Multi-Component Fermi Gases in a Honeycomb Lattice

This research program will use ultracold atoms to emulate, with precise experimental control, the behavior of electrons in graphene, a technologically interesting allotrope of carbon, and that of fundamental particles (e.g. quarks or leptons) governed by the laws of special relativity and quantum mechanics. In doing so, this program can elucidate open questions regarding the equilibrium and dynamical behaviors of such systems when comprised of many particles that strongly interact. To achieve this, ultracold lithium-6 atoms will be confined in an optical lattice potential formed from interfering laser fields which produce a honeycomb intensity pattern through which the atoms move. This lattice potential mimics that experienced by electrons in graphene which move through a honeycomb lattice of carbon ions. At a particular filling fraction of the lattice sites, the low-energy excitations of the system are governed by the laws of relativistic quantum mechanics but with an effective speed of light that is orders of magnitude smaller, making the direct observation of relativistic quantum dynamics experimentally feasible. Phenomena to be studied include Klein tunneling, Veselago lensing, chiral symmetry breaking, and the effect of interactions and disorder on particle mobility. These phenomena are relevant both for understanding electron transport in graphene and elucidating fundamental predictions of relativistic quantum mechanics.

The investigations of transport (including the role that interactions and disorder play) and mechanisms for opening a bandgap in a two-dimensional honeycomb lattice can potentially aid the development of nanoelectronic devices based on graphene such as ultra-high speed transistors and novel electron optics devices. The opening of a bandgap due to interactions will also provide insight into chiral symmetry breaking and mass generation in quantum chromo-dynamics. In carrying out this research, undergraduate students, graduate students, and postdoctoral researcher associates will be trained in the use of modern technology, analytical thinking, scientific writing and giving clear oral presentations. This research program will continue to recruit students from demographic groups underrepresented in the sciences.