Abstract
When a parameter quench is performed in an isolated quantum system with a complete set of constants of motion, its out of equilibrium dynamics is considered to be well captured by the Generalized Gibbs Ensemble (GGE), characterized by a set of coefficients related to the constants of motion. We determine the most elementary GGE deviation from the equilibrium distribution that leads to detectable effects. By quenching a suitable local attractive potential in a one-dimensional electron system, the resulting GGE differs from equilibrium by only one single , corresponding to the emergence of an only partially occupied bound state lying below a fully occupied continuum of states. The effect is shown to induce optical gain, i.e., a negative peak in the absorption spectrum, indicating the stimulated emission of radiation, enabling one to identify GGE signatures in fermionic systems through optical measurements. We discuss the implementation in realistic setups.
Highlights
Deviation from Equilibrium: The concept of quantum quench, i.e., the sudden change in the Hamiltonian parameters of an isolated quantum system [1,2,3,4], has an extraordinary impact in both technological applications and fundamental physics
In the case of integrable quantum systems [32], the post-quench dynamics is restricted by a complete set { Îα } of local constants of motions commuting with the post-quench Hamiltonian [33]
In this paper we focus on quadratic Fermi systems and address the following question: what is the most elementary deviation from equilibrium that can produce observable effects? We shall show that quenching a spatially localized potential can lead, under suitable circumstances, to an out of equilibrium state that (i) reaches stationarity and (ii) is described by a Generalized Gibbs Ensemble (GGE) distribution where only one parameter λα deviates from equilibrium, corresponding to an only partially occupied bound state lying below a continuum of fully occupied extended states
Summary
Deviation from Equilibrium: The concept of quantum quench, i.e., the sudden change in the Hamiltonian parameters of an isolated quantum system [1,2,3,4], has an extraordinary impact in both technological applications and fundamental physics. In the case of integrable quantum systems [32], the post-quench dynamics is restricted by a complete set { Îα } of local constants of motions commuting with the post-quench Hamiltonian [33] This implies that, if an out of equilibrium steady state is reached, it can be described by a Generalized Gibbs Ensemble (GGE) density matrix [7,34,35,36,37,38,39,40,41].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
