Spin Noise Spectroscopy on Zero-Dimensional Semiconductor Nanostructures
Final Report Abstract
The primary aim of this project was the investigation of the spin dynamics of single quantum dots, with a particular focus on heavy-hole spins under different conditions of temperature, external magnetic fields, and electrical fields. The initial studies did not focus directly on quantum dots but rather on the spin relaxation dynamics of partially localized electrons in n-type GaAs. This research led to the development of a comprehensive theoretical model regarding the spin dynamics of charge carriers in a strongly interacting environment with incomplete localization. The theoretical model provides an excellent description of the experimental data and predicts inter alia that the maximum achievable electron spin relaxation time in n-type GaAs is approximately one microsecond in the absence of significant external magnetic fields. Interestingly, this maximum does not occur at the lowest temperature but at an optimum finite temperature. In a second step, optical spin noise spectroscopy was applied to single, positively charged (In,Ga)As quantum dots emitting in the telecom C-band. The experiments revealed details concerning hole-spin relaxation times and Auger recombination processes in these potentially technologically relevant quantum dots. In a third step, hole spin relaxation at high magnetic fields was studied in standard (In,Ga)As quantum dots. At high magnetic fields, spin and charge dynamics are to some extent decoupled and the Faraday fluctuation signal of the Zeeman-split resonances becomes more complex. The further development of spin noise theory including these extreme parameters revealed, inter alia, that the laser-induced photoelectric effect dominates the charge loss of the quantum dot, which is an important factor for photonic quantum applications that rely on optical readout. In a last step, time-resolved resonance fluorescence and single photon detection was used to investigate with high resolution correlations between charge and spin noise. The technique allowed the identification of Stark-shifted resonances and the recording of complex charge dynamics of adjacent Si impurity sites. Temporally varying Stark shifts, smaller than the homogeneous linewidth of the quantum dot exciton and trion transitions, were resolved by evaluation of the photon statistics. Extremely fast Auger processes were identified by a characteristic background in the time-resolved resonance fluorescence signal. The understanding of these complex charge dynamics is crucial to enhancing the stability, reliability, and application of QDs in quantum technologies.
Publications
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Doping and temperature dependence of nuclear spin relaxation in-type GaAs. Physical Review B, 102(23).
Abaspour, L.; Sterin, P.; Rugeramigabo, E. P.; Hübner, J. & Oestreich, M.
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Non-equilibrium spin noise spectroscopy of a single quantum dot operating at fiber telecommunication wavelengths. Journal of Applied Physics, 131(6).
Sun, Tian-Jiao; Sterin, P.; Lengert, L.; Nawrath, C.; Jetter, M.; Michler, P.; Ji, Yang; Hübner, J. & Oestreich, M.
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Temperature-dependent electron spin relaxation at the metal-to-insulator transition in n-type GaAs. Physical Review B, 106(12).
Sterin, P.; Abaspour, L.; Lonnemann, J. G.; Rugeramigabo, E. P.; Hübner, J. & Oestreich, M.
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"Homodyne spin noise spectroscopy and noise spectroscopy of a single quantum dot", Dissertation, Leibniz Universität Hannover, 2023
P. Sterin
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Two-way photoeffectlike occupancy dynamics in a single (InGa)As quantum dot. Physical Review B, 108(12).
Sterin, Pavel; Hühn, Kai; Glazov, Mikhail M.; Hübner, Jens & Oestreich, Michael
