Wydział Fizyki i Informatyki Stosowanej
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2018-04-06 18.04. wykład prof. E. Shermana o informacji w szumie spinowym

Szanowni Państwo,
Zapraszamy na wykład prof. E. Shermana z Uniwersytetu Kraju Basków, pt.

How informative is spin noise spectrum? .

Wykład odbędzie się w środę 18.04 w sali D/D10 o 17:10 (45 min+dyskusja)

Poniżej streszczenie referatu

Spin-noise spectroscopy became one of the most powerful tools in studies of spin- related effects in solids [1]. Spectrum of the spin noise contains valuable info about collective and memory-related effects in spin fluctuations near the equilibrium. Here we present theoretical results on the spin noise spectroscopy for electrons in nanowires and for polaritons in semiconductor microcavites. First, we present a theory of spin noise in semiconductor nanowires considered as prospective elements for spintronics and studies of the Majorana states. In these structures, spin-orbit coupling can be realized as a random function of a coordinate correlated on a spatial scale of the order of 10 nm. By analyzing different regimes of electron transport and spin dynamics, we demonstrate that the spin relaxation can be very slow, and the resulting noise power spectrum increases algebraically as the frequency goes to zero [2]. Next, we study theoretically the spin decoherence and intrinsic spin noise caused by an interplay of electron hopping between localized states and the hyperfine interaction of electron and nuclear spins. At a sufficiently low density of localization sites the hopping rates have an exponentially broad distribution. This broadness permits the description of the spin dynamics in terms of closely situated “pairs” of sites and single “reaching” states, from which the series of hops result in electron localization inside a “pair.” Somewhat similar to the case of the random spin-orbit coupling, the results demonstrate disorder-dependent algebraic tails in the spin decay and power-law singularities in the low-frequency part of the spectrum [3]. Next, we present a theory of spin fluctuations of exciton polaritons in a pumped semiconductor microcavity. The corresponding spin noise is sensitive to the scattering processes in the system, occupation of the ground state, statistics of polaritons, and interactions. Its spectrum drastically narrows in the polariton lasing regime due to formation of a polariton condensate, and the shape becomes non-Lorentzian owing to interaction-induced spin decoherence [4].

[1] J. Hubner, F. Berski, R. Dahbashi, and M. Oestreich, Physica Status Solidi (b) 251, 1824 (2014)
[2] M. M. Glazov and E. Ya. Sherman, Phys. Rev. Lett. 107, 156602 (2011)
[3] A. V. Shumilin, E. Ya. Sherman, and M. M. Glazov, Phys. Rev. B 94, 125305 (2016)
[4] M. M. Glazov, M. A. Semina, E. Ya. Sherman, and A. V. Kavokin, Phys. Rev. B 88, 041309(R) (2013)

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