We study the transition of a quantum system $S $ from pure state to mixed one, which is induced by criticality surrounding $E$ coupled it. To characterize this quantitatively, we carefully examine behavior Loschmidt echo (LE) modelled as an Ising model in transverse field, behaves measuring apparatus measurement. It found that critical strongly affects its capability enhancing decay LE: near value field entailing happening phase transition, off-diagonal elements reduced density matrix...

Asymmetric coupling amplitudes effectively create an imaginary gauge field, which induces a non-Hermitian Aharonov-Bohm (AB) effect. Nonzero magnetic flux invalidates the bulk-boundary correspondence and leads to topological phase transition. However, way of non-Hermiticity appearance may alter system topology. By alternatively introducing under symmetry prevent nonzero flux, recovers every bulk state becomes extended; topology Bloch Hamiltonian predicts (non)existence edge states These are...

Topological edge states are the core of topological photonics. Here we introduce antihelical time-reversal symmetric metals and propose a photonic realization in an anisotropic square lattice coupled ring resonators, where clockwise counterclockwise modes play role pseudospins. The robustly propagate across corners toward diagonal lattice: same (opposite) pseudospins copropagate direction on parallel boundaries; different separate converge at opposite corners. metallic phase alter to helical...

We study the non-Hermitian quantum mechanics for discrete system. This paper gives an exact analytic single-particle solution $N$-site tight-binding chain with two conjugated imaginary potentials $\ifmmode\pm\else\textpm\fi{}i\ensuremath{\gamma}$ at end sites, which Hamiltonian has parity-time symmetry ($\mathcal{P}\mathcal{T}$ symmetry). Based on Bethe ansatz results, it is found that, in subspace, this model comprised of phases: unbroken phase a purely real energy spectrum region...

We propose an incident direction independent wave propagation generated by properly assembling different unidirectional destructive interferences (UDIs), which is a consequence of the appropriate match between synthetic magnetic fluxes and vector. Single-direction lasing at spectral singularity feasible without introducing nonlinearity. UDI allows perfect absorption; when they are combined in parity-time symmetric manner, singularities vanish with bounded reflections transmissions....

We show that a class of exactly solvable quantum Ising models, including the transverse-field model and anisotropic XY model, can be characterized as loops in two-dimensional auxiliary space. The corresponds to circle an ellipse, while other models yield cardioid, limacon, hypocycloid, Lissajous curves etc. It is shown variation ground state energy density, which function loop, experiences nonanalytical point when winding number corresponding loop changes. serve topological phases extended...

We propose an anti-parity-time (anti-$\mathcal{PT}$) symmetric non-Hermitian Su-Schrieffer-Heeger (SSH) model, where the large non-Hermiticity constructively creates nontrivial topology and greatly expands topological phase. In anti-$\mathcal{PT}$-symmetric SSH gain loss are alternatively arranged in pairs under inversion symmetry. The appearance of degenerate point at center Brillouin zone determines phase transition, whereas exceptional points unaffect band topology. leads to unbalanced...

We show that a perfect quantum-state transmission can be realized through spin chain possessing the commensurate structure of an energy spectrum, which is matched with corresponding parity. As exposition mirror inversion symmetry discovered by Albanese et al. (e-print quant-ph∕0405029), parity commensurability spectra helps us to present preengineered systems for quantum information transmission. Based on these theoretical analyses, we propose protocol near-perfect transfer using...

We explore the physical mechanism to coherently transfer quantum information of spin by connecting two spins an isotropic antiferromagnetic ladder system as data bus. Due a large gap existing in such perfect medium, effective Hamiltonian connected can be archived that Heisenberg type, which possesses ground state with maximal entanglement. show coupling strength is inversely proportional distance and thus transferred between separated longer distance, i.e., characteristic time quantum-state...

We systematically study a Kitaev chain with imbalanced pair creation and annihilation, which is introduced by non-Hermitian pairing terms. An exact phase diagram shows that the topological still robust under influence of conditional imbalance. The gapped phases are characterized invariant, extended Zak phase, defined biorthonormal inner product. Such destroyed at points where coalescence ground states occurs, associated time-reversal symmetry breaking. find Majorana edge modes also exist in...

The topologically nontrivial edge states induce [Formula: see text] transition in Su-Schrieffer-Heeger (SSH) chain with one pair of gain and loss at boundaries. In this study, we investigated a text]-symmetric defects located inside the SSH chain, particular, locations are centre. symmetry breaking bound leads to transition, phases localized were studied. broken phase, all energy levels break simultaneously trivial phase; however, two phase free from influence defects. We discovered induced...

ZIF-8 film coated meshes with an oil–water separation efficiency of up to 99.99% and a high flux 50 L m⁻² s⁻¹.

We study a two coupled Su-Schrieffer-Heeger (SSH) chains system, which is shown to contain rich quantum phases associated with topological invariants protected by symmetries. In the weak coupling region, system supports nontrivial insulating phases, characterized winding number $\mathcal{N}=\ifmmode\pm\else\textpm\fi{}1$, and types of edge states. The boundary between arises from band closing points, exhibit characteristics in one-dimensional $k$ space. By mapping Bloch states on vector...

Ordered mesoporous carbon (OMC) is considered to be a prospective carbon-based material for microwave absorption because of its abundant well-ordered structures, high specific surface area, numerous active sites, and facile preparation process. However, development has been seriously hindered by poor impedance-matching characteristic. Herein, silica-modified OMC composites with designable transition layer are successfully fabricated via self-assembly method succeeding calcination treatment....

We employ the intertwining operator technique to synthesize a supersymmetric (SUSY) array of arbitrary size $N$. The synthesized SUSY system is equivalent spin $(N\ensuremath{-}1)/2$ under an effective magnetic field. By considering additional imaginary field, we obtain generalized parity-time-symmetric non-Hermitian Hamiltonian that describes coupled resonators or waveguides gradient gain and loss; all $N$ energy levels coalesce at exceptional point (EP), forming isotropic high-order EP...

Non-Hermiticity can vary the topology of system, induce topological phase transitions, and even invalidate conventional bulk-boundary correspondence. Here, we show introduction non-Hermiticity without affecting properties original chiral symmetric Hermitian systems. Conventional correspondence holds; transition (non)existence edge states are unchanged though energy bands inseparable due to non-Hermitian transitions. The Chern number for generalized system in two dimensions is proved be...