Simulation and detection of Weyl fermions in ultracold Fermi gases with Raman-assisted spin-orbit coupling

TL;DR

This paper explores the theoretical possibility of realizing Weyl fermions in ultracold Fermi gases with Raman-assisted spin-orbit coupling, analyzing their properties, topological features, and experimental detection methods.

Contribution

It extends previous schemes to fermionic systems, detailing Weyl point dynamics, topological invariants, and proposing experimental verification in ultracold Fermi gases.

Findings

Weyl points can be manipulated by tuning the Zeeman field.

Topological properties are characterized by Chern numbers.

Experimental detection via density profile measurements is feasible.

Abstract

Weyl fermion, also referred to as pseudo-magnetic monopole in momentum space, is an undiscovered massless elementary particle with half-integer spin predicted according to relativistic quantum field theory. Motivated by the recent experimental observation of Weyl semimetal band in ultracold Bose gases with Raman-assisted 3D spin-orbit coupling, we investigate the properties and possible observation of Weyl fermions in the low-energy quasi-particle excitations of ultracold Fermi gases. Following a previous suggestion that the existing Raman lattice scheme can be readily generalized to fermionic systems, here we discuss the movement of the Weyl points in the Brillouin Zone, as well as the creation and annihilation of Weyl fermions by adjusting the effective Zeeman field. The relevant topological properties are also demonstrated by calculating the Chern number. Furthermore, we propose how to experimentally verify the existence of the Weyl fermions and the associated quantum phase transition via density profile measurements.