Nonthermal Fixed Points in Quantum Field Theory Beyond the Weak-Coupling Limit

Understand

Quantum systems in extreme conditions can exhibit universal behavior far from equilibrium associated to nonthermal fixed points with a wide range of topical applications from early-universe inflaton dynamics and heavy-ion collisions to strong quenches in ultracold quantum gases.

• So far, most studies have relied on a mapping of the quantum dynamics onto a classical-statistical theory that can be simulated on a computer.
• However, the mapping is based on a weak-coupling limit, while phenomenological applications often require moderate interaction strengths.
• We report on the observation of nonthermal fixed points directly in quantum field theory beyond the weak-coupling limit.