RT Journal Article
T1 Degeneracy in excited-state quantum phase transitions of two-level bosonic models and its influence on system dynamics
A1 Khalouf-Rivera, Jamil
A1 Wang, Qian
A1 Santos, Lea F.
A1 García Ramos, José Enrique
A1 Carvajal Zaera, Miguel
A1 Pérez Bernal, Francisco
AB Excited-state quantum phase transitions (ESQPTs) strongly influence the spectral properties of collective many-body quantum systems, changing degeneracy patterns in different quantum phases. Level  degeneracies in turn affect the system’s dynamics. We analyze the degeneracy dependence on the size of two-level boson models with a u(n + 1) dynamical algebra, where n is the number of collective degrees of freedom. Below the ESQPT critical energy of these models, the energy gap between neighboring levels that belong to different symmetry sectors gets close to zero as the system size increases. We report and explain why this gap goes to zero exponentially for systems with one collective degree of freedom but algebraically in models with more than one degree of freedom. As a consequence, we show that the infinite-time average of out-of-time-order correlators is an ESQPT order parameter in finite systems with n = 1, but in systems with n > 1, this average only works as an order parameter in the mean-field limit.
PB American Physical Society
SN 2469-9926
SN 2469-9934 (electrónico)
YR 2024
FD 2024-06
LK https://hdl.handle.net/10272/24053
UL https://hdl.handle.net/10272/24053
LA eng
NO Khalouf-Rivera, J., Wang, Q., Santos, L. F., García-Ramos, J.-E., Carvajal, M., & Pérez-Bernal, F. (2024). Degeneracy in excited-state quantum phase transitions of two-level bosonic models and its influence on system dynamics. In Physical Review A (Vol. 109, Issue 6). American Physical Society (APS). https://doi.org/10.1103/physreva.109.062219
NO This project received funding through Grant No. PID2022-136228NB-C21 funded by MICIU/AEI/10.13039/501100011033 and, as appropriate, by “ERDF A way of making Europe, by ERDF/EU,” by the European Union, or by the European UnionNextGenerationEU/PRTR. This work was also partially supported by the Consejería de Conocimiento, Investigación yUniversidad, Junta de Andalucía and European Regional Development Fund, through Grant No. UHU-1262561 (J.K.-R.and F.P.-B.) and Grant No. US-1380840 (J.K.-R.), and Grant No. PY2000764. J.K.-R. also acknowledges support from aSpanish Ministerio de Universidades “Margarita Salas” Fellowship. Computing resources supporting this work wereprovided by the CEAFMC and Universidad de Huelva High Performance Computer located in the Campus Universitario“El Carmen” and funded by FEDER/MINECO Project No. UNHU-15CE-2848.
DS Repositorio Institucional de la Universidad de Huelva
RD 1 jun 2026