Excited-state quantum phase transitions studied from a non-Hermitian perspective

0487461 - FZÚ 2018 RIV US eng J - Článek v odborném periodiku
Šindelka, Milan - Santos, L.F. - Moiseyev, N.
Excited-state quantum phase transitions studied from a non-Hermitian perspective.
Physical Review A. Roč. 95, č. 1 (2017), s. 1-5, č. článku 010103. ISSN 2469-9926. E-ISSN 2469-9934
Grant CEP: GA MŠMT LG15013
Institucionální podpora: RVO:68378271
Klíčová slova: exceptional points * systems * model * signatures * dynamics * freedom * spectra
Obor OECD: Fluids and plasma physics (including surface physics)
Impakt faktor: 2.909, rok: 2017

A main distinguishing feature of non-Hermitian quantum mechanics is the presence of exceptional points (EPs). They correspond to the coalescence of two energy levels and their respective eigenvectors. We show that for finite systems, the exact degeneracies (EPs) obtained with the non-Hermitian LMG Hamiltonian continued into the complex plane are directly linked with the avoided crossings that characterize the ESQPTs for the real (physical) LMG Hamiltonian. The values of the complex control parameter α that lead to the EPs approach the real axis as the system size N →∞. This happens for both the EPs that are close to the separatrix that marks the ESQPT and also for those that are far away, although in the latter case, the convergence rate is smaller.With the method of Pad´e approximants, we can extract the critical value of α.

Trvalý link: http://hdl.handle.net/11104/0282117