelin, Benoît Eble, Frédéric Bernardot, Maria ChamarroAbstract:The spin Interaction of a hole confined in a quantum dot with the surrounding nuclei is described in terms of an effective magnetic field. We show that, in contrast to the Fermi contact Hyperfine Interaction for conduction electrons, the dipole-dipole Hyperfine Interaction is anisotropic for a hole, for both pure or mixed hole states. We evaluate the coupling constants of the hole-nuclear Interaction and demonstrate that they are only 1 order of magnitude smaller than the coupling constants of the electron-nuclear Interaction. We also study, theoretically, the hole-spin dephasing of an ensemble of quantum dots via the Hyperfine Interaction in the framework of frozen fluctuations of the nuclear field, in the absence or in the presence of an applied magnetic field. We also discuss experiments which could evidence the dipole-dipole Hyperfine Interaction and give information on hole mixing.
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Hyperfine Interaction in inas gaas self assembled quantum dots dynamical nuclear polarization versus spin relaxation
Comptes Rendus Physique, 2008Co-Authors: O Krebs, Benoît Eble, A Lemaitre, P Voisin, B Urbaszek, T Amand, X MarieAbstract:Abstract We report on the influence of the Hyperfine Interaction on the optical orientation of singly charged excitons X ± in self-assembled InAs/GaAs quantum dots. All measurements were carried out on individual quantum dots studied by micro-photoluminescence at low temperature. We show that the Hyperfine Interaction leads to an effective partial spin relaxation, under 50 kHz modulated excitation polarization, which becomes, however, strongly inhibited under steady optical pumping conditions because of dynamical nuclear polarization. This optically created magnetic-like nuclear field can become very strong (up to ∼ 4 T ) when it is generated in the direction opposite to a longitudinally applied field, and exhibits then a bistability regime. This effect is very well described by a theoretical model derived in a perturbative approach, which reveals the key role played by the energy cost of an electron spin flip in the total magnetic field. Finally, we emphasize the similarities and differences between X + and X − trions with respect to the Hyperfine Interaction, which turn out to be in perfect agreement with the theoretical description. To cite this article: O. Krebs et al., C. R. Physique 9 (2008).
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Role of Hyperfine Interaction on electron spin optical orientation in charge-controlled InAs-GaAs single quantum dots
physica status solidi (a), 2007Co-Authors: O Krebs, Benoît Eble, A Lemaitre, B Urbaszek, K. Kowalik, A. Kudelski, Xavier Marie, Thierry Amand, P VoisinAbstract:We report on electron spin physics in a single charge-tunable self-assembled InAs/GaAs quantum dot. The Hyperfine Interaction between the optically oriented electron and nuclear spins leads to the polarization of the quantum dot nuclei. The sign of the resulting Overhauser-shift depends on the trion state X+ or X, and remarkably its strength does not vanish in zero magnetic field. This explains the quenching of X+ spin relaxation under steady-state excitation polarization. (c) 2007 WILEYNCH Verlag GmbH & Co. KGaA, Weinheim.
Frederic Merkt - One of the best experts on this subject based on the ideXlab platform.
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Hyperfine Interaction induced g u mixing and its implication on the existence of the first excited vibrational level of the a σu 2 state of h2 and on the scattering length of the h h collision
Journal of Chemical Physics, 2018Co-Authors: Maximilian Beyer, Frederic MerktAbstract:Ab initio calculations of the energy level structure of H2+ that include relativistic and radiative corrections to nonrelativistic energies and the diagonal part of the Hyperfine Interaction have predicted the existence of four bound rovibrational levels [(v = 0, N = 0 − 2) and (v = 1, N = 0)] of the first electronically excited (A+ Σu+2) state of H2+, the (v = 1, N = 0) level having a calculated binding energy of only Eb = 1.082 219 8(4)·10−9 Eh and leading to an extremely large scattering length of 750(5) a0 for the H+ + H collision [J. Carbonell et al., J. Phys. B: At., Mol. Opt. Phys. 37, 2997 (2004)]. We present an investigation of the nonadiabatic coupling between the first two electronic states (X+ Σg+2 and A+ Σu+2) of H2+ induced by the Fermi-contact term of the Hyperfine-coupling Hamiltonian. This Interaction term, which mixes states of total spin quantum number G = 1/2, is rigorously implemented in a close-coupling approach to solve the spin-rovibronic Schrodinger equation. We show that it mixes states of gerade and ungerade electronic symmetry, that it shifts the positions of all weakly bound rovibrational states of