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IQIM Postdoctoral and Graduate Student Seminar

Friday, October 19, 2018
12:00pm to 1:00pm
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East Bridge 114
Avoiding Ergodicity: Static and Dynamical Localization in Clean Interacting Systems
Yuval Baum, IQIM Postdoctoral Scholar, Refael Group,

Abstract: Since the phenomenon of many-body-localization (MBL) was re-postulated more than a decade ago, it has attracted a great deal of attention. A key ingredient for achieving the MBL phase is disorder
(randomness). The roots of this phase lie within the phenomenon of Anderson localization, where non-interacting particles form a localized non-ergodic phase. It is the question regarding the fate
of Anderson localization in the presence of interactions that plants the seed for the discovery of the MBL phase.

We wish to go beyond the conventional paradigm and ask whether randomness is indeed an essential ingredient in achieving generic non-ergodic interacting phases. We proposed the idea that the
essential ingredient for MBL is localization, which does not necessarily mean disorder. We analyze the spectral and the dynamical properties of one-dimensional interacting fermions and spins in the
presence of both disorder and linear potential. We show that by considering these two di fferent localizing mechanisms, i.e., disorder and linear fi elds, one may construct a two-dimensional phase
diagram which hosts a connected non-ergodic (MBL) phase.

We also examine the eff ect of periodic driving on the dynamics of many-body systems and show how such driving provides a general framework for controlling the transport properties in the sys-
tem, as well establish mobile composite particles. We demonstrate that by including successive driving terms, it is possible to completely suppress the motion of particles, and e ectively localize
the many-body system, without the presence of any form of disorder.

1. Y. Baum, Evert P. L. van Nieuwenburg and Gil Refael, "From Dynamical Localization to Bunching in interacting Floquet Systems", SciPost Phys. 5, 017 (2018).
2. Evert P. L. van Nieuwenburg, Y. Baum and Gil Refael, "From Bloch Oscillations to Many Body Localization in Clean Interacting Systems", arXiv:1808.00471 (2018).

For more information, please contact Marcia Brown by phone at 626-395-4013 or by email at [email protected].