arXiv subjects

Artem S. Pilipchuk

Publications and source records attributed to Artem S. Pilipchuk.

3 recordsLinked to original sources

arXiv2017

Tuning of bound states in the continuum by waveguide rotation

We consider acoustic wave transmission in non axisymmetric waveguide which consists of cylindrical resonator and two semi-infinite cylindrical waveguides whose axes are shifted relative to the resonator axis and each other by azimuthal angle $Δϕ$. We show that for rotation of one of attached waveguides the coupling matrix elements of the eigenmodes of resonator classified by the integer $m$ and propagating mode of the waveguide acquire phase factor $e^{imΔϕ}$. That crucially effect Fano resonances and creates an analog of faucet opening and closing wave flux under rotation of the waveguide. We show that under the rotation of the waveguide and variation of the length of resonator numerous bound states in the continuum occur complimenting by the Fano resonance collapse.

physics.app-ph↗

arXiv2015

Coupled mode theory for acoustic resonators

We develop the effective non-Hermitian Hamiltonian approach for open systems with Neumann boundary conditions. The approach can be used for calculating the scattering matrix and the scattering function in open resonator-waveguide systems. In higher than one dimensions the method represents acoustic coupled mode theory in which the scattering solution within an open resonator is found in the form of expansion over the eigenmodes of the closed resonator decoupled from the waveguides. The problem of finding the transmission spectra is reduced to solving a set of linear equations with a non-Hermitian matrix whose anti-Hermitian term accounts for coupling between the resonator eigenmodes and the scattering channels of the waveguides. Numerical applications to acoustic two-, and three-dimensional resonator-waveguide problems are considered.

quant-ph↗

arXiv2015

Gate controlled resonant widths in double-bend waveguides: Bound states in the continuum

We consider quantum transmission through double-bend $Π$- and $Z$-shaped waveguides controlled by the finger gate potential. Using the effective non-Hermitian Hamiltonian approach we explain the resonances in transmission. We show a difference in transmission in the short waveguides that is the result of different chirality in $Z$ and $Π$ waveguides. We show that the potential selectively affects the resonant widths resulting in the occurrence of bound states in the continuum.

cond-mat.mes-hall↗