Nanoscale diamond quantum sensors for many-body physics

Nitrogen vacancy (NV) centre quantum sensors provide unique opportunities in studying condensed matter systems, as they are quantitative, non-invasive, physically robust, offer nanoscale resolution and may be used across a wide range of temperatures. These properties have been exploited in recent years to obtain nanoscale resolution measurements of static magnetic fields arising from spin order and current flow in condensed matter systems. Compared with other nanoscale magnetic-field sensors, NV centres have the advantage that they can probe quantities that go beyond average magnetic fields. Leveraging techniques from magnetic resonance, NV centres can perform high-precision noise sensing and have given access to diverse systems, such as fluctuating electrical currents in simple metals and graphene, as well as magnetic dynamics in yttrium iron garnet. In this Technical Review, we provide an overview of NV sensing platforms and modalities and discuss the connections between specific NV measurements and important physical characteristics in condensed matter, such as correlation functions and order parameters, that are inaccessible by other techniques. We conclude with our perspectives on the new insights that may be opened up by NV sensing in condensed matter.