SCL Seminar by Suzana Miladić

You are cordially invited to the SCL seminar of the Center for the Study of Complex Systems, which will be held on Thursday, 31 October 2019 at 14:00 in the library reading room “Dr. Dragan Popović" of the Institute of Physics Belgrade. The talk entitled

Electric dipole spin resonance and phonon-induced relaxation in InSb nanowire quantum dots

will be given by Suzana Miladić (PhD student, Faculty of Physics, University of Belgrade). Abstract of the talk:

One of possible physical realizations of a qubit (basic unit of quantum information) are spin states of electrons trapped in a semiconductor nanowire quantum dot. The spin qubit states are realized by the Zeeman interaction of trapped electrons with an external magnetic field. At low temperatures, the possibility of transitions between qubit states induced by thermal effects can be neglected and qubit are well isolated. On the other hand, the effects that arise from the fact that electrons are in a semiconductor, such as spin-orbit interaction (SOI), have to be considered.

In this talk we will address the above problem using a Hamiltonian of an electron in a semiconductor nanowire quantum dot, which includes two perturbations, namely Zeeman and SOI. We will use a finite difference method adapted and tested on model gating potentials. Our analysis reveals significant effect of the SOI on qubit states. The interplay of Zeeman and SOI is described by an effective Lande g-factor, which shows a periodic anisotropy corresponding to the magnetic field direction relative to the spin-orbit field. The presence of the SOI can be exploited for control of qubit states by an ac electric field, but it also opens a possibility for unwanted transitions due to interaction of electrons with lattice phonons (relaxation). Our results show dependence of the Rabi frequency on the magnetic field direction and its strength, and also on the SOI strength. Similar results are also obtained for the relaxation rate. We have performed such an analysis for two model potentials (harmonic potential and an infinite square well) and demonstrated that the Rabi frequency and the relaxation rate also depend on the shape of gating potential.

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