Quantum Fourier transform for nanoscale quantum sensing

Vadim Vorobyov,Durga Dasari,Philipp Neumann,Jonas Meinel,Sebastian Zaiser,Jörg Wrachtrup,Nikolas Abt

doi:10.1038/s41534-021-00463-6

Abstract

The quantum Fourier transformation (QFT) is a key building block for a whole wealth of quantum algorithms. Despite its proven efficiency, only a few proof-of-principle demonstrations have been reported. Here we utilize QFT to enhance the performance of a quantum sensor. We implement the QFT algorithm in a hybrid quantum register consisting of a nitrogen-vacancy (NV) center electron spin and three nuclear spins. The QFT runs on the nuclear spins and serves to process the sensor—i.e., the NV electron spin signal. Specifically, we show the application of QFT for correlation spectroscopy, where the long correlation time benefits the use of the QFT in gaining maximum precision and dynamic range at the same time. We further point out the ability for demultiplexing the nuclear magnetic resonance (NMR) signals using QFT and demonstrate precision scaling with the number of used qubits. Our results mark the application of a complex quantum algorithm in sensing which is of particular interest for high dynamic range quantum sensing and nanoscale NMR spectroscopy experiments.

Highlights

Diamond spin-based quantum sensing has advanced nanoscale sensing and in particular nuclear magnetic resonance (NMR) studies to a level where signals from zeptoliters sample volumes can be detected
We develop a metrological high dynamic range correlation protocol that is adapted to our hybrid qubit-qutrit quantum register-sensor system
As in previous work on correlation spectroscopy[12,22], it consists of two interrogation steps separated by a long correlation time Tc

Summary

Introduction

Diamond spin-based quantum sensing has advanced nanoscale sensing and in particular nuclear magnetic resonance (NMR) studies to a level where signals from zeptoliters sample volumes can be detected. The spectral resolution was too low to achieve chemical specificity, a hallmark of standard NMR. Classical and quantum protocols have achieved better than Hz spectral resolution. An additional remaining challenge is, that NMR spectra usually comprise a whole wealth of spectral components. In conventional NMR the technique most widely used to attain the required spectral resolution and simultaneously efficiently measure whole spectra is Fourier transform spectroscopy. In this method the temporal evolution of the spin system is measured and a subsequent Fourier transform yields the NMR spectrum. The question at hand is, if there is a similar quantum sensing strategy in nanoscale NMR

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Results

Conclusion