Spectral Analysis for Gaussian Quantum Markov Semigroups

We investigate the spectrum of the generator induced on the space of Hilbert-Schmidt operators by a Gaussian quantum Markov semigroup with a faithful normal invariant state in the general case, without any symmetry or quantum detailed balance assumptions. We prove that the eigenvalues are entirely determined by those of the drift matrix, similarly to classical Ornstein-Uhlenbeck semigroups. This result is established using a quasi-derivation property of the generator. Moreover, the same spectral property holds for the adjoint of the induced generator. Finally, we show that these eigenvalues constitute the entire spectrum when the induced generator has a spectral gap.