where ℏ ℏ = h 2 π π is the Planck constant and k B is the Boltzmann constant. The cold bath of temperature T c couples the ground (1-g) to an intermediate level (2-c) with energy gap E 2 − − E 1 = ℏ ℏ ω ω c . When levels 2-c and 1-g equilibrate then