Scientists at ETH Zurich use cold atoms to simulate graphene

Scientists at ETH Zurich used a set of laser beams to create a honeycomb-like structure similar to that found in graphene. By loading ultracold atoms into this optical lattice, they can simulate electronic properties of this promising material. Such experiments may be used to identify electronic properties of materials which have yet to be discovered. Tilman Esslinger and his team loaded ultracold potassium atoms into a special lattice structure made of laser light: the researchers used a set of orthogonal and precisely positioned laser beams to create a variety of two-dimensional light field geometries, including the honeycomb structure of graphene. In the experiment they cooled several hundred thousand potassium atoms inside a vacuum chamber to temperatures just above absolute zero, thereby bringing the atoms to rest. Then, they place the optical lattice over the cloud of atoms. A great challenge was to precisely control the laser beams. “Designing a structure like this with laser beams is similar to creating a beautifully regular pattern in a lake by simultaneously throwing several pebbles in at carefully chosen positions”, says Esslinger.