RESPONSIBILITIES Chair, Department of Physics

APPOINTMENTS Primary appointment in the Physics Department.

INTERESTS Shankar's research focuses on exact solutions in statistical mechanics, effects of random impurities on phase transitions, renormalization group theories of Fermi systems, and the Fractional Quantum Hall Effect.

In statistical mechanics and in the quantum field theory of solids, his graduate student Ganpathy Murthy along with Prof. Shankar worked on random systems in which the interaction between the microscopic degrees of freedom varies from point to point. They worked out several exact solutions. These are particularly useful in systems with competing interactions where intuition is not a very reliable guide, e.g., a random magnet in which each spin receives conflicting signals from its neighbors on which direction to align.

Together with Prof. Subir Sachdev, Physics and Applied Physics, they have worked on the metal-insulator transition and on the properties of holes in quantum antiferromagnets. Recently, he has developed a renormalization group approach to the problem of interacting fermions. The presence of a fermi-surface necessitates a modification of the standard RG procedure which integrates out all high momenta. Using the new approach, he was able to recover the results of Landau's Fermi Liquid Theory, a notoriously mysterious and difficult subject. The new approach makes Fermi Liquid Theory simpler and more straightforward and provides information about its instabilities.

Presently, and sometimes in collaboration with Ganpathy Murthy, I am developing a hamiltonian description of the Fractional Quantum Hall Effect. The description has now reached a point where it allows us to compute gaps for all observed fractions, finite temperature properties like polarization, and the relaxation rate. Our description is also able to map the electronic variables in terms of which the problem is originally posed to the Composite Fermion that are the ultimate quasiparticles. For information on the nature of the problems under research by the Yale theoretical condensed matter physics group, please visit the condensed matter theory group.

CONSULTING AREA Theoretical condensed matter physics, quantum physics.

AWARDS AND HONORS Harwood F. Byrnes/Richard B. Sewall Teaching Prize, Yale University (2005)

REPRESENTATIVE PUBLICATIONS Hamiltonian Description of Composite Fermions: Aftermath, Ramamurti Shankar, 1999, Phys. Rev. Lett., 83, 2382.