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Title: Do dynamical transitions occur only for quenches across critical points
Plain: Kinks in the return probability were first found for sudden changes that cross an ordinary phase transition. Some models show kinks without such a crossing, and others show a crossing without kinks, and the rule that decides which happens is missing.
Precise: For a quench $H_i \to H_f$ with Loschmidt rate $l(t) = -\operatorname{lim}_{N \to \infty} (1/N) \operatorname{ln} \mid\langle\psi_0\mid \operatorname{exp}(-i H_f t/\hbar) \mid\psi_0\rangle\mid^2$, determine the conditions on $(H_i, H_f)$ under which nonanalytic times $t_c$ exist if and only if the quench crosses an equilibrium critical point. Known counterexamples from 2014 on violate both directions in specific models. Answer: a criterion valid for interacting nonintegrable models.
Settled by: A criterion proved, or verified numerically across interacting nonintegrable models in $d = 1\text{ and }2$.
Kind: well-posed
Answer type: classification
References: (empty)
Literature status: open
Status note: (empty)
Posed since: (empty)