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Two-dimensional (2D) heterostructures integrated into nanophotonic cavities have emerged as a promising approach towards novel photonic and opto-electronic devices. However, the thickness of the 2D heterostructure has a strong influence on the resonance frequency of the nanocavity. For a single cavity, the resonance frequency shifts approximately linearly with the thickness. Here, we propose to use the inherent non-linearity of the mode coupling to render the cavity mode insensitive to the thickness of the 2D heterostructure. Based on the coupled mode theory, we reveal that this goal can be achieved using either a homoatomic molecule with a filtered coupling or heteroatomic molecules. We perform numerical simulations to further demonstrate the robustness of the eigenfrequency in the proposed photonic molecules. Our results render nanophotonic structures insensitive to the thickness of 2D materials, thus owing appealing potential in energy- or detuning-sensitive applications such as cavity quantum electrodynamics.

Negatively charged boron vacancies (VB–) in hexagonal boron nitride (hBN) exhibit a broad emission spectrum due to strong electron–phonon coupling and Jahn–Teller mixing of electronic states. As such, the direct measurement of the zero-phonon line (ZPL) of VB–has remained elusive. Here, we measure the room-temperature ZPL wavelength to be 773 ± 2 nm by coupling the hBN layer to the high-Qnanobeam cavity. As the wavelength of cavity mode is tuned, we observe a pronounced intensity resonance, indicating the coupling to VB–. Our observations are consistent with the spatial redistribution of VB–emission. Spatially resolved measurements show a clear Purcell effect maximum at the midpoint of the nanobeam, in accord with the optical field distribution of the cavity mode. Our results are in good agreement with theoretical calculations, opening the way to using VB–as cavity spin–photon interfaces.

Diluted magnetic semiconductors (DMSs) have traditionally been employed to implement spin-based quantum computing and quantum information processing. However, their low Curie temperature is a major hurdle in their use in this field, which creates the necessity for wide bandgap DMSs operating at room temperature. In view of this, a single-electron transistor (SET) with a global back-gate was built using a wide bandgap ZnO nanobelt (NB). Clear Coulomb oscillations were observed at 4.2 K. The periodicity of the Coulomb diamonds indicates that the Coulomb oscillations arise from single quantum dots of uniform size, whereas quasi-periodic Coulomb diamonds correspond to the contribution of multi-dots present in the ZnO NB. By applying an AC signal to the global back-gate across a Coulomb peak with varying frequencies, single-electron pumping was observed; the increase in current was equal to the production of electron charge and frequency. The current accuracy of about 1% for both single- and double-electron pumping was achieved at a high frequency of 25 MHz. This accurate single-electron pumping makes the ZnO NB SET suitable for single-spin injection and detection, which has great potential for applications in quantum information technology.