0531626 - ÚJF 2021 RIV NL eng J - Journal Article
Znojil, Miloslav - Borisov, D. I.
Anomalous mechanisms of the loss of observability in non-Hermitian quantum models.
Nuclear Physics. B. Roč. 957, č. 8 (2020), č. článku 115064. ISSN 0550-3213. E-ISSN 1873-1562
Institutional support: RVO:61389005
Keywords : time symmetry * spectral singularities * optical lattices
OECD category: Particles and field physics
Impact factor: 2.759, year: 2020
Method of publishing: Open access
https://doi.org/10.1016/j.nuclphysb.2020.115064

Via several toy-model quantum Hamiltonians H (lambda) of a non-tridiagonal low-dimensional matrix form the existence of unusual observability horizons is revealed. At the corresponding limiting values of parameter lambda = lambda((critical)) these new types of quantum phase transitions are interpreted as the points of confluence of several decoupled Kato's exceptional points of equal or different orders. Such a phenomenon of degeneracy of non-Hermitian degeneracies seems to ask for a reclassification of the possible topologies of the complex energy Riemann surfaces in the vicinity of branch points.
Permanent Link: http://hdl.handle.net/11104/0310251