Exceptional spectral phase in a dissipative collective spin model
Metadata
Show full item recordEditorial
American Physical Society
Date
2022-07-07Referencia bibliográfica
Rubio, Á... [et al.]. Exceptional spectral phase in a dissipative collective spin model. PHYSICAL REVIEW A 106, L010201 (2022). DOI: [10.1103/PhysRevA.106.L010201]
Sponsorship
MCIN/AEI PGC2018-094180-B-I00 PID2019-104002GB-C21; European Commission; CAM/FEDER Project S2018/TCS-4342; Junta de Andalucia UHU-1262561 P20-00764; CSIC Research Platform on Quantum Technologies PTI-001; La Caixa Foundation 100010434 LCF/BQ/DR21/11880024Abstract
We study a model of a quantum collective spin weakly coupled to a spin-polarized Markovian environment
and find that the spectrum is divided into two regions that we name normal and exceptional Liouvillian spectral
phases. In the thermodynamic limit, the exceptional spectral phase displays the unique property of being made
up exclusively of second-order exceptional points. As a consequence, the evolution of any initial density matrix
populating this region is slowed down and cannot be described by a linear combination of exponential decays.
This phase is separated from the normal one by a critical line in which the density of Liouvillian eigenvalues
diverges, a phenomenon analogous to that of excited-state quantum phase transitions observed in some closed
quantum systems. In the limit of no bath polarization, this criticality is transferred onto the steady state, implying
a dissipative quantum phase transition and the formation of a boundary time crystal.