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We use crystalline silicon (Si) antennas to efficiently extract broadband single-photon fluorescence from shallow nitrogen-vacancy (NV) centers in diamond into free space. Our design features relatively easy-to-pattern high-index Si resonators on the diamond surface to boost photon extraction by overcoming total internal reflection and Fresnel reflection at the diamond-air interface, and providing modest Purcell enhancement, without etching or otherwise damaging the diamond surface. In simulations, ~20 times more single photons are collected from a single NV center compared to the case without the antenna; in experiments, we observe an enhancement of ~4 times, limited by spatial alignment between the NV and the antenna. Our approach can be readily applied to other color centers in diamond, and more generally to the extraction of light from quantum emitters in wide-bandgap materials. 

We propose a platform for the study of collective emission in a solid-state system, consisting of silicon-vacancy (SiV) centers implanted in subwavelength ordered arrays. Numerical simulations of emitter-emitter interactions, fabrication, and preliminary characterization are presented. 

Nitrogen vacancy centers in diamond are used to image electron pathways in corroded zirconium alloys, with preliminary data showing unexpected luminescence from the oxidized zirconium. Our ongoing work includes identifying the origin of this luminescence. 

In nanoparticle-assisted photothermal microscopy, absorption of radiation by a nanoparticle is followed by non-radiative relaxation which leads to changes in the surrounding medium temperature, pressure, and density. Under harmonically modulated irradiation, the finite heat diffusion rate causes a phase delay between the thermal oscillation at a location in the medium relative to that at the nanoparticle surface. The phase delay averaged over the probe laser volume can be measured concomitantly with the amplitude of detected probe power modulation. In this study we show that, in conjunction with the more widespread measurement of the modulation amplitude, the photothermal phase can provide a complementary, sensitive probe of thermally-induced changes in the local medium properties. As proof of principle, we study a widely used, technologically important polymer resist -- polydimethylsiloxane (PDMS). In addition we show how, with the help of simulations, it is possible to extract from phase/amplitude data the temperature-dependent properties of the photoannealed medium.