Speaker
Dmitry Abanin
Description
We are used to describing systems of many particles by
statistical mechanics. However, recently it was realized that
the basic postulate of statistical mechanics – ergodicity --
breaks down in so-called many-body localized systems,
where disorder prevents particle transport and
thermalization. In this talk, I will describe a theory of the
many-body localized (MBL) phase, based on new insights
from quantum entanglement. I will argue that, in contrast to
ergodic systems, MBL eigenstates are not highly entangled,
but rather obey so-called area law, typical of ground states in
gapped systems. I will use this fact to show that MBL phase
is characterized by an infinite number of emergent local
conservation laws, in terms of which the Hamiltonian acquires
a universal form. Turning to the experimental implications, I
will show that MBL systems exhibit a universal response to
quantum quenches: surprisingly, entanglement shows
logarithmic in time growth, reminiscent of glasses, while local
observables exhibit power-law approach to “equilibrium”
values. I will also introduce a criterion for the transition
between many-body localized and ergodic phases, based on
the response of the system to a local perturbation.
