Quantum Breaking of Elastic String
  Breaking of an atomic chain under stress is a collective many-particle tunneling phenomenon. We study classical dynamics in imaginary time by using conformal mapping technique, and derive an analytic formula for the probability of breaking. The result covers a broad temperature interval and interpolates between two regimes: tunneling and thermal activation. Also, we consider the breaking induced by an ultrasonic wave propagating in the chain, and propose to observe it in an STM experiment. 
L. S. Levitov, A. V. Shytov, and A. Yu. Yakovets