Two Fermions in a double well: Exploring a fundamental building block of the Hubbard model

TL;DR

This study demonstrates precise control over two ultracold fermionic atoms in a double-well potential, enabling exploration of fundamental quantum states relevant to the Hubbard model and quantum simulation.

Contribution

It provides the first experimental realization of a controllable two-fermion system in a double well, simulating key states of the Fermi-Hubbard model.

Findings

Realized a two-particle analog of a Mott-insulating state.

Observed effects of second-order tunneling on energy levels.

Achieved independent control of interaction, tunneling, and tilt.

Abstract

We have prepared two ultracold fermionic atoms in an isolated double-well potential and obtained full control over the quantum state of this system. In particular, we can independently control the interaction strength between the particles, their tunneling rate between the wells and the tilt of the potential. By introducing repulsive (attractive) interparticle interactions we have realized the two-particle analog of a Mott-insulating (charge-density-wave) state. We have also spectroscopically observed how second-order tunneling affects the energy of the system. This work realizes the first step of a bottom-up approach to deterministically create a single-site addressable realization of a ground-state Fermi-Hubbard system.