Prof. A.  Schofield

Quantum criticality

Abstract


One of the most important developments over the last ten years in condensed matter physics has been the study of quantum phase
transitions and associated quantum criticality. In contrast to a thermal phase transition where thermal fluctuations mediate the
transition, it is quantum fluctuations which drive a quantum phase transition at zero temperature. Surprisingly, experiments are showing how a quantum critical point at zero temperature can influence a wide region of the phase diagram at finite temperature. These same
experiments are also pushing the existing theoretical framework of phase transitions to breaking point. Quantum critical points are currently being postulated as the answer to mysteries as diverse as high temperature superconductivity and the space-time singularity at a
black hole. In this talk I will review the notion of quantum criticality and the puzzles we are facing in trying to understand
matter pushed to its extremes at a quantum critical point.