All-Optical Thermometry and Thermal Properties of the Optically Detected Spin Resonances of the NV^– Center in Nanodiamond

The negatively charged nitrogen-vacancy (NV^–) center in diamond is at the frontier of quantum nanometrology and biosensing. Recent attention has focused on the application of high-sensitivity thermometry using the spin resonances of NV^– centers in nanodiamond to subcellular 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

Spontaneous Spectral Diffusion in CdSe Quantum Dots

Spectral diffusion of the emission line of single colloidal nanocrystals is generally regarded as a random process. Here, we show that each new spectral position has a finite memory of previous spectral positions, as evidenced by persistent anticorrelations in time series of spectral jumps. The anticorrelation indicates that there is an enhanced probability of the charge distribution around the nanocrystal returning to a previous configuration. We show both statistically and directly that this memory manifests as an observable spontaneous “relaxation” in the absence of a pump laser, so that spectral diffusion progresses in a manner of “two steps forward and one step back”