We consider the one-parameter families of transfer operators for geodesic flows on negatively curved manifolds. We show that the spectra of the generators have some “band structure” parallel to the imaginary axis. As a special case of “semi-classical” transfer operator, we see that the eigenvalues concentrate around the imaginary axis with some gap on the both sides.

This video was produced by CIRM as part of the conference Hyperbolicity and dimension.