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Measuring effective temperatures in a generalized Gibbs ensemble

April 24, 2017 - 11:00am
Leticia Cugliandolo
Université Pierre et Marie Curie

Quantum integrable models display a rich landscape of non-thermal excited
states with exotic properties. The most common way to probe them is by
performing a quantum quench, namely, by letting a many-body initial state
unitarily evolve with an integrable Hamiltonian. At late times, these
systems are  locally described by a Generalized Gibbs Ensemble with as
many effective temperatures, storing a memory of the initial state, as
conserved quantities. The direct measurement of the macroscopic number of
effective temperatures remains elusive. We show that they can be obtained
from the measurement of dynamical correlations in the asymptotic limit
after the quench if one employs a generalized fluctuation-dissipation
theorem that we provide. Our procedure allows to completely reconstruct
the stationary state of a quantum integrable system from state-of-art
experimental observations.

        •       Measuring effective temperatures in a generalized Gibbs ensemble
       Laura Foini, Andrea Gambassi, Robert Konik and Leticia F. Cugliandolo

        •       Probing non-thermal density fluctuations in the one-dimensional Bose gas
       Jacopo de Nardis, Milosz Panfil, Laura Foini, Andrea Gambassi,
Leticia F. Cugliandolo, and Robert Konik

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