Spontaneous PT -symmetry breaking in non-Hermitian coupled-cavity array

Abstract

We study the effects of the position of the passive and active cavities on the spontaneous parity-time (PT ) symmetry breaking behavior in non-Hermitian coupled cavities array model. We analyze and discuss the energy eigenvalue spectrums and PT symmetry in the topologically trivial and nontrivial regimes under three different cases in detail, i.e., the passive and active cavities are located at, respectively, the two end positions, the second and penultimate positions, and each position in coupled cavities array. The odevity of the number of cavities is further considered to check the effects of the non-Hermitian terms applied on the PT symmetric and asymmetric systems. We find that the position of the passive and active cavities has remarkable impacts on the spontaneous PT symmetry breaking behavior, and in each case the system exhibits distinguishable and novel spontaneous PT symmetry breaking characteristic, respectively. The effects of the non-Hermitian terms on the PT symmetric and asymmetric systems due to the odevity are comparatively different in the first case while qualitatively same in the second case.

Quantum phase transition in a non-Hermitian XY spin chain with global complex transverse field

“…The non-Hermitian term can be generated by exciting one of the metastable states to an auxiliary state [21]. Besides the cold atom experimental scheme mentioned above, the results can also be realized in coupled cavity arrays [60], in which the non Hermiticity can be realized by active and passive cavities [24,61,62].…”

Topological properties in the non-Hermitian tetramerized Su-Schrieffer-Heeger lattices

“…And in the topologically trivial phase, the system undergoes an abrupt transition from the unbroken PT -symmetry region to the spontaneously broken PT -symmetry region at a certain potential-magnitude γ c [50]. Following this work, many groups dedicate themselves to investigating the properties of PT -symmetric non-Hermitian SSH model, including the spontaneous PT -symmetry breaking, topological invariants, topological phase, harmonic oscillation at the exceptional point, and topological end states [51][52][53][54][55][56]. In experiment, the PT -symmetry breaking can be observed directly.…”

Topological Phase Transition and Eigenstates Localization in a Generalized Non‐Hermitian Su–Schrieffer–Heeger Model

“…In general, the studies of non‐Hermitian Hamiltonian initially date back to the early days of Hermitian system with parity‐time () symmetry. [ 8–12 ] A mass of novel phenomena cluster in non‐Hermitian system induced by asymmetric coupling in comparison to Hermitian system. [ 13–22 ] An important difference between Hermitian system and non‐Hermitian system caused by asymmetric coupling is that all the eigenstates are localized in non‐Hermitian system but far from it in Hermitian system, that is, non‐Hermitian skin effect.…”