Cavity-Enhanced Anisotropic Quantum Inertial Sensing via Semi-Dirac Polaritons and Hybrid Atomic–Solid-State Interferometry

We propose a hybrid quantum inertial sensor that achieves native directional acceleration sensitivity without mechanical gimbals. A thin ZrSiS film (exhibiting semi-Dirac dispersion) is integrated into a high-finesse optical microcavity or polaritonic mode. External acceleration induces a direction-dependent momentum shift Δk(θ) that imprints on the Berry-curvature-modified optical response, producing a measurable cavity resonance shift or reflected-light phase shift δφ. A cryogenically co-located Rb-87 Bose–Einstein condensate (BEC) interferometer operated at ∼100 nK provides an absolute isotropic reference phase φ_BEC. Differential processing (δφ_lattice − φ_BEC_calibrated) yields a vectorial inertial signal with built-in common-mode noise rejection. The architecture targets a sensitivity of 10⁻⁹–10⁻¹⁰ g/√Hz and a long-term drift floor below 10⁻¹⁰ g over one hour, while remaining compact and cryogenically integrated. By reading out the topological lattice optically rather than via DC conductivity, the design overcomes the fundamental signal-to-noise limitations of earlier electrical approaches. This work combines the intrinsic anisotropy of semi-Dirac fermions in ZrSiS with cavity QED techniques and atomic interferometry, opening a new path toward compact, directionally sensitive quantum inertial sensors for GNSS-denied navigation and precision geodesy.