Why quantum systems refuse to stay in sync

Coupled oscillators — pendulum clocks, fireflies, power grids — tend to lock in step. Quantum mechanics undermines this: even without classical noise, quantum phase slips tunnel through the energy barrier that holds oscillators synchronized, gradually destroying the lock. Using a path-integral framework, the authors show this effect is distinct from classical decoherence and demonstrate it concretely for superconducting resonators linked by a voltage-biased quantum dot.