has been demonstrated for instance with epitaxially grown quantum dots (QDs). In this case the QD can be pre-characterized and subsequently lifted off and positioned onto a resonator fabricated from conventional semiconductors such as silicon or silicon nitride. [13][14][15] This pick-and-place approach is laborious and requires sophisticated nanomanipulators within scanning electron microscope. It also suffers from limited precision of alignment and positioning of the source with respect to the resonator. In a complementary methodology, stamping techniques with polydimethylsiloxane (PDMS) rubber stamps or similar materials have also been demonstrated. [16,17] However, on balance, single-photon emission from the epitaxially grown QDs can only operate at cryogenic temperatures.A promising approach to the above issues is the use of emerging single-photon emitters in 2D materials. [18][19][20] Due to the 2D nature of the host, they can be transferred onto photonic structures via exfoliation and stamping, reproducibly and in ambient conditions. [21] Indeed, the first work on the coupling of quantum dots in 2D materials containing emitters-namely layered GaSe [22] or WSe 2 , [23,24] to photonic resonators have successfully been realized. However, due to the nature of the emission from these sources, their operation was limited to cryogenic temperatures. Quantum emitters in layered hBN are an ideal alternative. These sources are ultrabright and operate at room temperature. [25][26][27][28][29][30] Taking the advantage of these features, in this work we report the integration of room-temperature hBN quantum emitters with aluminum nitride (AlN) waveguides. We demonstrate transmission of nonclassical light through the waveguide, hence paving the way for future and more complex realizations including photon multiplexing and photonic circuitry on chip.

Fluorescent nanoparticles with optically robust luminescence are imperative to applications in imaging and labeling. Here we demonstrate that hexagonal boron nitride (hBN) nanoparticles can be reliably produced using a scalable cryogenic exfoliation technique with sizes below 10 nm. The particles exhibit bright fluorescence generated by color centers that act as atomic-size quantum emitters. We analyze their optical properties, including emission wavelength, photon-statistics, and photodynamics, and show that they are suitable for far-field super-resolution fluorescence nanoscopy. Our results provide a foundation for exploration of hBN nanoparticles as candidates for bioimaging, labeling, as well as biomarkers that are suitable for quantum sensing.

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Nanoscale optical thermometry is a promising non-contact route for measuring local temperature with both high sensitivity and spatial resolution. In this work, we present a deterministic optical thermometry technique based on quantum emitters in nanoscale hexagonal boron-nitride. We show that these nanothermometers exhibit better performance than that of homologous, all-optical nanothermometers both in sensitivity and range of working temperature. We demonstrate their effectiveness as nanothermometers by monitoring the local temperature at specific locations in a variety of custom-built micro-circuits. This work opens new avenues for nanoscale temperature measurements and heat flow studies in miniaturized, integrated devices.

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