Bulletin of the American Physical Society
APS March Meeting 2017
Volume 62, Number 4
Monday–Friday, March 13–17, 2017; New Orleans, Louisiana
Session R19: Novel Magnetism and Correlated States in Ultracold Atomic SystemsInvited
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Sponsoring Units: DAMOP Room: 278-279 |
Thursday, March 16, 2017 8:00AM - 8:36AM |
R19.00001: Spatial Charge and Spin Correlations in the Fermi-Hubbard Model Invited Speaker: Martin Zwierlein Strong electron correlations lie at the origin of transformative phenomena such as colossal magneto-resistance and high-temperature superconductivity. Already near room temperature, doped copper oxide materials display remarkable features such as a pseudo-gap and a "strange metal" phase with unusual transport properties. The essence of this physics is believed to be captured by the Fermi-Hubbard model of repulsively interacting, itinerant fermions on a lattice. I will describe our recent experiments on two-dimensional Fermi gases of $^{40}$K atoms under a Fermi gas microscope [1], where metallic, Mott insulating and band insulating states of the Fermi-Hubbard model were observed with single-site, single-atom resolution [2]. The microscope allows for the site-resolved observation of charge and spin correlations in this system [3]. It directly reveals anti-ferromagnetic spin correlations, the Pauli and correlation hole in the metallic regions, and strong doublon-hole bunching in the region near half-filling. The latter is expected in the presence of singlet bonds forming between adjacent lattice sites and should play an important role for transport in the Fermi-Hubbard model.\\ \\$[1]$ Lawrence W. Cheuk, Matthew A. Nichols, Melih Okan, Thomas Gersdorf, Vinay V. Ramasesh, Waseem S. Bakr, Thomas Lompe, Martin W. Zwierlein, Phys. Rev. Lett. 114, 193001 (2015).\newline [2] Lawrence W. Cheuk, Matthew A. Nichols, Katherine R. Lawrence, Melih Okan, Hao Zhang, Martin W. Zwierlein, Phys. Rev. Lett. 116, 235301 (2016).\newline [3] Lawrence W. Cheuk, Matthew A. Nichols, Katherine R. Lawrence, Melih Okan, Hao Zhang, Ehsan Khatami, Nandini Trivedi, Thereza Paiva, Marcos Rigol, Martin W. Zwierlein, Science 353, 1260-1264 (2016) [Preview Abstract] |
Thursday, March 16, 2017 8:36AM - 9:12AM |
R19.00002: Quantum magnetism with highly magnetic atoms Invited Speaker: Bruno Laburthe-Tolra We experimentally investigate many-body spin dynamics associated to the interaction of many spins coupled by dipole-dipole interactions. The experiment is performed using a Chromium Bose-Einstein condensate loaded into a 3D optical lattice. We excite the spin state of the each of the atoms uniformly across the lattice, and we study spin dynamics after this excitation procedure. Spin dynamics is primarily driven by inter-site dipole-dipole interactions. As each atom is coupled to many neighbors, the dynamics is intrinsically driven by many-body effects. We specifically study the conditions in which spin-spin quantum correlations may arise in the lattice, i.e. the conditions in which magnetism can be considered as quantum, in contrast to classical magnetism. I will present our latest experimental results as a function of the lattice depth, and as a function of how the spins are excited in the lattice. [Preview Abstract] |
Thursday, March 16, 2017 9:12AM - 9:48AM |
R19.00003: Exploring antiferromagnetic correlations of ultracold atoms in two dimensions Invited Speaker: Ferdinand Brennecke Near zero temperature, quantum magnetism can non-trivially arise from short-range interactions, however the occurrence of magnetic order depends crucially on the interplay of interactions, lattice geometry, dimensionality and doping. Ultracold atomic Fermi gases in optical lattices constitute an experimental system with unrivalled tunability and detection capabilities to explore quantum magnetism by analog quantum simulation. In this talk I will present our recent experimental studies of the emergence of antiferromagnetic correlations between ultracold fermionic $^{40}$K atoms in two dimensions with decreasing temperature. We determine the magnetic susceptibility of the Hubbard model from simultaneous measurements of the in-situ density of both spin components. At half-filling and strong interactions our data approach the Heisenberg model of localized spins with antiferromagnetic correlations. When the system is doped away from half-filling, we observe the disappearance of magnetic correlations. Our observation of the dependence of quantum magnetism on doping paves the way for future studies on the emergence of pseudogap and pairing phenomena away from half-filling. [Preview Abstract] |
Thursday, March 16, 2017 9:48AM - 10:24AM |
R19.00004: Site-resolved observations of antiferromagnetic correlations in the Hubbard model Invited Speaker: Markus Greiner |
Thursday, March 16, 2017 10:24AM - 11:00AM |
R19.00005: Exploring quantum magnetism at the single spin and atom level Invited Speaker: Christian Gross Quantum gas microscopes enable the single spin resolved observation and manipulation of ultracold atoms in optical lattices. This powerful tool provides access to novel observables for the characterization of tailored many-body systems. We report on progress on the study of one dimensional ultracold Fermions in an optical lattice, for which we recently observed antiferromagnetic correlations at half filling and persisting strong string correlations, connecting to hidden string order at zero temperature, for lower filling. Furthermore, we report on collapse and revival dynamics of the transverse magnetization of long-range interacting Ising spins. The long-range interaction potential of soft-core shape was induced by weak dressing to Rydberg states. This demonstrates that strong tailored interaction potentials can be induced by Rydberg dressing, which preserve the coherent evolution of the many-body system. [Preview Abstract] |
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