Su-Schrieffer-Heeger chain with one pair of $$\mathcal{P}\mathcal{T}$$-symmetric defects

Abstract

The topologically nontrivial edge states induce transition in Su-Schrieffer-Heeger (SSH) chain with one pair of gain and loss at boundaries. In this study, we investigated a pair of -symmetric defects located inside the SSH chain, in particular, the defects locations are at the chain centre. The symmetry breaking of the bound states leads to the transition, the -symmetric phases and the localized states were studied. In the broken -symmetric phase, all energy levels break simultaneously in topologically trivial phase; however, two edge states in topologically nontrivial phase are free from the influence of the -symmetric defects. We discovered -symmetric bound states induced by the -symmetric local defects at the SSH chain centre. The -symmetric bound states significantly increase the transition threshold and coalesce to the topologically protected zero mode with vanishing probabilities on every other site of the left-half chain and the right-half chain, respectively.

Topological multiband photonic superlattices

“…In photonics and plasmonics, the SSH chain can be implemented with locally coupled cavities or waveguides with two alternating tunneling constants. Consequently, the topological zero mode in 1D has been theoretically widely investigated [7][8][9][10][11][12][13][14][15][16][17][18][19][20] and observed in recent experiments [21][22][23][24][25][26][27] with various systems either at the edge of an array or at the domain wall of two arrays with different dimerizations.…”

Inversion symmetric non-Hermitian Chern insulator

“…Open systems ubiquitously exist in physics [8][9][10], particularly, the optical and photonic systems; these are mostly non-Hermitian because they interact with the environment [11][12][13][14][15][16]. Currently, topological systems extend into the non-Hermitian region , and the nontrivial topological properties are studied in one-dimensional (1D), twodimensional (2D), and three-dimensional (3D) systems, including the Su-Schrieffer-Heeger (SSH) model [45][46][47][48][49], Aubry-André-Harper (AAH) model [50][51][52][53][54][55], Rice-Mele (RM) model [56,57], Chern insulator [58][59][60][61][62], and Weyl semimetal [63,64].…”

Entangling non planar molecules via inversion doublet transition with negligible spontaneous emission

“…However, entanglement is fragile because of decoherence induced by the environment and it is essential to maintain quantum entanglement for long enough time for many applications of interest (e.g., see the work of Horodecki [9] and references therein). Since an atom seems good candidate as quantum bit (qubit), several schemes for the generation of entangled states between two atoms have been proposed, the entanglement being achieved by the coupling of the atoms to a common reservoir, or dipole-dipole interaction generated in electronic transitions including spontaneous emission, the atoms being eventually inserted in cavities or/and driven by external radiation fields [10][11][12][13][14][15][16] (we quote only some works among many others).…”