Berlin 2012 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 30: Matter At Low Temperature: Quantum Liquids, Bose-Einstein Condensates, Ultra-cold Atoms, ... 1
TT 30.3: Vortrag
Mittwoch, 28. März 2012, 15:45–16:00, H 3005
Universal probes for antiferromagnetic correlations and entropy in cold fermions on optical lattices — •E.V. Gorelik1, D. Rost1, T. Paiva2, R. Scalettar3, A. Klümper4, and N. Blümer1 — 1Institute of Physics, Johannes Gutenberg University, Mainz, Germany — 2Instituto de Fisica, Universidade Federal do Rio de Janeiro, Brazil — 3Department of Physics, UC Davis, USA — 4University of Wuppertal, Germany
A major hurdle on the way of using ultracold fermionic atoms on optical lattices as “quantum simulators” of correlated solids is the verification of antiferromagnetic (AF) signatures. Current experimental efforts focus on nearest-neighbor (NN) spin correlation functions and on cooling below a central entropy per site of s<log(2)/2.
Our calculations in the strong-coupling regime of the half-filled Hubbard model using DMFT, determinantal QMC, and Bethe ansatz [1] reveal AF signatures in the double occupancy, spin correlations, and kinetic energy already at s≲log(2) with surprising universality regarding dimensionality, when viewed as a function of entropy (which is appropriate in the cold-atom context). Both the onset of next-nearest neighbor spin correlations and a minimum in the double occupancy clearly separate the AF Heisenberg regime (at s≲log(2)) from dominant charge physics and should be used experimentally to probe both the AF correlations and the entropy of the system.
E. V. Gorelik, D. Rost, T. Paiva, R. Scalettar, A. Klümper, N. Blümer, arXiv:1105.3356