Observation of Asymmetric Transport in Structures with Active Nonlinearities

TL;DR

This paper demonstrates and analyzes asymmetric wave transport in coupled nonlinear oscillators with PT symmetry, showing how gain/loss parameters influence transmission asymmetry and intensity.

Contribution

It introduces a novel mechanism for asymmetric transport based on PT symmetry combined with nonlinearity, supported by experimental and theoretical analysis.

Findings

Asymmetric transport increases with gain/loss strength.

Adding more PT-symmetric dimers enhances asymmetry.

Transmittance intensity also increases with nonlinearity.

Abstract

A mechanism for asymmetric transport based on the interplay between the fundamental symmetries of parity (P) and time (T) with nonlinearity is presented. We experimentally demonstrate and theoretically analyze the phenomenon using a pair of coupled van der Pol oscillators, as a reference system, one with anharmonic gain and the other with complementary anharmonic loss; connected to two transmission lines. An increase of the gain/loss strength or the number of PT-symmetric nonlinear dimers in a chain, can increase both the asymmetry and transmittance intensities.