74,314 research outputs found

    Theory of anisotropic exchange in laterally coupled quantum dots

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    The effects of spin-orbit coupling on the two-electron spectra in lateral coupled quantum dots are investigated analytically and numerically. It is demonstrated that in the absence of magnetic field the exchange interaction is practically unaffected by spin-orbit coupling, for any interdot coupling, boosting prospects for spin-based quantum computing. The anisotropic exchange appears at finite magnetic fields. A numerically accurate effective spin Hamiltonian for modeling spin-orbit-induced two-electron spin dynamics in the presence of magnetic field is proposed.Comment: 4 pages, 3 figures; paper rewritte

    Self-sustained magnetoelectric oscillations in magnetic resonant tunneling structures

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    The dynamic interplay of transport, electrostatic, and magnetic effects in the resonant tunneling through ferromagnetic quantum wells is theoretically investigated. It is shown that the carrier-mediated magnetic order in the ferromagnetic region not only induces, but also takes part in intrinsic, robust, and sustainable high-frequency current oscillations over a large window of nominally steady bias voltages. This phenomenon could spawn a new class of quantum electronic devices based on ferromagnetic semiconductors.Comment: 5 pages, 4 figure

    Recent progress in the partial-wave analysis of the diffractively produced ππ+π\pi^-\pi^+\pi^- final state at COMPASS

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    The COMPASS spectrometer at CERN has collected a large data set for diffractive three-pion production of 46×10646\times10^6 exclusive events. Based on previous conventional Partial-Wave Analyses (PWA), we performed a `freed-isobar PWA' on the same data, removing model assumptions on the dynamic isobar amplitudes for dominating waves. In this analysis, we encountered continuous mathematical ambiguities, which we were able to identify and resolve. This analysis gives an unprecedented insight in the interplay of 2π2\pi and 3π3\pi dynamics in the process. As an example we show results for a spin-exotic wave JXPC=1+J^{PC}_{X^-}=1^{-+} wave.Comment: Proceedings for the 15th International Workshop on Meson Physics (MESON 2018) from June 7th to 12th 2018 in Krak\'ow, Poland. Five pages, four figure
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