Temperature Correlations of Quantum Spins
  We consider isotropic XY model in the transverse magnetic field on the one dimensional lattice. Another name of the model in Heisenberg XXO model of spin 1/2.We solved long standing problem of evaluation of temperature correlations. We first represent correlation function in the model, by means of completely integrable differential equation. This is famous Ablowitz-Ladik lattice Nonlinear Schrodinger equation.Correlation function is the $\tau $ function of this differential equation. We solved this equation and evaluate asymptotics. 
Alexandr Its, Anatloij Izergin, Vladimr Korepin, Nikita Slavnov