Infinite Square Well — Superposition & Quantum Sloshing

ψ = c₁ψ₁e−iE₁t/ħ + c₂ψ₂e−iE₂t/ħ: the probability density oscillates at frequency ΔE/h = 307 THz for a 1 nm well.
0.71
|ψ(x,t)|² — probability density
t = 0.00 fs  |  ⟨x⟩ = 0.500 L
⟨E⟩ = 0.940 eV  |  T_period = 3.67 fs
L = 1 nm  |  E₁ = 0.376 eV  |  E₂ = 1.504 eV  |  ΔE = 1.128 eV
⟨x⟩(t) = L/2 − 2c₁c₂·(16L/9π²)·cos(ΔEt/ħ)
Pure ψ₁: ⟨x⟩ = L/2 fixed (no sloshing)
⟨x⟩(t) — position expectation (last 2 periods)
Oscillation amplitude: 0.181 L  |  c₂ = 0.71