Much of the motivation for exploring nitrogen-vacancy (NV) centers in diamond in the past decade has been for their potential as a solid-state alternative to trapped ions for quantum computing. In this area, the NV center has exceeded expectations and even shown an unprecedented capability to perform certain quantum processing and storage operations at room temperature. The ability to operate in ambient conditions, combined with the atom-like magnetic Zeeman sensitivity, has also led to intensive investigation of NV centers as nanoscale magnetometers. Thus, aside from room-temperature solid-state quantum computers, the NV could also be used to image individual spins in biological systems, eventually leading to a new level of understanding of biomolecular interactions in living cells.

The exotic features of quantum mechanics have the potential to revolutionize information technologies. Using superposition and entanglement, a quantum processor could efficiently tackle problems inaccessible to current-day computers. Nonlocal correlations may be exploited for intrinsically secure communication across the globe. Finding and controlling a physical system suitable for fulfilling these promises is one of the greatest challenges of our time. The nitrogen-vacancy (NV) center in diamond has recently emerged as one of the leading candidates for such quantum information technologies thanks to its combination of atom-like properties and solid-state host environment. We review the remarkable progress made in the past years in controlling electrons, atomic nuclei, and light at the single-quantum level in diamond. We also discuss prospects and challenges for the use of NV centers in future quantum technologies.

The nitrogen-vacancy (NV) center in diamond offers the opportunity to develop quantum technologies that leverage the defect’s atom-like properties using established engineering techniques from the semiconductor industry. While many NV center applications are motivated by the remarkable properties of isolated NV centers in bulk diamond, realizing these technologies requires addressing a number of device and materials engineering challenges unique to creating and controlling individual semiconductor spins. We review recent advances in interfacing NV centers with on-chip electronics that enable control over the defect’s spin and orbital degrees of freedom and review fabrication techniques for creating single NV centers with nanometer-scale placement accuracies. We also discuss efforts, motivated by the success of diamond NV center applications, to identify defect spins with similar properties to the NV center in more technologically mature semiconductors such as SiC.

Advances in nanotechnology have enabled the opportunity to fabricate nanoscale optical devices and chip-scale systems in diamond that can generate, manipulate, and store optical signals at the single-photon level. In particular, nanophotonics has emerged as a powerful interface between optical elements such as optical fibers and lenses, and solid-state quantum objects such as luminescent color centers in diamond that can be used effectively to manipulate quantum information. While quantum science and technology has been the main driving force behind recent interest in diamond nanophotonics, such a platform would have many applications that go well beyond the quantum realm. For example, diamond’s transparency over a wide wavelength range, large third-order nonlinearity, and excellent thermal properties are of great interest for the implementation of frequency combs and integrated Raman lasers. Diamond is also an inert material that makes it well suited for biological applications and for devices that must operate in harsh environments.

Defects in solid-state systems are responsible for much of what we take for granted in modern society, with applications ranging from electronics and lasers, to metallic alloys with tailored properties, and the unique characteristics of gemstones. As we enter the age of quantum technology, solid-state defects are also having their say, with substantial research focused on using their properties for fundamental tests of quantum mechanics, storage of quantum information, and investigations of quantum decoherence. Two of the most exciting prospects of quantum technology are the creation of computers that take advantage of quantum rather than classical laws to outperform current devices, and the realization of highly sensitive magnetometers limited only by quantum uncertainty. In pursuit of these two goals, many proposals and proof-of-principle experiments have been performed in the solid-state, which required location of defects very close to the host crystal’s surface. This article reviews recent work on creation of nitrogen-vacancy centers near the diamond surface and experiments toward the realization of these goals.

Nitrogen-vacancy (NV) color centers in diamond are currently considered excellent solid-state magnetic field sensors. Their long coherence times at room temperature and their atomic size allow for achieving both high magnetic field sensitivity and nanoscale spatial resolution in ambient conditions. This article reviews recent progress in magnetic field imaging with NV centers. We focus on two topics: scanning probe techniques with single NV centers and their application in the imaging of nanoscale magnetic structures, as well as recent development of magnetometers with ensembles of NV centers, which image magnetic fields at micron-length scales with extremely high sensitivities.

The use of the nitrogen-vacancy (NV) center in diamond as a single spin sensor or magnetometer has attracted considerable interest in recent years because of its unique combination of sensitivity, nanoscale resolution, and room temperature operation. These properties, together with long-term photostability of the NV fluorescence and the inherent biocompatibility of diamond, make the NV system ideal for applications in biology. This article focuses on the role of the NV center in biological applications from optical tracking to nanoscale sensing.

Biological materials are effectively synthesized, controlled, and used for a variety of purposes in Nature—in spite of limitations in energy, quality, and quantity of their building blocks. Whereas the chemical composition of materials in the living world plays some role in achieving functional properties, the way components are connected at different length scales defines what material properties can be achieved, how they can be altered to meet functional requirements, and how they fail in disease states and other extreme conditions. Recent work has demonstrated this using large-scale computer simulations to predict materials properties from fundamental molecular principles, combined with experimental work and new mathematical techniques to categorize complex structure-property relationships into a systematic framework. Enabled by such categorization, we discuss opportunities based on the exploitation of concepts from distinct hierarchical systems that share common principles in how function is created, even linking music to materials science.