Diamond nanocrystals, namely nanodiamonds, which host point defects such as nitrogen-vacancy (NV) centers, are a promising quantum material.

A central requirement to realize practical applications is the placement of individual NV centers at will on integrated circuits. This is critical for implementing , leading to a number of exciting opportunities and emerging fields such as quantum computers, , and quantum metrology.

However, a flexible, universal route is still needed for achieving nanoscale accuracy, scalability, cost-effectiveness and efficient coupling with a wide range of nanophotonic circuitries.

Several methods, such as the sophisticated "pick-and-place" nanomanipulation approach, have been devised to position the nanodiamonds with NV centers on various substrates and circuits. However, this prerequisite continues to suffer from coarse positioning accuracy, low throughput, and process complexity.

The team led by Dr. Ji Tae Kim from the Department of Mechanical Engineering and Dr. Zhiqin Chu from the Electrical and Electronic Engineering of the University of Hong Kong (HKU) has developed a nano-precision printing method for nitrogen-vacancy (NV) centers in diamond at the quantum level, meeting the technological requirements.

This novel approach is practical and cost-effective, paving the way for manufacturing of quantum information processing device, and biosensing devices.

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