近日，美国普林斯顿大学de Leon, Nathalie P.团队报道了利用纠缠态增强多量子位纳米级传感。2025年11月26日出版的《自然》杂志发表了这项成果。

金刚石中的氮空位（NV）中心作为局部磁传感器被广泛应用，通过单量子比特控制可测量时均磁场和噪声，具有纳米级空间分辨率。扩展至多量子比特控制可催生新型传感模式，例如测量非局域时空关联量或利用纠缠态增强测量灵敏度。

研究组描述了利用光谱不可分辨的NV中心对及核自旋作为多量子比特传感器，在纳米尺度测量相关噪声的方案。对于非相互作用的NV中心，他们实现了相位循环方案，通过引入第三个量子比特——¹³C核自旋——来区分磁关联与方差波动，该方案通过相干单NV自旋翻转实现相位循环，即使NV中心光谱不可分辨且取向一致。

对于约10纳米尺度，研究组通过两个NV中心的偶极-偶极耦合制备最大纠缠的贝尔态，并利用这些纠缠态直接读取磁场关联，而非通过独立测量非纠缠态NV中心来重构。这将灵敏度对读出噪声的标度从二次方降为线性。对于常规非共振读出（其读出噪声约为量子投影极限的30倍），灵敏度提升超过一个数量级。最后，研究组展示了检测强相互作用NV中心对的高时空分辨率关联量的方法。

附：英文原文

Title: Multi-qubit nanoscale sensing with entanglement as a resource

Author: Rovny, Jared, Kolkowitz, Shimon, de Leon, Nathalie P.

Issue&Volume: 2025-11-26

Abstract: Nitrogen vacancy (NV) centres in diamond are widely deployed as local magnetic sensors, using single-qubit control to measure both time-averaged fields and noise with nanoscale spatial resolution1. Moving beyond single qubits to multi-qubit control enables new sensing modalities such as measuring nonlocal spatiotemporal correlators2 or using entangled states to enhance measurement sensitivity3. Here we describe protocols for using optically unresolved NV centre pairs and nuclear spins as multi-qubit sensors for measuring correlated noise at nanometre length scales. For noninteracting NV centres, we implement a phase-cycling protocol that disambiguates magnetic correlations from variance fluctuations, leveraging the presence of a third qubit, a 13C nucleus, to effect coherent single-NV spin flips and enable phase cycling even for co-aligned NV centres that are spectrally unresolved. For length scales around 10nm, we create maximally entangled Bell states through dipole–dipole coupling between two NV centres and use these entangled states to directly read out the magnetic field correlation, rather than reconstructing it from independent measurements of unentangled NV centres. Importantly, this changes the scaling of sensitivity with readout noise from quadratic to linear. For conventional off-resonant readout of the NV centre spin state (for which the readout noise is roughly 30 times the quantum projection limit), this results in more than an order of magnitude improvement in sensitivity. Finally, we demonstrate methods for detecting high spatial- and temporal-resolution correlators with pairs of strongly interacting NV centres.

DOI: 10.1038/s41586-025-09760-y

Source: https://www.nature.com/articles/s41586-025-09760-y