  We implement an all electrical controller for 3D feedback cooling of an
optically levitated nanoparticle capable of reaching sub-Kelvin temperatures
for the center of mass motion. The controller is based on an optimal policy
where state estimation is made by delayed position measurements. The method
offers a simplified path for pre-cooling and decoupling the transverse degrees
of freedom of the nanoparticle. Numerical simulations show that in an improved
setup with quantum limited detection, 3D ground state cooling and all
electrical quantum control can be achieved.
