To use quantum systems as sensors, it is crucial to bring them into a desired quantum state. Quantum optimal control (QOC) is an efficient way of doing so while using practical quantum systems and considering their limitations. Rembold et al. compiled an introductory review on how to implement QOC using nitrogen vacancy (NV) centers in diamonds as the quantum system.

“NV centers are a promising candidate for a number of quantum technological applications, especially as the building blocks for quantum sensing and communication,” said author Elke Neu. “Research in these fields has the potential to enhance medical imaging technology, make communication safer and improve methods to characterize novel materials, like superconductors or 2D materials.”

The authors chose to focus their review on QOC using NV centers in diamonds because of their stability, long spin coherence time, unique optical properties and ability to increase precision in qubit control. NV centers can also be used at room temperature and are biocompatible.

“Mathematical strategies, such as QOC, open ways to enhance the technologies without the need for drastic hardware updates,” said Neu. “It takes the investigation of both the quantum systems itself as well as control strategies to push the technology to its limits. This needs a joint effort of theory and experiment, which we are pursuing through the QuSco network.”

The review covers the properties of NV centers in diamonds, quantum sensing techniques, quantum technology applications of nitrogen vacancy centers, and the principles and methods of QOC theory.

NV centers have been used in a wide variety of applications, from biological to geological applications. The authors believe, when combined with quantum optimal control, the scope of applications will continue to broaden.

Source: “Introduction to quantum optimal control for quantum sensing with nitrogen-vacancy centers in diamond,” by Phila Rembold, Nimba Oshnik, Matthias M. Müller, Simone Montangero, Tommaso Calarco, and Elke Neu, AVS Quantum Science (2020). The article can be accessed at https://doi.org/10.1116/5.0006785.