Exceptional bound(EB)states represent a unique new class of robust bound states protected by the defectiveness of non-Hermitian exceptional points.Conceptually distinct from the more well-known topological states and ...Exceptional bound(EB)states represent a unique new class of robust bound states protected by the defectiveness of non-Hermitian exceptional points.Conceptually distinct from the more well-known topological states and non-Hermitian skin states,they were recently discovered as a novel source of negative entanglement entropy in the quantum entanglement context.Yet,EB states have been physically elusive,being originally interpreted as negative probability eigenstates of the propagator of nonHermitian Fermi gases.In this work,we show that EB states are in fact far more ubiquitous,also arising robustly in broad classes of systems whether classical or quantum.This hinges crucially on a newlydiscovered spectral flow that rigorously justifies the EB nature of small candidate lattice systems.As a highlight,we present their first experimental realization through an electrical circuit,where they manifest as prominent stable resonant voltage profiles.Our work brings a hitherto elusive but fundamentally distinctive quantum phenomenon into the realm of classical metamaterials,and provides a novel pathway for the engineering of robust modes in otherwise sensitive systems..展开更多
In this study,we investigate exact spherically symmetric Gauss-Bonnet black hole solutions surrounded by a cloud of string fluid with the cosmological constant in D>4 dimensions.Both charged and uncharged cases are...In this study,we investigate exact spherically symmetric Gauss-Bonnet black hole solutions surrounded by a cloud of string fluid with the cosmological constant in D>4 dimensions.Both charged and uncharged cases are considered.We focus on the de Sitter solutions in the main text and provide the anti-de Sitter solutions in the appendix.We analyze the features of event horizons and thermodynamic properties of the black hole solutions.The mass,Hawking temperature,thermal stability,and phase transitions are discussed.Moreover,the equation of state and critical phenomena associated with these solutions are explored.展开更多
We investigate the quasinormal mode and greybody factor of Bardeen black holes with a cloud of strings via the WKB approximation and verify them using the Prony algorithm. We find that the imaginary part of the quasin...We investigate the quasinormal mode and greybody factor of Bardeen black holes with a cloud of strings via the WKB approximation and verify them using the Prony algorithm. We find that the imaginary part of the quasinormal mode spectra is always negative, and the perturbation does not increase with time, indicating that the system is stable under scalar field perturbation. Moreover, the string parameter a has a dramatic impact on the frequency and decay rate of the waveforms. In addition, the greybody factor increases when a and λ increase and when q and l decrease. The parameters λ and l have a significant effect on the tails. In particular, when l=0, a de Sitter phase appears at the tail.展开更多
基金supported by the National Key R&D Program of China(2022YFA1404904)the National Research Foundation Singapore grant under its QEP2.0 programme(NRF2021-QEP2-02-P09)+1 种基金the Ministry of Education(MOE)Tier-II grant(MOE-T2EP502220008)supported by the SUTD-ZJU Thematic Research Grant(SUTD-ZJU(TR)202203)。
文摘Exceptional bound(EB)states represent a unique new class of robust bound states protected by the defectiveness of non-Hermitian exceptional points.Conceptually distinct from the more well-known topological states and non-Hermitian skin states,they were recently discovered as a novel source of negative entanglement entropy in the quantum entanglement context.Yet,EB states have been physically elusive,being originally interpreted as negative probability eigenstates of the propagator of nonHermitian Fermi gases.In this work,we show that EB states are in fact far more ubiquitous,also arising robustly in broad classes of systems whether classical or quantum.This hinges crucially on a newlydiscovered spectral flow that rigorously justifies the EB nature of small candidate lattice systems.As a highlight,we present their first experimental realization through an electrical circuit,where they manifest as prominent stable resonant voltage profiles.Our work brings a hitherto elusive but fundamentally distinctive quantum phenomenon into the realm of classical metamaterials,and provides a novel pathway for the engineering of robust modes in otherwise sensitive systems..
基金Supported by the National Natural Science Foundation of China(12275087)the Fundamental Research Funds for the Central Universities.
文摘In this study,we investigate exact spherically symmetric Gauss-Bonnet black hole solutions surrounded by a cloud of string fluid with the cosmological constant in D>4 dimensions.Both charged and uncharged cases are considered.We focus on the de Sitter solutions in the main text and provide the anti-de Sitter solutions in the appendix.We analyze the features of event horizons and thermodynamic properties of the black hole solutions.The mass,Hawking temperature,thermal stability,and phase transitions are discussed.Moreover,the equation of state and critical phenomena associated with these solutions are explored.
基金Supported by the National Natural Science Foundation of China (12275087)the Fundamental Research Funds for the Central Universities
文摘We investigate the quasinormal mode and greybody factor of Bardeen black holes with a cloud of strings via the WKB approximation and verify them using the Prony algorithm. We find that the imaginary part of the quasinormal mode spectra is always negative, and the perturbation does not increase with time, indicating that the system is stable under scalar field perturbation. Moreover, the string parameter a has a dramatic impact on the frequency and decay rate of the waveforms. In addition, the greybody factor increases when a and λ increase and when q and l decrease. The parameters λ and l have a significant effect on the tails. In particular, when l=0, a de Sitter phase appears at the tail.
