JAYNES-CUMMINGS MODEL

Two-level atom in cavity QED — vacuum Rabi oscillations, collapse & revival

PARAMETERS

Jaynes-Cummings: H = ħg(a†σ⁻ + aσ⁺)

Atom inversion: W(t) = Σ Pₙ cos(2g√(n+1) t)

Collapse: dephasing due to photon-number spread.
Revival: quantum interference at t_rev ≈ 2π√n̄/g

Coherent state collapses and revives periodically — a purely quantum effect.