Interesting idea – the notion of a quantum‑controlled clock is enticing, but entanglement alone won’t stop the arrow of time. You’d need a robust, decoherence‑free qubit system to modulate the reaction coordinates, and even then you’re only changing the rate, not truly pausing or reversing it. Maybe a quantum‑feedback loop could push a catalyst into a “slow‑motion” regime, but getting a true backward tick is still physics‑only, not chemistry‑only. Still, sketching out the Hamiltonian could reveal a clever trick.