arXiv subjects

Changhao Meng

Publications and source records attributed to Changhao Meng.

3 recordsLinked to original sources

arXiv2026

Non-Hermitian Skin Effect from Radiative Coupling in a Reciprocal Chiral Medium

We find that long-range radiative coupling through a passive reciprocal chiral medium produces an unusual non-Hermitian skin effect in a chain of electric dipoles. Although the system is reciprocal, the chirality generates polarization-dependent phase accumulation and attenuation, leading to degenerate pairs of skin modes localized at opposite boundaries. We find that the skin mode profile consists of an exponential contribution from an isolated complex-$\beta$ pole and a longer-range tail proportional to $1/[n(\ln n)^2]$, where $n$ is the distance from the occupied boundary measured in lattice sites. Finite-chain calculations show that part of the OBC spectrum contracts toward the Bloch spectrum, whereas the number of boundary-localized modes remains extensive.

cond-mat.other↗

arXiv2024

Non-hermitian magnonic knobbing between electromagnetically induced reflection and transparancy

Manipulation of wave propagation through open resonant systems has attracted tremendous interest. When accessible to the open system, the system under study is prone to tempering to out of equilibrium, and a lack of reciprocity is the rule rather than the exception. Open systems correspond to non-hermitian Hamiltonians with very unique properties such as resulting exceptional points and ideal isolation. Here, we have found a highly sensitive modulation for the intersection of resonant patch antennas with respect to cavity magnonic coupling by means of an open coupling system of three resonant modes. Two types of crossings are implemented in this study: the first type of crossing remotely controls the sharp switching of the transmission line 's transmittance, while regulating the repulsive behavior of its zero-reflection states. The second type of crossing corresponds to the modulation of non-reciprocal phase transitions, which enables a more desirable isolation effect. Three different coupling models are realized by a non-Hermitian scattering Hamiltonian, revealing distinct spatial overlaps between modes. This elucidates that dissipative coupling of at least two modes to the environment is crucial for non-reciprocal transport. Our work not only reveals the versatility of cavity magnonic systems but also provides a way to design functional devices for general wave optics using patch antenna crossings.

physics.app-ph↗

arXiv2023

Dyadic Green Function Approach to Multichromophoric Forster Resonance Energy Transfer under Electromagnetic Fluctuations near Metallic Thin Films

The near-field spectroscopic information is critically important to determine the Forster resonant energy transfer(FRET) rate and the distance dependence in the vicinity of metal surfaces. The high density of evanescent near-field modes in the vicinity of a metal surface can strongly modulate the FRET in multichromophoric systems. Based on the previous generalized FRET [A. Poudel, X. Chen and M. Ratner, J. Phys. Chem. Lett. 7(2016) 955], the theory of FRET is generalized for the multichromophore aggregates and nonequilibrium situations in the vicinity of evanescent surface electromagnetic waves of nanophotonic structures. The classic dyadic green function (DGF) approach to multichromophoric FRET (MC-FRET) in the existence of evanescent near-field is established. The classic DGF approach provides a microscopic understanding of the interaction between the emission and absorption spectral coupling and the evanescent electromagnetic field. The MC-FRET of the ring structures demonstrates complicated distance dependence in the vicinity of the silver thin film. Given the analytic expression of hyperbolic multi-layer thin film, the generalized coupling due to the metallic thin film is determined by the scattering DGF above the metal surface. The decomposition of the reduced scattering DGF by ignoring $S$ wave in the evanescent wave shows how the interface of the metallic thin films modulates the MC-FRET.

physics.chem-ph↗