Widefield quantum microscopy with nitrogen-vacancy centers in diamond: strengths, limitations, and prospects

Abstract

A dense layer of nitrogen-vacancy (NV) centers near the surface of a diamond can be interrogated in a widefield optical microscope to produce spatially resolved maps of local quantities such as magnetic field, electric field and lattice strain, providing potentially valuable information about a sample or device placed in proximity. Since the first experimental realization of such a widefield NV microscope in 2010, the technology has seen rapid development and demonstration of applications in various areas across condensed matter physics, geoscience and biology. This Perspective analyzes the strengths and shortcomings of widefield NV microscopy in order to identify the most promising applications and guide future development. We begin with a brief review of quantum sensing with ensembles of NV centers, and the experimental implementation of widefield NV microscopy. We then compare this technology to alternative microscopy techniques commonly employed to probe magnetic materials and charge flow distributions. Current limitations in spatial resolution, measurement accuracy, magnetic sensitivity, operating conditions and ease of use, are discussed. Finally, we identify the technological advances that solve the aforementioned limitations, and argue that their implementation would result in a practical, accessible, high-throughput widefield NV microscope.

An Integrated Widefield Probe for Practical Diamond Nitrogen-Vacancy Microscopy

“…Magnetic imaging using nitrogen-vacancy (NV) centers in diamond 1 has proven to be a valuable technique for studying the magnetic and electronic properties of materials and devices 2,3 . One particular approach, widefield NV microscopy, involves imaging an ensemble of NVs residing in a thin ( 1 µm) layer within the diamond, whose spin states are read out via their optically detected magnetic resonance (ODMR) spectrum with a camera to map the stray magnetic field of a proximal sample [4][5][6] . This technique has found utility in imaging a wide array of devices [7][8][9][10][11][12][13][14][15] , as well as biological [16][17][18][19] and geological [20][21][22] samples.…”

“…This technique has found utility in imaging a wide array of devices [7][8][9][10][11][12][13][14][15] , as well as biological [16][17][18][19] and geological [20][21][22] samples. While greater spatial resolution is achievable using scanning NV microscopy 2,3 , the parallel operation and high magnetic sensitivity of the widefield modality makes it well-suited to rapid, multipurpose diagnostic imaging of magnetic materials and devices 6 . However, its ease of use and potential for highthroughput imaging is often limited in practice by the requirement that the NV layer (and hence diamond sensor) be placed in close proximity with the sample.…”

“…Departures from flatness such as sample surface features or contaminants will cause misalignment between the diamond and sample surfaces resulting in standoffs which can significantly reduce image resolution. Broadly speaking, there are two ways to interface the diamond sensor with the sample 6 . In the first case, termed "sample-on-diamond", the sample is fabricated directly onto the diamond surface.…”