Experimental Study of Active LRC Circuits with PT-Symmetries

TL;DR

This paper experimentally investigates active LRC circuits with PT-symmetry, demonstrating phase transitions from real to complex eigen-frequencies and analyzing energy evolution consequences.

Contribution

It provides the first experimental realization of PT-symmetric active circuits and explores their phase transition behavior and energy dynamics.

Findings

Eigen-frequencies undergo a spontaneous phase transition at PT-symmetry breaking.

Normal modes coalesce and acquire chirality at the transition.

Energy evolution shows distinct behaviors across the phase transition.

Abstract

Mutually coupled modes of a pair of active LRC circuits, one with amplification and another with an equivalent amount of attenuation, provide an experimental realization of a wide class of systems where gain/loss mechanisms break the Hermiticity while preserving parity-time PT symmetry. For a value PT of the gain/loss strength parameter the eigen-frequencies undergo a spontaneous phase transition from real to complex values, while the normal modes coalesce acquiring a definite chirality. The consequences of the phase-transition in the spatiotemporal energy evolution are also presented.