Eighty-five years after the formulation of Schrodinger's equation, computational quantum mechanics is a very successful field. A myriad of approximations exist that at reasonably low computational cost can get the “right answer for the right reason” for most molecules and materials. However, there is a dark secret to this success story: these methods break down for the strongly correlated electrons found in high-temperature superconducting materials. Higher temperatuer superconductors are central to the development of disruptive technologies for transmitting electricity without heat losses. A predictive quantum model is still lacking and is in fact deemed impossible by many. Dr. Gustavo Scuseria and Dr. Randy Hulet, of Rice University, are developing methods for computing and experimentally simulating solutions to the correlation problem as expressed in the Hubbard model--the primary model used to explain superconductivity. The convergence of radically new theoretical and experimental approaches presents a unique opportunity for advancing our understanding of strongly correlated matter.

In a recent breakthrough, Scuseria has proven that a simplified version of the very successful coupled cluster method of quantum chemistry can accurately model the near degeneracies and long-range character of strong correlation. This new theory paired with Dr. Scuseria’s demonstration of an accurate and affordable description of extended systems has offered new and encouraging results. Meanwhile, Dr. Hulet has developed a new scheme to cool atoms to temperatures of a few nano-Kelvin on an “optical lattice” made from laser beams. Hulet uses atoms confined to an optical lattice to simulate the behavior of electrons in the crystal lattice of a superconducting material. Dr. Hulet’s experiments will add a synergistic feedback loop to Dr. Suseria’s theory, to validate their accuary. This promising convergence is exceptional and had remained unrealizable until the two groups devised these unique methodologies.

Current research includes:

• Understanding Materials: Superconductors revolutionized physics and have the potential to revolutionize technology. If researchers could devise a superconductor that operated at room temperature, they could transport electricity without any loss. After thirty years of intense effort however, researchers still do not know how high temperature superconductors work. Dr. Scuseria and Dr. Hulet are working to understand superconductors better to try to use that understanding to devise novel materials with exceptional properties.

• Solving the Hubbard Problem: Dr. Scuseria uses special theoretical tools that he is applying to the Hubbard model which is the primary model to explain superconductivity. Using experimental techniques, Dr. Hulet is simulating the Hubbard model and instead of a digital computer, using the lithium atoms contained in the lattice as an analog quantum computer to solve the problem.