Magnetoexcitons Break Antiunitary Symmetries.

We show analytically and numerically that the application of an external magnetic field to highly excited Rydberg excitons breaks all antiunitary symmetries in the system. Only by considering the complete valence band structure of a direct-band-gap cubic semiconductor, the Hamiltonian of excitons leads to the statistics of a Gaussian unitary ensemble without the need for interactions with other quasiparticles like phonons. Hence, we give theoretical evidence for a spatially homogeneous system breaking all antiunitary symmetries.