Creating State-Dependent Lattices for Ultracold Fermions by Magnetic Gradient Modulation

TL;DR

This paper introduces a method to create state-dependent optical lattices for ultracold fermions using magnetic gradient modulation, enabling control over tunneling and localization based on spin states.

Contribution

The study presents a novel technique for tuning tunneling amplitudes and signs in optical lattices via magnetic gradient modulation, allowing for spin-dependent control of fermionic atoms.

Findings

Different momentum distributions observed for various spin states.

Good agreement between experimental results and theoretical band structure predictions.

Achieved localization of one spin state while others remained mobile.

Abstract

We demonstrate a versatile method to create state-dependent optical lattices by applying a magnetic field gradient modulated in time. This allows for tuning the relative amplitude and sign of the tunnelling for different internal states. We observe substantially different momentum distributions depending on the spin-state of fermionic 40K atoms. Using dipole-oscillations we probe the spin-dependent band structure and find good agreement with theory. In-situ expansion-dynamics demonstrate that one state can be completely localized whilst others remain itinerant. A systematic study shows negligible heating and lifetimes of several seconds in the Hubbard regime.