Physical Society Colloquium

New topological quantum states in condensed matter physics

William Halperin

Department of Physics & Astronomy
Northwestern University

The new states to which I refer in the title have recently been studied in my laboratory and are thought to exist in a number of superconducting compounds, like UPt₃, Sr₂RuO₄, and superfluid ³He.

In the past few years or more, the condensed matter physics community has become enamored of manifestations of long range coherence in these superconductors and superfluids, driven in part from predictions for their potential application to quantum computation. This is an interesting subject in its own right. However, I will focus my story on the relevant physical property, chiral symmetry, most clearly in evidence in UPt₃ and superfluid ³He. These systems have multiple thermodynamic phases, each with a different order parameter structure. After introducing the subject I will give a tour of search and discovery at ultra-low temperatures.