Comparative studies of the infrared (IR) and Raman spectra of the orthorhombic, tetragonal, and rhombohedral pressure-polymerized phases of ${\mathrm{C}}_{60}$ as well as the pressure-dimerized state have been performed at ambient conditions. The tentative assignment of the vibrational spectra of different phases has shown that they could be perfectly described by the molecular symmetry of the ${\mathrm{C}}_{60}$ polymers which are the structure-forming elements of crystalline polymerized phases. This allowed one to consider the IR and Raman spectra of the crystalline polymerized phases as characteristic of those of the appropriate one- and two-dimensional ${\mathrm{C}}_{60}$ polymers and to use them for molecular fractional analysis of polymerization products.

We demonstrate an all-optical thermometer based on an ensemble of silicon-vacancy centers (SiVs) in diamond by utilizing the sensitivity of the zero-phonon line wavelength to temperature, $\Delta \lambda /\Delta T=0.0124(2)$ nm K^–1 [6.8(1) GHz K^–1]. Using SiVs in bulk diamond, we achieve 70 mK precision at room temperature with a temperature uncertainty ${\sigma }_T=360\hspace{0.17em}\text{mK}/\sqrt{Hz}$ . Finally, we use SiVs in 200 nm nanodiamonds as local temperature probes with 521 mK/$\sqrt{Hz}$ uncertainty and achieve sub-Kelvin precision. These properties deviate by less than 1% between nanodiamonds, enabling calibration-free thermometry for sensing and control of complex nanoscale systems.

Monolithic integration of quantum emitters in nanoscale plasmonic circuitry requires low-loss plasmonic configurations capable of confining light well below the diffraction limit. We demonstrated on-chip remote excitation of nanodiamond-embedded single quantum emitters by plasmonic modes of dielectric ridges atop colloidal silver crystals. The nanodiamonds were produced to incorporate single germanium-vacancy (GeV) centres, providing bright, spectrally narrow and stable single-photon sources suitable for highly integrated circuits. Using electron-beam lithography with hydrogen silsesquioxane (HSQ) resist, dielectric-loaded surface plasmon polariton waveguides (DLSPPWs) were fabricated on single crystalline silver plates to contain those of deposited nanodiamonds that are found to feature appropriate single GeV centres. The low-loss plasmonic configuration enabled the 532-nm pump laser light to propagate on-chip in the DLSPPW and reach to an embedded nanodiamond where a single GeV centre was incorporated. The remote GeV emitter was thereby excited and coupled to spatially confined DLSPPW modes with an outstanding figure-of-merit of 180 due to a ~six-fold Purcell enhancement, ~56% coupling efficiency and ~33 μm transmission length, thereby opening new avenues for the implementation of nanoscale functional quantum devices.