Ultra-sensitive solid-state organic molecular microwave quantum receiver

TL;DR

This paper introduces a highly sensitive microwave quantum receiver using organic molecular spins and maser technology, achieving sensitivity levels over three orders of magnitude better than inorganic counterparts at ambient conditions.

Contribution

It presents a novel organic molecular spin-based microwave receiver with enhanced sensitivity and bandwidth, surpassing inorganic systems and enabling practical quantum sensing applications.

Findings

Achieved sensitivity of 6.14 fT/√Hz, exceeding inorganic systems by over three orders of magnitude.

Implemented heterodyne detection to improve bandwidth and enable frequency detection.

Demonstrated potential for applications in ESR spectroscopy, dark matter searches, and astronomy.

Abstract

High-accuracy microwave sensing is widely demanded in various fields, ranging from cosmology to microwave quantum technology. Quantum receivers based on inorganic solid-state spin systems are promising candidates for such purpose because of the stability and compatibility, but their best sensitivity is currently limited to a few pT/$\sqrt{\rm{Hz}}$. Here, by utilising an enhanced readout scheme with the state-of-the-art solid-state maser technology, we develop a robust microwave quantum receiver functioned by organic molecular spins at ambient conditions. Owing to the maser amplification, the sensitivity of the receiver achieves 6.14 $\pm$ 0.17 fT/$\sqrt{\rm{Hz}}$ which exceeds three orders of magnitude than that of the inorganic solid-state quantum receivers. The heterodyne detection without additional local oscillators improves bandwidth of the receiver and allows frequency detection. The scheme can be extended to other solid-state spin systems without complicated control pulses and thus enables practical applications such as electron spin resonance spectroscopy, dark matter searches, and astronomical observations.