The Lukin group's technology provides a way to characterize the properties of atomically-thin samples of 2D materials (e.g., hexagonal boron-nitride, graphene, transition metal dichalcogenides), using nuclear quadrupole resonance (NQR). NQR is a standard technique for chemical and materials analysis, in which nuclear resonances are probed by microwave radiation to determine the electronic properties and bonding structure of solids. However, conventional NQR relies on inductive coils to detect the microwave-frequency signal from macroscopic samples, and is not sensitive enough to measure atomically-thin layers.

To overcome the sensitivity limitation, the present invention employs an individual nitrogen-vacancy (NV) center in diamond to detect the microwave-frequency signal. The NV center is created very close to the diamond surface (depth < 10 nm), and the sample of 2D material is placed directly on the diamond surface. The NV center is probed using a combination of microwaves and laser light so as to maximize sensitivity to the NQR frequencies of interest. The proximity of the sensor to the sample greatly boosts sensitivity, enabling detection of NQR signals even from samples that are only a few atomic layers thick.

This research was recently published in Science.