Signatures of the BCS-BEC crossover in the yrast spectra of Fermi quantum rings

Abstract

We study properties of the lowest energy states at non-zero total momentum (yrast states) of the Hubbard model for spin-1/2 fermions in the quantum ring configuration with attractive on-site interaction at low density. In the one-dimensional (1D) case we solve the Hubbard model using the Bethe ansatz, while for the crossover into the 2D regime we use the Full-Configuration-Interaction Quantum Monte-Carlo method (FCIQMC) to obtain the yrast states for the spin-balanced Fermi system. We show how the yrast excitation spectrum changes from the 1D to the 2D regime and how pairing affects the yrast spectra. We also find signatures of fragmented condensation for certain yrast states usually associated with dark solitons.

10 pages, 7 figures

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Cited by in corpus (5)

• Magnetic impurity in a one-dimensional few-fermion system
• Polaron-Depleton Transition in the Yrast Excitations of a One-Dimensional Bose Gas with a Mobile Impurity
• Stochastic differential equation approach to understanding the population control bias in full configuration interaction quantum Monte Carlo
• Odd-frequency superfluidity from a particle-number-conserving perspective
• Two-band atomic superfluidity in the presence of an orbital Feshbach resonance