Negative compressibility, in which a system lowers its energy with increasing density, is an unusual feature of strongly-correlated systems with long-ranged Coulomb interactions. In this talk I first show how negative compressibility arises in two-dimensional electron gases, including conventional semiconductor heterostructures and graphene, and discuss its experimental signature. I then show how similar physics is behind the remarkable performance of supercapacitors, which are energy storage devices capable of storing hundreds of Coulombs of electric charge within a single cubic centimeter of volume. Finally, I discuss how an understanding of correlation-enhanced compressibility enabled us to resolve a long-standing puzzle associated with the behavior of human crowds.
Cm-Bio 4-02 Skinner