报告摘要：Quantum phases at zero temperature can be defined as equivalence classes under local unitary transformations: two ground states are in the same phase if they can be transformed into each other via a local unitary circuit. In this talk, I will discuss how to generalize this circuit-based characterization of phases to systems at finite-temperature described by Gibbs states. We construct a local channel circuit that approximately transforms one Gibbs state into another provided the two are connected by a path in parameter space along which a certain correlation-decay condition holds. As an application, I will show that any system in the same thermal phase as a zero-temperature topological code coherently preserves quantum information for a macroscopically long time, establishing self-correction as a universal property of thermal phases.

个人简介：Dr. Ruochen Ma is a postdoctoral fellow at Kavli Institute for Theoretical Physics, UC Santa Barbara. He obtained his Ph.D. from Perimeter Institute. He is a condensed matter theorist working on topological phases of matter and quantum dynamics.