(black) curve\], 0.01 \[dashed (red) curve\], and 0.1 \[dotted (blue) curve\]. $\Omega_\mathrm{c} = \Omega_\mathrm{r} = \Gamma/2$, $\delta_\mathrm{r} = \Gamma/2$, $\mu_\mathrm{B} B/\hbar = \Gamma/10$ ($B\approx 150\;\mu$T).](Fig04-g-m-states-dephasing){width=".85\columnwidth"}

![\[fig:powerbroadening\](Color online) Power broadening of the CPT resonances. Normalized (at $\delta_\mathrm{c}=\Gamma$) scattering rate spectra for different Rabi frequencies $\Omega_\mathrm{c} = \Omega_\mathrm{r}$: $0.1\Gamma$ \[solid (black) curve\], $0.3\Gamma$ \[dashed (red) curve\], and $\Gamma$ \[dotted (blue) curvee\]. $\gamma_{g,m}=0$, $\delta_\mathrm{r} = \Gamma/2$, $\mu_\mathrm{B} B/\hbar = \Gamma/10$ ($B\approx 150\;\mu$T).](Fig05-g-m-states-power){width=".85\columnwidth"}

As the cooling laser is red-detuned (typically $\delta_c\approx -\Gamma/2$), ground-metastable CPT resonances can be avoided by tuning the repumper slightly to the blue. If the repumper is modulated so that sidebands are created, care must be taken that no sideband is at Raman resonance either, as discussed in Sec. \[sec:polarizationmodulation\].

Metastable-level dark states \[sec:m-states\]
---------------------------------------------

The $|J_m=3/2\rangle \rightarrow |J_e=1/2\rangle$ repumper transition has dark states for all laser polarizations. In zero field, the scattering rate is practically independent of the repumper polarization \[see the solid (black) curve in Fig. \[fig:m-states\]\]. The optical pumping rate is $\Gamma_\mathrm{op} \approx 0.002 \Gamma$ and again Eq. (\[eq:Gamma\_op\]) gives a good estimate if we assume both fields to be linearly polarized so that we can use $C=C_{82}$ and $A_n=A_{86}$. This optical pumping rate is lower than the 