  High-dimensional entangled states in orbital angular momentum (OAM) basis
offer several unique advantages for quantum information applications. However,
for the optimal performance of a given application, one requires a generation
technique for OAM entangled states that is completely postselection-free and
fully controllable. Nonetheless, despite several efforts in the past, no such
technique currently exists. In this article, we propose just such a technique
and experimentally demonstrate postselection-free generation of up to about
150-dimensional OAM entangled states. We report the generation accuracy, which
is a measure of the control, to be more than 98% for states with Gaussian and
triangular OAM Schmidt spectra and up to 90% for the maximally-entangled OAM
states, which have rectangular spectra.
