Quantum Matter Seminar
Note: This event will be a virtual seminar please see the zoom link below:
Well-controlled synthetic quantum systems, such as ultracold atoms in optical
lattices, offer intriguing possibilities to study complex many-body problems relevant
to a variety of research areas. In particular, out-of-equilibrium phenomena constitute
natural applications of quantum simulators, which have already successfully
demonstrated simulations in regimes that are beyond reach using state-of-the-art
numerical techniques. While generic models are expected to thermalize according to
the eigenstate thermalization hypothesis (ETH), violation of ETH is believed to occur
mainly in two types of systems: integrable models and many-body localized systems
(MBL). In between these two extreme limits there is, however, a whole range of
models that exhibit more complex dynamics.
The 1D tilted Fermi-Hubbard model has emerged as a versatile platform to study a
rich variety of weak ergodic-breaking phenomena in a clean system without disorder.
We have realized this model with fermionic K-atoms and observed a surprisingly
robust memory of the initial state over a wide range of parameters , which we
explain via emergent kinetic constraints. Our measurements were performed in
systems of about 290 lattice sites for up to 700 tunneling times - a regime that is
currently not accessible with state-of-the-art numerical techniques. We have used
these results to benchmark a novel more efficient numerical technique . Moreover,
in the large-tilt regime the observed non-ergodic behavior is explained by an
emergent fragmentation of the many-body Hilbert space into an exponential number
of dynamically disconnected subspaces . The experimental realization of this
regime paves the way for future studies at the interface of MBL and weak-ergodicity
breaking phenomena in one- and two-dimensions.
 S. Scherg et al., Nat. Comm. 12, 4490 (2021).
 B. Hebbe Madhusudhana et al., arXiv:2105.06372, to appear in PRX Quantum.
 T. Kohlert et al., arXiv:2106.15586 (2021).