An ultracold graphene analog
Two highly active fields of physics have merged in recent years, as researchers work to build models of condensed matter systems using ultracold atoms suspended in optical lattices. Graphene provides an environment for many intriguing physics problems, with its massless fermions, unusually high carrier mobility, and anomalous quantum Hall behavior. Now, Kean Loon Lee and colleagues at the National University of Singapore, and at Ecole Normale Supérieure and Institut Non Linéaire de Nice in France, report in Physical Review A their theoretical studies of ultracold atoms arranged in a hexagonal graphenelike optical lattice.
When atoms are loaded into optical traps researchers can control their position and the strength of their interactions. The authors model a two-dimensional honeycomb lattice of traps created by the interference of three laser beams. They then carry out tight-binding calculations of the band structure to show that a signature of graphene—transport of massless excitations—could indeed exist in this analogous system. Lee et al. also study the hopping of nearest-neighbor atoms and the influence of lattice distortions, providing a useful guidepost to future experimental efforts. – David Voss