Nonvolatile quantum memory enables sensor unlimited nanoscale spectroscopy of finite quantum systems

TL;DR

This paper introduces a hybrid quantum-classical sensor using NV centers in diamond with a nuclear spin memory, significantly improving spectral resolution in nanoscale NMR spectroscopy to enable single-molecule analysis.

Contribution

It presents a novel quantum memory-enhanced sensor that overcomes spectral resolution limits in nanoscale NMR, enabling high-resolution spectroscopy of finite quantum systems.

Findings

Quantum and classical memory lifetimes of 8 ms and 4 minutes achieved.

High resolution NMR spectra with linewidths down to 13 Hz obtained.

Demonstrated protocols improve measurement efficiency and resolution.

Abstract

In nanoscale metrology applications, measurements are commonly limited by the performance of the sensor. Here we show that in nuclear magnetic resonance (NMR) spectroscopy measurements using single nitrogen-vacancy (NV) centers in diamond, the NV sensor electron spin limits spectral resolution down to a few hundred Hz, which constraints the characterization and coherent control of finite spin systems, and furthermore, is insufficient for high resolution NMR spectroscopy aiming at single molecule recognition and structure analysis of the latter. To overcome the limitation, we support an NV electron spin sensor with a nuclear spin qubit acting as quantum and classical memory allowing for intermediate nonvolatile storage of metrology information, while suppressing the deleterious back-action of the sensor onto the system under investigation. We demonstrate quantum and classical memory lifetimes of 8 ms and 4 minutes respectively under ambient conditions. Furthermore, we design and test measurement and decoupling protocols, which exploit such memory qubits efficiently. Using our hybrid quantum-classical sensor device, we achieve high resolution NMR spectra with linewidths of single spins down to 13 Hz. Our work is therefore a prerequisite for high resolution NMR spectroscopy on nanoscopic quantum systems down to the single level.