Laser Cooling
A technique using photon momentum from red-detuned laser beams to slow down moving gas atoms, cooling them to microkelvin temperatures.
Governing formula
F_force = ℏ k γ (I / I_sat) / (1 + 4 (Δ ± k v)² / γ²)
SI unit
μK or nK (Temperature)
In depth
Doppler cooling shines laser light tuned slightly below atomic resonance frequency. Atoms moving toward the laser absorb photons due to Doppler shift, receiving momentum kicks opposite to their velocity that slow them down.
Examples in the real world
Cooling neutral Rubidium atoms down to nanokelvin temperatures to create Bose-Einstein Condensates.