  Diamond quantum thermometry exploits the optical and electrical spin
properties of colour defect centres in diamonds and, acts as a quantum sensing
method exhibiting ultrahigh precision and robustness. Compared to the existing
luminescent nanothermometry techniques, a diamond quantum thermometer can be
operated over a wide temperature range and a sensor spatial scale ranging from
nanometres to micrometres. Further, diamond quantum thermometry is employed in
several application, including electronics and biology, to explore these fields
with nanoscale temperature measurements. This review covers the operational
principles of diamond quantum thermometry for spin-based and all-optical
methods, material development of diamonds with a focus on thermometry, and
examples of applications in electrical and biological systems with demand-based
technological requirements.
