Anti-PT-symmetry-enhanced interconversion between microwave and optical fields

TL;DR

This paper introduces an anti-PT symmetric microwave-optical converter that leverages dissipation-induced coherence to significantly enhance conversion efficiency and exhibits nonreciprocal behavior due to intrinsic coupling asymmetries.

Contribution

It proposes a novel anti-PT symmetric converter utilizing dissipation-induced coherence, achieving improved efficiency and nonreciprocity in microwave-optical transduction.

Findings

Enhanced conversion efficiency via anti-PT symmetry.

Observation of nonreciprocal microwave-optical conversion.

Identification of a long-lived dark mode in the hybrid system.

Abstract

The intrinsic dissipation of systems into a shared reservoir introduces coherence between two systems, enabling anti-Parity-Time (anti-PT) symmetry. In this paper, we propose an anti-PT symmetric converter, consisting of a microwave cavity coupled dissipatively to a ferromagnetic sphere, which supports significant improvements in the conversion efficiency when compared to coherently coupled setups. In particular, when only the ferrite sample is driven, the strong coherence induced by the vacuum of the mediating channel leads to much stronger enhancements in the intended conversion. The enhancement is an inalienable artifact of the emergence of a long-lived, dark mode associated with a quasi-real singularity of the hybrid system. In addition, we observe considerable asymmetry in the efficiencies of microwave-to-optical and optical-to-microwave conversions, in spite of the symmetrical structure of the trilinear optomagnonic coupling stimulating both the transduction phenomena. The nonreciprocity stems from the intrinsic asymmetry in the couplings of the microwave and optical fields to the cavity-magnon network as well as the phase coupling entailed by the spatial separation.