Optimized Confinement of Fermions in Two Dimensions

TL;DR

This paper compares different confinement methods for fermions in two-dimensional optical lattices using Quantum Monte Carlo, highlighting the strengths of each method for observing magnetic and superconducting phenomena.

Contribution

It introduces and evaluates off-diagonal confinement as a new method and compares it with traditional and uniform density traps for fermions in 2D optical lattices.

Findings

Conventional diagonal confinement yields the strongest magnetic signals.

Constant density traps provide more robust signals for d-wave pairing.

Off-diagonal confinement can achieve uniform density profiles.

Abstract

One of the challenging features of studying model Hamiltonians with cold atoms in optical lattices is the presence of spatial inhomogeneities induced by the confining potential, which results in the coexistence of different phases. This paper presents Quantum Monte Carlo results comparing meth- ods for confining fermions in two dimensions, including conventional diagonal confinement (DC), a recently proposed 'off-diagonal confinement' (ODC), as well as a trap which produces uniform den- sity in the lattice. At constant entropy and for currently accessible temperatures, we show that the current DC method results in the strongest magnetic signature, primarily because of its judicious use of entropy sinks at the lattice edge. For d-wave pairing, we show that a constant density trap has the more robust signal and that ODC can implement a constant density profile. This feature is important to any prospective search for superconductivity in optical lattices.