ELFT HÍRADÓ

[mcsete AT physx.u-szeged.hu]

Seminar

Speaker: Dr. János Asbóth, associate professor & senior research fellow
(BME TTK, Department of Theoretical Physics & HUN-REN Wigner Research  
Center for Physics, Quantum Optics and Quantum Information Department)

Date: 1 pm, 06, June (Thursday) 2024
Location: SZTE TTIK FI, Bay Zoltan class-room & online
https://join.skype.com/zfxvAFEnu0Ay

The title of presentation:
Floquet-Anderson localization in the Thouless pump and how to avoid it

Short abstract of the presentation:
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^? 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 ? 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, Phys. Rev. B 109,  
L180202 (2024)

Everyone is welcome to attend.

Dr. Mária Csete


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