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Multi-qubit nanoscale sensing with entanglement as a resource
Jared Rovny1, Shimon Kolkowitz2, Nathalie P de Leon3
1Department of Electrical and Computer Engineering, Princeton University, Princeton, NJ, USA.
Nature
|November 26, 2025
Summary
Researchers developed multi-qubit sensors using nitrogen vacancy (NV) centers in diamond for nanoscale magnetic noise measurements. This advancement enhances sensitivity and spatial resolution for correlated magnetic field detection.
Area of Science:
- Quantum sensing
- Diamond magnetometry
- Nanoscale physics
Background:
- Nitrogen vacancy (NV) centers in diamond are established nanoscale magnetic field sensors.
- Single-qubit control enables measurement of time-averaged fields and noise.
- Multi-qubit control offers advanced sensing capabilities like nonlocal correlators and enhanced sensitivity via entanglement.
Purpose of the Study:
- To describe protocols for using optically unresolved NV center pairs and nuclear spins as multi-qubit sensors.
- To measure correlated magnetic noise at nanometre length scales.
- To enhance sensitivity and spatial resolution in magnetic field correlation measurements.
Main Methods:
- Implementation of a phase-cycling protocol for noninteracting NV centers using a 13C nucleus qubit.
- Creation of entangled Bell states via dipole-dipole coupling for direct readout of magnetic field correlations.
- Demonstration of methods for detecting high spatial- and temporal-resolution correlators with interacting NV center pairs.
Main Results:
- Disambiguation of magnetic correlations from variance fluctuations in noninteracting NV centers.
- Achieved linear scaling of sensitivity with readout noise for entangled states, improving sensitivity by over an order of magnitude.
- Demonstrated detection of high spatial- and temporal-resolution magnetic field correlators.
Conclusions:
- Multi-qubit sensing with NV centers and nuclear spins enables precise measurement of correlated magnetic noise at the nanoscale.
- Entangled states significantly enhance measurement sensitivity compared to independent measurements.
- The developed protocols open new avenues for nanoscale magnetic sensing applications.
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