Spatio-spectral localized modal coupling for room-temperature quantum coherence protection.

This work aims to advance the room-temperature manipulation of photonic qubits and enhance coherence preservation in and for quantum applications via tailored spatio-spectral localized (SSL) systems. We focus on an innovative all-plasmonic SSL system consisting of a gold bowtie array on a gold substrate. This design produces a high-Q spectral-localized mode through the lattice array, emerging from the collective lattice response of localized surface plasmon resonance (LSPR), particularly the surface lattice resonance (SLR). The SSL system enables tunable modal coupling between the LSPR and SLR, allowing precise alignment with quantum emitters to form quasi-bound states across an energy range of 1.45-1.91 eV. This flexibility allows us to investigate how innovative configurations - such as three-body coupling symmetry and modal-coupling strength - affect coherence protection. These insights pave the way for optimizing SSL systems, setting the stage for significant advancements in nanophotonic qubit manipulation at ambient conditions and the future of photonic quantum systems.