Quantum Zeno & Anti-Zeno Effect
Measurement rate controls whether decay is suppressed or enhanced
P_survive(T) = [cos²(Ωτ/2)]^(T/τ) — survival probability with N=T/τ measurements
Zeno: τ→0 ⟹ P→1 (frequent measurement freezes decay)
Anti-Zeno: ∃ optimal τ_AZ where P is minimized — measurements accelerate decay
Transition depends on spectral density J(ω) of the environment coupling (Kofman & Kurizki 2000)