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Physical Review A

Route toward classical frustration and band flattening via optical lattice distortion

Pil Maria Saugmann, José Vargas, Yann Kiefer, Max Hachman, R. Eichberger, Andreas Hemmerich, Jonas Larson

Published Oct 27, 2022• 3 citations
Publisher

Abstract

The authors suggest a method to emulate classically frustrated models in systems of ultracold atoms loaded in an optical lattice. The proposal is studied both experimentally and with numerical simulations.
DOI
10.1103/physreva.106.l041302

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Orbital degrees of freedom play an important role in understanding the emergence of unconventional quantum phases. Ultracold atomic gases in optical lattices provide a wonderful platform to simulate orbital physics. In this work, we consider spinless fermionic atoms loaded into ppp-orbital bands of a two-dimensional frustrated triangular lattice. The system can be described by an extended Fermi-Hubbard model, which is numerically solved by using the orbital version of real-space dynamical mean-field theory. Due to the interplay of anisotropic hoppings and geometrical frustration, a rich phase diagram is found, including stripe-orbital, paraorbital, and ferro-orbital phases, in contrast to its bosonic analog with orbital-skyrmion ordering in the identical lattice. In order to understand the underlying mechanics of competing orbital orders, we derive an effective orbital-exchange model, which yields consistent explanation with our main numerical results.