  We study spatially indirect excitons confined in a 10 $\mu$m wide
electrostatic trap of a GaAs double quantum well. We introduce a technique to
control the amplitude of the electric field interacting with the excitons
electric dipole, with nanosecond precision. Our approach relies on electronic
waveforms corrected for the distorsions occurring at highest frequencies so
that impedance matching is not necessary. Thus, we manipulate the confinement
of cold gases without inducing sizeable perturbations down to sub-Kelvin bath
temperatures.
