Placing a sensor close to the target at the nano-level is a central challenge in quantum sensing. We demonstrate magnetic field imaging with a boron vacancy (VB−) defects array in hexagonal boron nitride with a few 10 nm thickness. VB− sensor spots with a size of (100 nm)2 are arranged periodically with nanoscale accuracy using a helium ion microscope and attached tightly to a gold wire. The sensor array allows us to visualize the magnetic field induced by the current in the straight micro wire with a high spatial resolution. Each sensor exhibits a practical sensitivity of 73.6 μT/Hz0.5, suitable for quantum materials research. Our technique of arranging VB− quantum sensors periodically and tightly on measurement targets will maximize their potential.
We demonstrate vector magnetometry using ensemble of the nitrogen-vacancy (NV) centers in diamond that are perfectly aligned along the [111] direction. By changing the direction and strength of the reference magnetic field, we perform three-dimensional vector measurement of the Oersted field generated by the current flowing in a nearby wire. We had a formula for evaluating the magnetic field sensitivity in the direction perpendicular to the NV axis. We demonstrate that the expected sensitivity is 1.2 times higher than that of the NV ensemble isotropically oriented on four equivalent crystal axes. Our precise method is suitable for time-varying magnetic signals.
Nanodiamonds can be excellent quantum sensors for local magnetic field measurements. We demonstrate magnetic field imaging with high accuracy of 1.8 $$\upmu $$
μ
T combining nanodiamond ensemble (NDE) and machine learning without any physical models. We discover the dependence of the NDE signal on the field direction, suggesting the application of NDE for vector magnetometry and the improvement of the existing model. Our method enhances the NDE performance sufficiently to visualize nano-magnetism and mesoscopic current and expands the applicability of NDE in arbitrarily shaped materials, including living organisms. This accomplishment bridges machine learning to quantum sensing for accurate measurements.
Placing a sensor close to the target at the nano-level is a central challenge in quantum sensing. We demonstrate high-spatial-resolution magnetic field imaging with a
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