Floquet-Anderson localization in the Thouless pump and how to avoid it

Rövid cím: 
Floquet-Anderson localization in the Thouless pump
2024. 02. 23. 10:15
BME building F, seminar room of the Dept. of Theoretical Physics
János Asbóth (BME/Wigner)
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