Reconfigurable photonic crystal cavity arrays for multiplexed spin-photon interfaces in silicon

Color centers in silicon are a promising platform for realizing scalable quantum repeater nodes. The T center in silicon features long electron and nuclear spin coherence times and spin-dependent optical transitions. To build efficient spin-photon interfaces, we integrate T centers inside silicon photonic crystal cavities (PCC) which can achieve exceptional quality factors and small mode volumes, enhancing desired optical transitions. However, fabrication disorder limits the control precision of PCC resonances, requiring post-fabrication tuning strategies. In this work, we develop a novel approach in which a bus waveguide is evanescently coupled to an array of PCCs with precise frequency tunability. We condense nitrogen gas and use site-selective sublimation via resonant laser heating to tune a desired cavity. Using this method, we achieve programmable cavity resonance tuning with picometer-level precision for more than five cavities in parallel. This selective tuning allows us to align individual cavities in the array to desired T centers in the cavity mode volume. Leveraging this tunability, we will use an ensemble of inhomogeneously broadened T centers to develop efficient, frequency-multiplexed spin-photon interfaces in silicon photonics.