title: Lee-Yang zeros and critical times in decoherence of a probe spin coupled to a bath.
abstract: Phase transitions are not usually seen in the time domain. Here, we report on the finding of critical times at which a physical observable, in the thermodynamic limit, becomes nonanalytic as a function of time. We find that the coherence of a probe spin coupled to a many-body system vanishes at times in one-to-one correspondence to the Lee-Yang zeros of the partition function of the many-body system. In the thermodynamic limit, the Lee-Yang zeros form a continuum cut in the complex plane of fugacity and the probe spin coherence presents sudden death and birth at the critical times corresponding to the Yang-Lee singularities. These results provide new experimental possibilities in many-body physics.
authors.affiliation: Department of Physics, The Chinese University of Hong Kong, Hong Kong, China.
authors.forename: Bo-Bo
authors.initials: BB
authors.lastname: Wei
authors.forename: Ren-Bao
authors.initials: RB
authors.lastname: Liu