State readout by coherent motion with few-photon seeding

The motion of a single trapped ion resonantly driven by pulsed radiation pressure is studied. We demonstrated that the driven ion quickly builds up coherent oscillations above the thermal motion, after scattering of order only one hundred photons. The motion is analyzed by Doppler velocimetry with subsequent motional amplification. Since the radiation pressure is state-dependent, this motional seeding technique provides a simple method to read out spectroscopy results from a single non-fluorescing ion with a partially closed cycling transition.