Radiation-free and non-Hermitian topology inertial defect states of on-chip magnons

TL;DR

This paper demonstrates radiation-free, inertial defect states in on-chip magnon arrays that are robust against non-Hermitian topology, promising for high-fidelity magnon quantum information storage.

Contribution

It introduces a novel on-chip magnonic defect state that suppresses radiation and remains inertial to non-Hermitian topology, enhancing quantum information applications.

Findings

Magnon defect states strongly localize and suppress radiation.

Radiation of defect states exponentially decreases with distance from edges.

Defect states are inert to non-Hermitian topological effects.

Abstract

Radiative damping is a strong dissipation source for the quantum emitters hybridized with propagating photons, electrons, or phonons, which is not easily avoidable for on-chip magnonic emitters as well that can radiate via the surface acoustic waves of the substrate. Here we demonstrate in an array of on-chip nano-magnets coupled in a long range via exchanging the surface acoustic waves that a point defect in the array, which can be introduced by the local magnon frequency shift by a local biased magnetic field or the absence of a magnetic wire, strongly localizes the magnons, in contrast to the well spreading Bloch-like collective magnon modes in such an array setting. The radiation of the magnon defect states is exponentially suppressed by the distance of the defect to the array edges. Moreover, this defect state is strikingly inertial to the non-Hermitian topology that localizes all the extended states at one boundary. Such configuration robust magnon defect states towards radiation-free limit may be suitable for high-fidelity magnon quantum information storage in the future on-chip magnonic devices.