ELFT HÍRADÓ

[Janos Asboth <asboth.janos AT ttk.bme.hu>]

Meghívó

BME Elméleti Fizika Szeminárium,

febr. 23. péntek 10h15,

1111 Budapest, Budafoki út 8., BME F III. magasföldszint 01.,
Elméleti Fizika Tanszék szemináriumi szoba

Asbóth János (BME TTK Elm. Fiz. tanszék, Wigner FK Kvantumoptikai és
Kvantuminformatikai Osztály):
Floquet-Anderson localization in the Thouless pump and how to avoid it

We investigated numerically how onsite disorder affects conduction in the
periodically driven Rice-Mele model, a prototypical realization of the
Thouless pump. Although the pump is robust against disorder in the fully
adiabatic limit, much less is known about the case of finite period time T,
which is relevant also in light of recent experimental realizations. We
found [1] that at any fixed period time and nonzero disorder, increasing
the system size L→∞ always leads to a breakdown of the pump, indicating
Anderson localization of the Floquet states. Our numerics indicate,
however, that in a properly defined thermodynamic limit, where L/T^θ is
kept constant, Anderson localization can be avoided, and the charge pumped
per cycle has a well-defined value – as long as the disorder is not too
strong. The critical exponent θ is not universal, rather, its value depends
on the disorder strength. Our findings are relevant for practical,
experimental realizations of the Thouless pump, for studies investigating
the nature of its current-carrying Floquet eigenstates, as well as the
mechanism of the full breakdown of the pump, expected if the disorder
exceeds a critical value.

[1] A Grabarits, A Takacs, IC Fulga, and JK Asboth,  arXiv:2309.12882

Minden érdeklődőt szeretettel várunk.
Asbóth János,
 szemináriumi koordinátor