  We propose a scheme for generating two-dimensional turbulence in harmonically
trapped atomic condensates with the novelty of controlling the polarization
(net rotation) of the turbulence. Our scheme is based on an initial giant
(multicharged) vortex which induces a large-scale circular flow. Two thin
obstacles, created by blue-detuned laser beams, speed up the decay of the giant
vortex into many singly-quantized vortices of the same circulation; at the same
time, vortex-antivortex pairs are created by the decaying circular flow past
the obstacles. Rotation of the obstacles against the circular flow controls the
relative proportion of positive and negative vortices, from the limit of
strongly anisotropic turbulence (almost all vortices having the same sign) to
that of isotropic turbulence (equal number of vortices and antivortices). Using
the new scheme, we numerically study quantum turbulence and report on its decay
as a function of the polarization.
