Dresden 2017 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 17: Spintronics II (joined session with TT)
HL 17.5: Vortrag
Montag, 20. März 2017, 16:15–16:30, POT 151
Higher-order quantum theory of spin noise spectroscopy — •Daniel Hägele — Spektroskopie der kondensierten Materie, Ruhr-Universität Bochum, D-44780 Bochum
Spin noise spectroscopy has recently evolved into a versatile tool for studying spin dynamics in atoms and solids with minimal perturbation of the quantum system. A fully quantum mechanical theory of the detector output z(t) is highly desirable for calculating higher order spectra of complex spin systems taking into account measurement back-action and relaxation. Treating spin noise spectroscopy within a stochastic master equation approach we find z(t) in all orders of the measurement strength β [1]. This continuous quantum noise formula (CQNF) depends non-linearly on the equilibrium density matrix ρ0 and contains as further ingredients the system propagator G(t), the measurement operator σz, and multiple convolutions with white Gaussian noise Γ(t). The CQNF allows for a systematic derivation of the spin noise spectrum Sq(ω) = 1/2(Tr[ (σz − Tr(σz ρ0))G(ω)(σzρ0 + ρ0 σz)] + c.c.) and higher order spectra such as the bispectum and trispectrum. The CQNF may also be applied to transport theory and measurement theory in general.
[1] D. Hägele, https://arxiv.org/abs/1611.02077