Ground-state fidelity in the BCS-BEC crossover

TL;DR

This paper explores the use of ground-state fidelity susceptibility to analyze the BCS-BEC crossover in fermionic systems, demonstrating its potential as a tool for understanding crossover phenomena across different models.

Contribution

It applies the concept of ground-state fidelity susceptibility to the BCS-BEC crossover, showing its usefulness beyond quantum phase transitions.

Findings

Fidelity susceptibility varies across the crossover.

Applicable to contact and finite-range potentials.

Works for both continuum and lattice models.

Abstract

The ground-state fidelity has been introduced recently as a tool to investigate quantum phase transitions. Here, we apply this concept in the context of a crossover problem. Specifically, we calculate the fidelity susceptibility for the BCS ground-state wave function, when the intensity of the fermionic attraction is varied from weak to strong in an interacting Fermi system, through the BCS-BEC crossover. Results are presented for contact and finite-range attractive potentials and for both continuum and lattice models. We conclude that the fidelity susceptibility can be useful also in the context of crossover problems.