Collective nuclear stabilization in single quantum dots by noncollinear hyperfine interaction

Yang, Wen; Sham, L. J.

doi:10.1103/physrevb.85.235319

Cited by 26 publications

(61 citation statements)

References 38 publications

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“…2(b), initially proposed by Xu et al 75 and subsequently explored by our previous study, 80 that established the mechanism of holeinduced nuclear spin flip with a preferential direction through the noncollinear dipolar hyperfine interaction. This feedback loop serves as an excellent example for our general theory because it can realize all the interesting regimes discussed above.…”

Section: Systematic Microscopic Theory For General Feedback Loopmentioning

confidence: 82%

“…(ii) The anisotropic hole-nuclear dipolar hyperfine interaction, 66,68,75,80,[83][84][85] whose dominant part is diagonal ∝Ŝ h,zÎz . Heavy-light hole mixing [86][87][88] introduces a smaller off-diagonal part ∝Ŝ h,+Î− +Ŝ h,−Î+ and an even smaller …”

Section: B General Feedback Processes Between Electron Hole and Numentioning

confidence: 99%

“…1(b)], our previous study 80 established the mechanism of holeinduced nuclear spin flip with a preferential direction through the noncollinear dipolar hyperfine interaction [wavy arrow in Fig. 1(b)].…”

Section: Theoretical Treatment Of Nuclear Field Back Actionmentioning

confidence: 99%

“…3(a)] closes the feedback loop. Our previous solution 80 for a specific feedback loop [ Fig. 1(b)] is designed for a specific Hamiltonian.…”

Section: -5mentioning

confidence: 99%

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General theory of feedback control of a nuclear spin ensemble in quantum dots

Yang

Sham

2013

Phys. Rev. B

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We present a microscopic theory of the nonequilibrium nuclear spin dynamics driven by the electron and/or hole under continuous-wave pumping in a quantum dot. We show the correlated dynamics of the nuclear spin ensemble and the electron and/or hole under optical excitation as a quantum feedback loop and investigate the dynamics of the many nuclear spins as a nonlinear collective motion. This gives rise to three observable effects: (i) hysteresis, (ii) locking (avoidance) of the pump absorption strength to (from) the natural resonance, and (iii) suppression (amplification) of the fluctuation of weakly polarized nuclear spins, leading to prolonged (shortened) electron-spin coherence time. A single nonlinear feedback function is constructed which determines the different outcomes of the three effects listed above depending on the feedback being negative or positive. The general theory also helps to put in perspective the wide range of existing theories on the problem of a single electron spin in a nuclear spin bath.

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Section: Systematic Microscopic Theory For General Feedback Loopmentioning

confidence: 82%

Section: B General Feedback Processes Between Electron Hole and Numentioning

confidence: 99%

Section: Theoretical Treatment Of Nuclear Field Back Actionmentioning

confidence: 99%

“…3(a)] closes the feedback loop. Our previous solution 80 for a specific feedback loop [ Fig. 1(b)] is designed for a specific Hamiltonian.…”

Section: -5mentioning

confidence: 99%

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General theory of feedback control of a nuclear spin ensemble in quantum dots

Yang

Sham

2013

Phys. Rev. B

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“…The effect known as dragging (anti-dragging) occurs when the electron-spin causes the nuclear-spins to align in such a way as to Zeeman-shift the transition into (out of) resonance with the incident light [31,32]. This effect is particularly pronounced at high magnetic fields, long integration times, and when the step-size of the laser frequency sweep is small.…”

mentioning

confidence: 99%

Optical Thermometry of an Electron Reservoir Coupled to a Single Quantum Dot in the Millikelvin Range

et al. 2014

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We show how resonant laser spectroscopy of the trion optical transitions in a self-assembled quantum dot can be used to determine the temperature of a nearby electron reservoir. At finite magnetic field the spin-state occupation of the Zeeman-split quantum dot electron ground states is governed by thermalization with the electron reservoir via co-tunneling. With resonant spectroscopy of the corresponding excited trion states we map out the spin occupation as a function of magnetic field to establish optical thermometry for the electron reservoir. We demonstrate the implementation of the technique in the sub-Kelvin temperature range where it is most sensitive, and where the electron temperature is not necessarily given by the cryostat base temperature.Self-assembled semiconductor quantum dots (QDs) represent promising building blocks for quantum information processing [1], and more recently have emerged as an intriguing model system for optical studies of the quantum impurity problem -the interaction of a localized electron with the continuum of states in a fermionic reservoir [2]. In the regime of strong tunnel coupling of a resident QD electron to the nearby Fermi sea and sufficiently low temperatures, signatures of many-body phenomena are observable in emission [3] or absorption with power-law tails characteristic of the Fermi-edge singularity [4] and the Kondo effect [5] in resonant spectra of neutral and singly charged QDs. In addition to resonant laser spectroscopy of charge-tunable QDs [6] and the control of their exchange coupling to the Fermi reservoir enabled by the gate voltage in QD field-effect devices [7], related experiments crucially require cryogenic temperatures deep in the sub-Kelvin regime [4,5].While the temperature of the electron reservoir is a key parameter in exploiting many-body phenomena, it is not necessarily the same as that of the cryogenic bath, and is difficult to access directly. In this Letter, we present a spectroscopic method to determine the electron bath temperature. Our technique exploits the sensitivity of spin-selective optical absorption in singly charged QDs [8-10] to temperature. A measurement of the effective QD electron spin temperature can be directly related to the spin bath temperature of the Fermi reservoir [11][12][13]. Although the QD-bath temperature relationship is complicated by optical spin pumping (OSP), in the limit of strong exchange coupling between the QD spin and the Fermi bath via co-tunneling, the OSP is negligible, and the QD spin state occupation is entirely governed by the thermal distribution of the electrons in the Fermi sea. In either case (with or without OSP), the QD electron spin polarization measured as a function of an external magnetic field provides a direct measure of the electron bath temperature.In our experiment we used self-assembled InGaAs quantum dots grown by molecular beam epitaxy [14] with intermediate annealing [15]. The QDs were embedded inside a field effect device [16] where a 25 nm thick GaAs tunneling barrier separates th...

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Discretization of the total magnetic field by the nuclear spin bath in fluorine-doped ZnSe

et al. 2018

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The coherent spin dynamics of fluorine donor-bound electrons in ZnSe induced by pulsed optical excitation is studied in a perpendicular applied magnetic field. The Larmor precession frequency serves as a measure for the total magnetic field exerted onto the electron spins and, surprisingly, does not increase linearly with the applied field, but shows a step-like behavior with pronounced plateaus, given by multiples of the laser repetition rate. This discretization occurs by a feedback mechanism in which the electron spins polarize the nuclear spins, which in turn generate a local Overhauser field adjusting the total magnetic field accordingly. Varying the optical excitation power, we can control the plateaus, in agreement with our theoretical model. From this model, we trace the observed discretization to the optically induced Stark field, which causes the dynamic nuclear polarization.

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Collective nuclear stabilization in single quantum dots by noncollinear hyperfine interaction

Cited by 26 publications

References 38 publications

General theory of feedback control of a nuclear spin ensemble in quantum dots

General theory of feedback control of a nuclear spin ensemble in quantum dots

Optical Thermometry of an Electron Reservoir Coupled to a Single Quantum Dot in the Millikelvin Range

Discretization of the total magnetic field by the nuclear spin bath in fluorine-doped ZnSe

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