Revealing Hidden Correlations in a Fermi-Hubbard system via Interaction Ramps

TL;DR

This paper demonstrates how rapid interaction ramps in a cold-atom Fermi-Hubbard system reveal hidden charge-density-wave correlations and distinguish different pairing phases, aiding the study of exotic quantum orders.

Contribution

It introduces a method to enhance and detect nonlocal pairing correlations in the Hubbard model through interaction ramps, enabling new insights into quantum phases.

Findings

Enhanced charge-density-wave correlations after interaction ramps.

Distinguished unpaired Fermi liquid from pseudogap phase.

Technique may observe exotic pair orders and stripe order.

Abstract

We observe an enhanced visibility of charge-density-wave correlations in a cold-atom realization of the attractive Hubbard model following a rapid boost of the interaction strength. The interaction boost associates nonlocal pairs into doublons which mark the center of mass of the original pairs. The enhancement is largest in the strongly correlated regime where pairing is nonlocal. We distinguish the unpaired Fermi liquid from the pseudogap phase of preformed pairs by analyzing atom-resolved spin-charge correlations after the ramp. The technique we establish here may facilitate the observation of exotic forms of pair order in spin-imbalanced systems, and of stripe order in the dual case of the doped repulsive Hubbard model.