Spatially Adiabatic Frequency Conversion in Optoelectromechanical Arrays

TL;DR

This paper proposes an array-based optoelectromechanical system that uses spatial adiabatic techniques to significantly enhance quantum signal conversion bandwidths beyond traditional limits, reducing noise and improving efficiency.

Contribution

The authors introduce a novel array configuration with spatially varied coupling rates enabling broadband, low-noise quantum frequency conversion through adiabatic mode transfer.

Findings

Bandwidth exceeds cavity linewidth in array configurations

Thermal noise is significantly reduced in the proposed scheme

Small arrays achieve the largest bandwidth enhancement per transducer

Abstract

Faithful conversion of quantum signals between microwave and optical frequency domains is crucial for building quantum networks based on superconducting circuits. Optoelectromechanical systems, in which microwave and optical cavity modes are coupled to a common mechanical oscillator, are a promising route towards this goal. In these systems, efficient, low-noise conversion is possible using a mechanically dark mode of the fields but the conversion bandwidth is limited to a fraction of the cavity linewidth. Here, we show that an array of optoelectromechanical transducers can overcome this limitation and reach a bandwidth that is larger than the cavity linewidth. The coupling rates are varied in space throughout the array so that the mechanically dark mode of the propagating fields adiabatically changes from microwave to optical or vice versa. This strategy also leads to significantly reduced thermal noise with the collective optomechanical cooperativity being the relevant figure of merit. Finally, we demonstrate that, quite surprisingly, the bandwidth enhancement per transducer element is largest for small arrays; this feature makes our scheme particularly attractive for state-of-the-art experimental setups.