Overcoming frequency resolution limits using a solid-state spin quantum sensor

TL;DR

This paper introduces a superresolution quantum sensing method using solid-state spin sensors to distinguish nearly identical incoherent signals, surpassing traditional frequency resolution limits with improved scaling and reduced noise.

Contribution

The authors demonstrate a novel superresolution quantum sensing technique that overcomes frequency resolution limits by optimizing interrogation times and reducing noise, achieving sub-kHz resolution.

Findings

Achieved sub-kHz frequency resolution within 80 microseconds.

Demonstrated resolution scaling as t^{-2}, surpassing the standard t^{-1}.

Reduced classical readout noise using a nuclear spin enhances sensing performance.

Abstract

The ability to determine precisely the separation of two frequencies is fundamental to spectroscopy, yet the resolution limit poses a critical challenge: distinguishing two incoherent signals becomes impossible when their frequencies are sufficiently close. Here, we demonstrate a simple and powerful approach, dubbed {\it superresolution quantum sensing}, which experimentally resolves two nearly identical incoherent signals using a solid-state spin quantum sensor. By carefully choosing interrogation times that satisfy the superresolution condition, we eliminate quantum projection noise, overcoming the vanishing distinguishability of signals with near-identical frequencies. This leads to improved resolution, which scales as $t^{-2}$ in comparison to the standard $t^{-1}$ scaling. Together with a greatly reduced classical readout noise assisted by a nuclear spin, we are able to achieve sub-kHz resolution with a signal detection time of 80 microseconds. Our results highlight the potential of quantum sensing to overcome conventional frequency resolution limitations, with broad implications for precision measurements.