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Walking hand in hand. Two-body quantum dynamics in excitronics

Giovedì 5 aprile 2018, ore 15.00, aula Seminari, S3 Cnr Nano, terzo piano, edificio Fisica, Dipartimento FIM, Modena

Relatore: Prof. Guido Goldoni (Unimore)

Abstract: Spatially indirect excitons (IXs) are optically excited electron-hole pairs with the two charges kept separated in different layers of a planar heterostructure. Since recombination is strongly suppressed, IXs may be accelerated and travel in-plane long distances before light emission is induced on-demand. Hence, excitonic circuits are all-optical devices which may elaborate information without the need to commute between light and charge.
While single-particle scattering is a textbook topic in quantum mechanics, two-body scattering is not. IXs undergo a complex dynamic when propagating, say, in the potential landscape of excitonic transistors. Although scattering of correlated quantum particles is common also in quantum chemistry or nuclear reactions, literature is very recent, and modelling is usually based on mean-field methods.
In this talk I will discuss exact Schrödinger propagation of Coulomb bound eletron-hole pairs, simulating coherent transport of IXs in several classes of in-plane static and time-varying scattering potentials – wells/barriers, single/double slits, dots/antidots, harmonic – using the Split-Step Fourier method, which fully takes into account the two-body dynamics of the pair. Even when a weak scattering potential cannot induce internal transitions or dissociation of the pair, dynamic correlations cause 1) renormalization of transmission resonances, 2) strongly enhanced tunneling, 3) diffraction fringes where mean-field scattering would predict none. These correlation effects can be accounted for by the phase shifts induced by internal virtual transitions during the scattering process. Elaborating on this idea, we demonstrate a new beyond-mean-field, self-energy approach, with orders of magnitude reduction in numerical load, but insignificant loss of accuracy for low energy scattering.
Few-body scattering is a fundamental, yet little studied topic. Hence, we propose that excitonic devices might prove an ideal playground to test models of correlation.

The seminar slides will be available here http://www.nano.cnr.it after the talk.
Please check the complete list of NANO Seminar here .

[Ultimo aggiornamento: 04/04/2018 11:50:35]