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

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61389021%3A_____%2F17%3A00494834" target="_blank" >RIV/61389021:_____/17:00494834 - isvavai.cz</a>

Nalezeny alternativní kódy

RIV/68378271:_____/17:00487461

Výsledek na webu

<a href="https://link.aps.org/accepted/10.1103/PhysRevA.95.010103" target="_blank" >https://link.aps.org/accepted/10.1103/PhysRevA.95.010103</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1103/PhysRevA.95.010103" target="_blank" >10.1103/PhysRevA.95.010103</a>

Jazyk výsledku

angličtina

Název v původním jazyce

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

Popis výsledku v původním jazyce

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. Here, we use the Lipkin-Meshkov-Glick (LMG) model as a test bed to explore the strong connection between EPs and the onset of excited state quantum phase transitions (ESQPTs). 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 alpha that lead to the EPs approach the real axis as the system size N -> infinity. 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 Pade approximants, we can extract the critical value of alpha.

Název v anglickém jazyce

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

Popis výsledku anglicky

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. Here, we use the Lipkin-Meshkov-Glick (LMG) model as a test bed to explore the strong connection between EPs and the onset of excited state quantum phase transitions (ESQPTs). 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 alpha that lead to the EPs approach the real axis as the system size N -> infinity. 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 Pade approximants, we can extract the critical value of alpha.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10301 - Atomic, molecular and chemical physics (physics of atoms and molecules including collision, interaction with radiation, magnetic resonances, Mössbauer effect)

Projekt

—

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2017

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Physical Review A

ISSN

2469-9926

e-ISSN

—

Svazek periodika

95

Číslo periodika v rámci svazku

1

Stát vydavatele periodika

US - Spojené státy americké

Počet stran výsledku

5

Strana od-do

—

Kód UT WoS článku

000398367800001

EID výsledku v databázi Scopus

2-s2.0-85011655153