title: Quantum chaos and breaking of all anti-unitary symmetries in Rydberg excitons.
abstract: Symmetries are the underlying principles of fundamental interactions in nature. Chaos in a quantum system may emerge from breaking these symmetries. Compared to vacuum, crystals are attractive for studying quantum chaos, as they not only break spatial isotropy, but also lead to novel quasiparticles with modified interactions. Here we study yellow Rydberg excitons in cuprous oxide which couple strongly to the vacuum light field and interact significantly with crystal phonons, leading to inversion symmetry breaking. In a magnetic field, time-reversal symmetry is also broken and the exciton states show a complex splitting pattern, resulting in quadratic level repulsion for small splittings. In contrast to atomic chaotic systems in a magnetic field, which show only a linear level repulsion, this is a signature of a system where all anti-unitary symmetries are broken simultaneously. This behaviour can otherwise be found only for the electro-weak interaction or engineered billiards.
authors.affiliation: Experimentelle Physik 2, Technische Universität Dortmund, 44221 Dortmund, Germany.
authors.forename: Marc
authors.identifier: 0000-0003-4953-1286
authors.initials: M
authors.lastname: Aßmann
authors.affiliation: Experimentelle Physik 2, Technische Universität Dortmund, 44221 Dortmund, Germany.
authors.forename: Johannes
authors.initials: J
authors.lastname: Thewes
authors.affiliation: Experimentelle Physik 2, Technische Universität Dortmund, 44221 Dortmund, Germany.
authors.forename: Dietmar
authors.initials: D
authors.lastname: Fröhlich
authors.affiliation: Experimentelle Physik 2, Technische Universität Dortmund, 44221 Dortmund, Germany.|Ioffe Institute, Russian Academy of Sciences, 194021 St Petersburg, Russia.
authors.forename: Manfred
authors.initials: M
authors.lastname: Bayer
mesh_terms: D003198:Computer Simulation; D003300:Copper / Q000737:chemistry* / Q000528:radiation effects*; D004583:Electrons; D004735:Energy Transfer; D060526:Magnetic Fields; D008956:Models, Chemical; D017711:Nonlinear Dynamics; D011789:Quantum Theory; D011829:Radiation Dosage; D055672:Static Electricity
chemical_list: D003300:Copper; C030973:cupric oxide