Radiofrequency receiver based on isotropic solid-state spins

TL;DR

This paper introduces an isotropic solid-state spin system in hexagonal boron nitride that functions as a versatile RF-optical transducer, enabling simplified, wideband RF detection and spectrum analysis without precise magnetic field alignment.

Contribution

The work demonstrates a novel isotropic spin platform in hBN for RF sensing, allowing frequency tunability and wideband spectrum analysis independent of magnetic field orientation.

Findings

Achieved RF frequency tuning from 0.1 to 19 GHz.

Implemented a wideband RF spectrum analyser using magnetic field gradients.

Successfully detected Wi-Fi signals using the spectrum analyser.

Abstract

Optically addressable solid-state spins have been proposed as robust radiofrequency (RF)-optical transducers sensitive to a specific RF frequency tuned by an external static magnetic field, but often require precise field alignment with the system's symmetry axis. Here we introduce an isotropic solid-state spin system, namely weakly coupled spin pairs in hexagonal boron nitride (hBN), which acts as an RF-optical transducer independent of the direction of the tuning magnetic field, allowing greatly simplified experimental design. Using this platform, we first demonstrate a single-frequency RF receiver with frequency tunability from 0.1 to 19 GHz. We next demonstrate an instantaneous wideband RF spectrum analyser by applying a magnetic field gradient to encode RF frequency into spatial position. Finally, we utilise the spectrum analyser to detect free-space-transmitted RF signals matching the strength and frequency of typical Wi-Fi signals. This work exemplifies the unique capabilities of isotropic spins in hBN to operate as RF sensors, while circumventing the challenging requirement of precisely aligned magnetic fields facing conventional solid-state spins.