Quantum Simulation of Semiconductor Excitons in Ultracold Dipolar Fermi Gases

Abstract

Inspired by the progress on the study of exciton physics in atomically thin transition metal dichalcogenide (TMD) semiconductors, we investigate the formation of analogs of excitons in cold atomic systems. To this end, we consider single-component fermions comprised of ultracold ground-state molecules or dipolar atoms in a hexagonal optical lattice. An energy offset between triangular sublattices opens up a band gap with degeneracies at the K/K' points as in TMDs. We predict the existence of cold atomic excitons and show that cold atoms allow us to study excitons from the weak-coupling regime, where effective mass models apply, to the strong-interaction regime, described by flat-band models. We demonstrate how these excitons can be observed using lattice modulation spectroscopy, and how their wave functions can be mapped out using quantum gas microscopy. Firmly establishing the idea of quantum simulation of semiconductor physics, this work lays the foundation for simulating complex electronic states such as trions, polarons and excitonic insulators.