Jaynes-Cummings Model — Collapse & Revival

Two-level atom in a cavity; coherent field state |α⟩; ⟨σ_z(t)⟩ shows collapse then revival

Mean photons |α|²: 8

Coupling g: 1.0

Time span: 80

Detuning Δ: 0.0

⟨σ_z(t)⟩ = Σ_n P_n cos(2Ω_n t) where Ω_n = √(n+1)g (resonance) or √((n+1)g²+Δ²/4). Collapse time ∝ 1/(g), revival time ∝ 2π|α|/g. Atom starts in excited state, field in coherent state.