"The longer the cavity and the narrower the beam waist, the better the beam quality of the laser emission, or |\langle x | s \rangle|^2\ = \sum_{j=1}^\N\,\Psi(r_j)^2\ +2 \sum_{j=1}^\N\,\Psi(r_j)\bigg(\sum_{m=j+1}^\N\,\Psi(r_m)cos(\Omega_m-\Omega_j)\bigg)"