Rostock 2019 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 60: Quantum Gases (Bosons and Fermions) II
Q 60.2: Talk
Friday, March 15, 2019, 11:00–11:15, S HS 037 Informatik
Imaging magnetic polarons in the doped Fermi-Hubbard model — •Joannis Koepsell1, Jayadev Vijayan1, Pimonpan Sompet1, Fabian Grusdt2,3, Timon Hilker1, Eugene Demler2, Guillaume Salomon1, Immanuel Bloch1,4, and Christian Gross1 — 1Max-Planck-Institut für Quantenoptik, 85748 Garching, Germany — 2Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA — 3Department of Physics, Technical University of Munich, 85748 Garching, Germany — 4Fakultät für Physik, Ludwig-Maximilians-Universität, 80799 München, Germany
Polarons are among the most fundamental quasiparticles emerging in interacting many-body systems, forming already at the level of a single mobile dopant. In the context of the two- dimensional Fermi-Hubbard model, such polarons are predicted to form around charged dopants in an antiferromagnetic background in the low doping regime close to the Mott insulating state. Here we report the microscopic observation of magnetic polarons in a doped Fermi-Hubbard system, harnessing the full single-site spin and density resolution of our ultracold-atom quantum simulator. We reveal the dressing of mobile doublons by a local reduction and even sign reversal of magnetic correlations, originating from the competition between kinetic and magnetic energy in the system. The experimentally observed polaron signatures are found to be consistent with an effective string model at finite temperature. We demonstrate that delocalization of the doublon is a necessary condition for polaron formation by contrasting this mobile setting to a scenario where the doublon is pinned to a lattice site.