[PAST EVENT] Physics Colloquium
There is an old piece of wisdom in condensed matter physics that new materials should always be subjected to measurements at low temperatures. Improvements in high pressure technology have lead an increasing number of researchers to apply this old wisdom to another fundamental thermodynamic variable: pressure. While lowering the temperature reveals the underlying quantum ground state, applying high pressure often induces the emergence of entirely new ground states. In this talk I will provide an overview of experiments that we have performed using pressures that span the range from kilobars (the pressure at the bottom of the ocean) to megabars (the pressure at the core of the earth). In particular, I will outline experiments aimed at understanding a new type of quantum phase transition, i.e., the transition between topologically trivial and non-trivial states of matter. In addition, I will discuss the results of work we have performed that is motivated by two recent milestones in the history of high pressure science: The discovery of pressure induced superconductivity above 200 K in hydrogen sulfide and the metallization of hydrogen.