Enhanced superexchange in a tilted mott insulator

Dimitrova, Ivana and Jepsen, Niklas and Buyskikh, Anton and Venegas-Gomez, Araceli and Amato-Grill, Jesse and Daley, Andrew and Ketterle, Wolfgang (2020) Enhanced superexchange in a tilted mott insulator. Physical Review Letters, 124 (4). 043204. ISSN 1079-7114 (https://doi.org/10.1103/PhysRevLett.124.043204)

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In an optical lattice, entropy and mass transport by first-order tunneling are much faster than spin transport via superexchange. Here we show that adding a constant force (tilt) suppresses first-order tunneling, but not spin transport, realizing new features for spin Hamiltonians. Suppression of the superfluid transition can stabilize larger systems with faster spin dynamics. For the first time in a many-body spin system, we vary superexchange rates by over a factor of 100 and tune spin-spin interactions via the tilt. In a tilted lattice, defects are immobile and pure spin dynamics can be studied.