  The negatively-charged nitrogen-vacancy (NV) center in diamond is at the
frontier of quantum nano-metrology and bio-sensing. Recent attention has
focused on the application of high-sensitivity thermometry using the spin
resonances of NV centers in nano-diamond to sub-cellular biological and
biomedical research. Here, we report a comprehensive investigation of the
thermal properties of the center's spin resonances and demonstrate an alternate
all-optical NV thermometry technique that exploits the temperature dependence
of the center's optical Debye-Waller factor.
