Cooperative effects on Optical Forces- Dicke's Bullet

We investigate the cooperative effects on optical forces in a system of N two level atoms occupying a volume of dimensions to within $\lambda ^3$, where lambda is radiation wavelength and is driven by a coherent radiation field with a spatial profile like Laguerre-Gaussian beam or ideal Bessel beam.We show a dramatic enhancement on optical forces as well as the angular momentum imparted to the atom by a factor of $N ^2$.