Equilibration and GGE in interacting-to-free Quantum Quenches in dimensions d>1

摘要: Ground states of interacting QFTs are non-gaussian states, i.e. their connected n-point correlation functions do not vanish for n>2, in contrast to the free QFT case. We show that when ground state an evolves under a massive long time (a scenario can be realised by Quantum Quench), decay and all local physical observables equilibrate values given gaussian density matrix keeps memory only two-point initial function. The argument hinges upon fundamental principle cluster decomposition, which is valid general QFT. An analogous result was already known case d=1 spatial dimensions, where it special so-called Generalised Gibbs Ensemble (GGE) hypothesis, we now generalise higher dimensions. Moreover massless evolution, despite fact evolution may lead equilibration but unbounded increase correlations with instead, GGE gives correctly leading order asymptotic behaviour thermodynamic large limit. demonstration performed context bosonic relativistic QFT, arguments apply more generally.