Experimental realization of strong effective magnetic fields in optical superlattice potentials

TL;DR

This paper demonstrates the experimental creation of large, tunable effective magnetic fields for ultracold atoms in optical superlattices using photon-assisted tunneling, enabling studies of quantum phenomena like frustration and cyclotron orbits.

Contribution

The work introduces a general, atom-structure-independent method to generate artificial gauge fields with large flux per plaquette in optical lattices.

Findings

Realization of large effective magnetic flux in optical superlattices.

Observation of degenerate ground states due to magnetic frustration.

Direct visualization of quantum cyclotron orbits.

Abstract

We present the experimental generation of large effective magnetic fields for ultracold atoms using photon-assisted tunneling in an optical superlattice. The underlying method does not rely on the internal structure of the atoms and therefore constitutes a general approach to realize widely tunable artificial gauge fields without the drawbacks of near-resonant optical potentials. When hopping in the lattice, the accumulated phase shift by an atom is equivalent to the Aharonov-Bohm phase of a charged particle exposed to a staggered magnetic field of large magnitude, on the order of one flux quantum per plaquette. We study the ground state of this system and observe that the frustration induced by the magnetic field can lead to a degenerate ground state for non-interacting particles. We provide a local measurement of the phase acquired by single particles due to photon-assisted tunneling. Furthermore, the quantum cyclotron orbit of single atoms in the lattice exposed to the effective magnetic field is directly revealed.