Quantum Embedded Superstates

Optical supercavity modes (superstates), i.e., hybrid emerging from the strong coupling of two an open cavity, can support ultranarrow lines in their scattering spectra associated with quasi bound states continuum (quasi-BIC). These are great interest for sensing applications as they enable compact systems unprecedented sensitivity. However, classical quasi-BIC sensors fundamentally limited by shot-noise limit, which may be overcome quantum sensors. Here, it is shown that a three-level system (e.g., atom, dot, superconducting qubit) tailored to analog superstates unboundedly narrow emission line. Remarkably, demonstrated such cavity plasmonic or dielectric nanoparticle, microcavity, microwave resonator) enables properties excellent statistical features. The results applied plethora platforms, circuits cold atoms and dots, opening exciting opportunities computing.