Doppler Cooling — Iris Labs

Atom Gas — Click to start/stop cooling

T = 300 μK | v_rms = -- m/s

Laser detuning Δ: −Γ Laser intensity I/I_sat: 0.5

f_absorbed = f_laser · (1 + v/c) [Doppler shift]
Γ_scatter = (Γ/2) · I/I_sat / [1 + I/I_sat + (2Δ/Γ)²]
k_B T_Doppler = ħΓ/2 ≈ 240 μK (Na)

Velocity Distribution

The Maxwell-Boltzmann distribution narrows as atoms cool. The Doppler limit (T_D = ħΓ/2k_B) is set by spontaneous emission randomness — each photon kick adds √2 · ħk of momentum noise.

Sisyphus cooling (below T_D): atoms climb potential hills of the standing wave, lose energy, optically pump to valley — like Sisyphus pushing a boulder uphill forever.