Switchable Non-Hermitian Skin Effect in Bogoliubov Modes

TL;DR

This paper demonstrates a nonlinear circuit system where Bogoliubov modes exhibit a switchable non-Hermitian skin effect, tunable by driving amplitude, without requiring asymmetric hopping nonlinearities.

Contribution

The study introduces a driven-dissipative circuit that shows a switchable NHSE in Bogoliubov modes, highlighting a new way to control non-Hermitian topological phenomena.

Findings

Switchable NHSE appears above a threshold driving voltage.

The system exhibits non-Hermitian topology in Bogoliubov modes.

No asymmetric hopping nonlinearities are needed, only local Kerr nonlinearity.

Abstract

Interacting or nonlinear lattices can host emergent particle-like modes, such as Bogoliubov quasiparticles, whose band topology and other properties are potentially highly tunable. Despite originating in the study of superconducting materials, Bogoliubov quasiparticles can also occur in synthetic metamaterials. Here, we implement a nonlinear driven-dissipative circuit whose fluctuations are Bogoliubov modes possessing nontrivial non-Hermitian band topology. We show experimentally that the system exhibits a switchable non-Hermitian skin effect (NHSE), which abruptly appears when the on-site driving voltage amplitude exceeds a threshold. In contrast to earlier realizations of the NHSE and related phenomena in circuit models, the switchable NHSE in our system occurs in Bogoliubov modes, which are strongly affected by how the system is driven. Moreover, unlike other experimental platforms hosting non-Hermitian Bogoliubov modes, our system does not contain unconventional asymmetric hopping nonlinearities, only a local Kerr-type nonlinearity.