H2+, and that it affects both the positions and widths of its shape resonances. The calculations demonstrate that the G = 1/2 Hyperfine component of the A+ (v = 1, N = 0) state does not exist and that, for G = 1/2, the s-wave scattering lengths of the H+ + H(1s) collision are −578(6) a0 and −43(4) a0 for the F = 0 and F = 1 Hyperfine components of the H(1s) atom, respectively. The binding energy of the G = 3/2 Hyperfine component of the A+ (v = 1, N = 0) state is not significantly affected by the Hyperfine Interaction and the corresponding scattering length for the H+ + H(1s, F = 1) collision is 757(7) a0.Ab initio calculations of the energy level structure of H2+ that include relativistic and radiative corrections to nonrelativistic energies and the diagonal part of the Hyperfine Interaction have predicted the existence of four bound rovibrational levels [(v = 0, N = 0 − 2) and (v = 1, N = 0)] of the first electronically excited (A+ Σu+2) state of H2+, the (v = 1, N = 0) level having a calculated binding energy of only Eb = 1.082 219 8(4)·10−9 Eh and leading to an extremely large scattering length of 750(5) a0 for the H+ + H collision [J. Carbonell et al., J. Phys. B: At., Mol. Opt. Phys. 37, 2997 (2004)]. We present an investigation of the nonadiabatic coupling between the first two electronic states (X+ Σg+2 and A+ Σu+2) of H2+ induced by the Fermi-contact term of the Hyperfine-coupling Hamiltonian. This Interaction term, which mixes states of total spin quantum number G = 1/2, is rigorously implemented in a close-coupling approach to solve the spin-rovibronic Schrodinger equation. We show that it mixes...
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Hyperfine Interaction induced g u mixing and its implication on the existence of the first excited vibrational level of the a σu 2 state of h2 and on the scattering length of the h h collision
Journal of Chemical Physics, 2018Co-Authors: Maximilian Beyer, Frederic MerktAbstract:Ab initio calculations of the energy level structure of H2+ that include relativistic and radiative corrections to nonrelativistic energies and the diagonal part of the Hyperfine Interaction have predicted the existence of four bound rovibrational levels [(v = 0, N = 0 - 2) and (v = 1, N = 0)] of the first electronically excited ( A+ Σu+2 ) state of H2+ , the (v = 1, N = 0) level having a calculated binding energy of only Eb = 1.082 219 8(4)·10-9 Eh and leading to an extremely large scattering length of 750(5) a0 for the H+ + H collision [J. Carbonell et al., J. Phys. B: At., Mol. Opt. Phys. 37, 2997 (2004)]. We present an investigation of the nonadiabatic coupling between the first two electronic states ( X+ Σg+2 and A+ Σu+2 ) of H2+ induced by the Fermi-contact term of the Hyperfine-coupling Hamiltonian. This Interaction term, which mixes states of total spin quantum number G = 1/2, is rigorously implemented in a close-coupling approach to solve the spin-rovibronic Schrodinger equation. We show that it mixes states of gerade and ungerade electronic symmetry, that it shifts the positions of all weakly bound rovibrational states of H2+ , and that it affects both the positions and widths of its shape resonances. The calculations demonstrate that the G = 1/2 Hyperfine component of the A+ (v = 1, N = 0) state does not exist and that, for G = 1/2, the s-wave scattering lengths of the H+ + H(1s) collision are -578(6) a0 and -43(4) a0 for the F = 0 and F = 1 Hyperfine components of the H(1s) atom, respectively. The binding energy of the G = 3/2 Hyperfine component of the A+ (v = 1, N = 0) state is not significantly affected by the Hyperfine Interaction and the corresponding scattering length for the H+ + H(1s, F = 1) collision is 757(7) a0.
K W Kim - One of the best experts on this subject based on the ideXlab platform.
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effect of an external magnetic field on electron spin dephasing induced by Hyperfine Interaction in quantum dots
Physical Review B, 2003Co-Authors: Y G Semenov, K W KimAbstract:We investigate the influence of an external magnetic field on spin-phase relaxation of single electrons in semiconductor quantum dots induced by the Hyperfine Interaction. The basic decay mechanism is attributed to the dispersion of local effective nuclear fields over the ensemble of quantum dots. The characteristics of electron-spin dephasing are analyzed by taking an average over the nuclear-spin distribution. We find that the dephasing rate can be estimated as a spin-precession frequency caused primarily by the mean value of the local nuclear magnetic field. Furthermore, it is shown that the Hyperfine Interaction does not fully depolarize electron spin. The loss of initial spin polarization during the dephasing process depends strongly on the external magnetic field, leading to the possibility of effective suppression of this mechanism.
