Jarzynski Equality

⟨e^{−βW}⟩ = e^{−βΔF} — free energy from non-equilibrium trajectories
1.00
1.0
50
100

Work Distribution P(W)

⟨W⟩
−kT ln⟨e^{−βW}⟩
ΔF (true)
|error|

Jarzynski Convergence vs Sample Size

The Jarzynski estimator is dominated by rare low-work trajectories. Direct average ⟨W⟩ ≥ ΔF (second law). Exponential average converges to ΔF.