Floquet Topological Frequency-Converting Amplifier

TL;DR

This paper presents a Floquet-driven model with a modulated harmonic oscillator that achieves non-Hermitian topological amplification and frequency conversion, providing a feasible route for experimental implementation in quantum systems.

Contribution

It introduces a novel Floquet model with a modulated oscillator that realizes non-Hermitian topological effects for frequency conversion and amplification.

Findings

Directional amplification induced by nontrivial winding numbers

Synthetic lattice with Dirac cones and topological zero modes

Feasible implementation in superconducting circuits

Abstract

We introduce a driven-dissipative Floquet model in which a single harmonic oscillator, with both frequency and decay rate modulated, realizes a non-Hermitian synthetic lattice with an effective electric-field gradient in frequency space. Using the Floquet-Green's function and the doubled Hamiltonian representation of non-Hermitian matrices, we show that the linear response of this system is characterized by a local winding number. Nontrivial values of the winding number induce directional amplification in the synthetic dimension, thereby converting input signals to different frequencies. The underlying mode structure is well described by a Jackiw-Rebbi-like continuum theory with Dirac cones and solitonic topological zero modes in synthetic frequency. Our results establish a simple and experimentally feasible route to non-Hermitian topological amplification, naturally implementable in current quantum technologies such as superconducting circuits.