I was excited to hear that Charlie Kane, Laurens Molenkamp and Shoucheng Zhang were among the recipients of the 2013 Physics Frontiers Prize. Their seminal works both theoretically predicting and experimentally discovering the topological insulator have profoundly influenced the direction of condensed matter physics over the past few years and have shaped my own research agenda at Caltech.

I first learned about the topological insulator from a talk Charlie Kane delivered at the 2006 American Physical Society March Meeting. It was around this time that graphene was exploding onto the scene following Andre Geim and Konstantin Novoselov’s demonstration that single sheets of it could be peeled from graphite using Scotch tape. Inspired by the highly unconventional charge transport properties that were being measured from graphene, Charlie had begun to think about whether its spin transport properties might also yield surprises. The huge surprise, as Charlie would reveal in his talk, was that graphene could theoretically exhibit a quantum spin Hall effect in which spin-polarized charge carriers flow without dissipation along the edges of an electrically insulating material. Such quantum spin Hall insulators (later renamed the 2D topological insulator), as Charlie and his colleague Eugene Mele proved, are a phase of matter distinct from ordinary electrical insulators by virtue of a quantum entanglement of its electrons.
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