João Costa, Pedro Ribeiro, Andrea De Luca, Tomaž Prosen, Lucas Sá
SciPost Phys. 15, 145 (2023) ·
published 9 October 2023

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We study spectral and steadystate properties of generic Markovian dissipative systems described by quadratic fermionic Liouvillian operators of the Lindblad form. The Hamiltonian dynamics is modeled by a generic random quadratic operator, i.e., as a featureless superconductor of class D, whereas the Markovian dissipation is described by $M$ random linear jump operators. By varying the dissipation strength and the ratio of dissipative channels per fermion, $m=M/(2N_F)$, we find two distinct phases where the support of the singleparticle spectrum has one or two connected components. In the strongly dissipative regime, this transition occurs for $m=1/2$ and is concomitant with a qualitative change in both the steadystate and the spectral gap that rules the largetime dynamics. Above this threshold, the spectral gap and the steadystate purity qualitatively agree with the fully generic (i.e., nonquadratic) case studied recently. Below $m=1/2$, the spectral gap closes in the thermodynamic limit and the steadystate decouples into an ergodic and a nonergodic sector yielding a nonmonotonic steadystate purity as a function of the dissipation strength. Our results show that some of the universal features previously observed for fully random Liouvillians are generic for a sufficiently large number of jump operators. On the other hand, if the number of dissipation channels is decreased the system can exhibit nonergodic features, rendering it possible to suppress dissipation in protected subspaces even in the presence of strong systemenvironment coupling.
Giuseppe Del Vecchio Del Vecchio, Andrea De Luca, Alvise Bastianello
SciPost Phys. 12, 060 (2022) ·
published 14 February 2022

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We consider 1D integrable systems supporting ballistic propagation of excitations, perturbed by a localised defect that breaks most conservation laws and induces chaotic dynamics. Focusing on classical systems, we study an outofequilibrium protocol engineered activating the defect in an initially homogeneous and far from the equilibrium state. We find that large enough defects induce full thermalisation at their center, but nonetheless the outgoing flow of carriers emerging from the defect is nonthermal due to a generalization of the celebrated Boundary Thermal Resistance effect, occurring at the edges of the chaotic region. Our results are obtained combining abinitio numerical simulations for relatively smallsized defects, with the solution of the Boltzmann equation, which becomes exact in the scaling limit of large, but weak defects.
Giuseppe Del Vecchio Del Vecchio, Alvise Bastianello, Andrea De Luca, Giuseppe Mussardo
SciPost Phys. 9, 002 (2020) ·
published 6 July 2020

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We study the outofequilibrium properties of a classical integrable nonrelativistic theory, with a time evolution initially prepared with a finite energy density in the thermodynamic limit. The theory considered here is the NonLinear Schrodinger equation which describes the dynamics of the onedimensional interacting Bose gas in the regime of high occupation numbers. The main emphasis is on the determination of the latetime Generalised Gibbs Ensemble (GGE), which can be efficiently seminumerically computed on arbitrary initial states, completely solving the famous quench problem in the classical regime. We take advantage of known results in the quantum model and the semiclassical limit to achieve new exact results for the momenta of the density operator on arbitrary GGEs, which we successfully compare with abinitio numerical simulations. Furthermore, we determine the whole probability distribution of the density operator (full counting statistics), whose exact expression is still out of reach in the quantum model.
SciPost Phys. 7, 024 (2019) ·
published 23 August 2019

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We study the entanglement entropy of the quantum trajectories of a free fermion chain under continuous monitoring of local occupation numbers. We propose a simple theory for entanglement entropy evolution from disentangled and highly excited initial states. It is based on generalized hydrodynamics and the quasiparticle pair approach to entanglement in integrable systems. We test several quantitative predictions of the theory against extensive numerics and find good agreement. In particular, the volume law entanglement is destroyed by the presence of arbitrarily weak measurement.
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