Cavity-Modified Local Density of States as a Noise-Resilient Stabilizer for Asymmetric Ultrafast Kinetic Channels

We study a bimodal chiral optical cavity as a dissipative ratchet for ultrafast charge extraction in a TIPS-pentacene-inspired three-state singlet-fission model (|TT⟩ → |DMo⟩ → |C⟩). A directional complex light-matter phase φ applied exclusively to the right-circular cavity mode, combined with asymmetric mirror loss rates (κ_L ≫ κ_R), breaks time-reversal symmetry and creates a one-way dissipative valve. The cavity-modified local density of states (LDOS) ratchet delivers a ~1% absolute yield enhancement at φ = π/2 (90.9% → 91.9%) and remains effective when pure dephasing overdamps coherent polariton oscillations, confirming that the directional bias arises from LDOS reshaping rather than coherent dynamics. Quantum trajectory Monte Carlo unraveling (5000 trajectories) confirms the master-equation yield to 0.15% and resolves the kinetic hierarchy: forward-channel jumps dominate 0–80 fs, followed by a sharp κ_L-mediated extraction burst with back-leakage strongly suppressed. The model maps directly onto helicoid-on-mirror nanoparticle-on-mirror chiral plasmonic picocavities with g ≈ 50–200 meV, with clear experimental signatures in circular dichroism, photocurrent versus twist angle, and ultrafast time-resolved spectroscopy.