Dr. Lee Liu, JILA and Department of Physics, University of Colorado

"Ergodicity breaking in C60 fullerenes"

Abstract: Statistical mechanics is founded on the assumption of ergodicity. For example, gas diffuses to fill a room, and heat spreads throughout an iron workpiece. Discovering new mechanisms for breaking ergodicity is of great interest for engineering useful materials and probing matter out of equilibrium.

In fact, everyday life is full of systems that break ergodicity, but they often do so by breaking a fundamental symmetry. Familiar examples include magnets, superconductors, and the universe itself. Our work arises from the question: can we break ergodicity without breaking symmetry?

I will describe how a simple molecule, buckminsterfullerene (C60) breaks ergodicity while preserving its fundamental symmetry. Surprisingly, we also found that ergodicity is broken and restored again as the molecule spins faster and faster [1]. These insights may be relevant to protecting quantum coherence in complex systems, engineering useful quantum materials, and probing matter out of equilibrium, inspired by the dynamics of rotating molecules.

1. Lee R. Liu, Dina Rosenberg, P. Bryan Changala, Philip J. D. Crowley, David J. Nesbitt, Norman Y. Yao, Timur V. Tscherbul, and Jun Ye. Science 381, 778-783 (2023)