CMSA Topological Quantum Matter Seminar: Exact Results in Flat Band Hubbard Models


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September 20, 2023 10:30 am - 11:30 am
CMSA, 20 Garden St, G10
Address: 20 Garden Street, Cambridge, MA 02138

Jonah Herzog-Arbeitman - Princeton University

Flat bands, like those in the kagome lattice or twisted bilayer graphene, are a
natural setting for studying strongly coupled physics since the interaction
strength is the only energy scale in the problem. They can exhibit
unconventional behavior in the multi-orbital case: the mean-field theory of
flat band attractive Hubbard models shows the possibility of
superconductivity even though the Fermi velocity of the bands is strictly zero.
However, it is not necessary to resort to this approximation. We demonstrate
that the groundstates and low-energy excitations of a large class of attractive
Hubbard models are exactly solvable, offering a rare, microscopic view of
their physics. The solution reveals the importance of quantum geometry in
escaping (some of) BCS phenomenology within a tractable and nontrivial
strong coupling theory.

This seminar will be held in person and on Zoom:

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