# Bottom-up configuration-interaction emulations of ultracold fermions in entangled optical plaquettes: building blocks of unconventional superconductivity

## TL;DR

This paper introduces a configuration-interaction method for emulating unconventional superconductivity using ultracold fermions in optical traps, analyzing entanglement, symmetry-breaking, and coupling effects in plaquette systems.

## Contribution

The paper presents a novel microscopic CI methodology for simulating superconductivity phenomena in ultracold atoms, connecting to Hubbard models and exploring multi-plaquette interactions.

## Key findings

- Single-occupancy RVB states only partially explain many-body solutions.
- CI results map onto a Hubbard Hamiltonian, not a t-J model.
- Symmetry-breaking and coupling effects significantly influence spectral properties.

## Abstract

A microscopic configuration-interaction (CI) methodology is introduced to enable bottom-up Schroedinger-equation emulation of unconventional superconductivity in ultracold optical traps. We illustrate the method by exploring the properties of Lithium-6 atoms in a single square plaquette in the hole-pairing regime, and by analyzing the entanglement (symmetry-preserving) and disentanglement physics (via symmetry-breaking, associated with the separation of charge and spin density waves) of two coupled plaquettes in the same regime. The single-occupancy RVB states contribute only partially to the exact many-body solutions, and the CI results map onto a Hubbard Hamiltonian, but not onto the double-occupancy-excluding t-J one. For the double-plaquette case, effects brought about by breaking the symmetry between two weakly-interacting plaquettes, either by distorting, or by tilting and detuning, one of the plaquettes with respect to the other, as well as spectral changes caused by increased coupling between the two plaquettes, are explored.