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Résumé |
Past decades have revealed the crucial role played by the entanglement structure
of quantum states in explaining both phases of matter and thermalization—the
emergence of statistical physics from unitary time evolution. Yet our
understanding of entanglement in relativistic field theories remains limited,
largely confined to conformal and holographic settings.
At the same time, we don't have a clear picture of how our universe actually
reached thermal equilibrium after inflation. We do not understand why the quark-
gluon plasma produced in heavy-ion collisions thermalizes so fast, or what the
actual phase diagram of QCD is.
In this talk, I illustrate how progress can be made in filling this gap starting
from the study of one-dimensional relativistic field theories. I present results
on the real-time dynamics of the massive Schwinger model, which shares key
features with QCD. In this setup, the medium created by hard back-to-back
particles thermalizes through entanglement production. I then move on to discuss
how a refined understanding of entanglement in relation to symmetries can serve as
a practical tool for detecting and characterizing different phases of matter.
Indeed, the so-called "entanglement asymmetry" related to the chiral symmetry in
the Schwinger model can be computed analytically in the massless limit, as a
function of temperature. Remarkably, it is parametrically more sensitive to
symmetry breaking than the corresponding local order parameter, the chiral
condensate.
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