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

oleh: Ulrich Ebling, Ali Alavi, Joachim Brand

Format: Article
Diterbitkan: American Physical Society 2021-05-01

Deskripsi

We study properties of the lowest energy states at nonzero 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 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.