Atomic Fock State Preparation Using Rydberg Blockade

We use coherent excitation of 3-16 atom ensembles to demonstrate collective Rabi flopping mediated by Rydberg blockade. Using calibrated atom number measurements, we quantitatively confirm the expected root N Rabi frequency enhancement to within 4%. The resulting atom number distributions are consistent with an essentially perfect blockade. We then use collective Rabi pi pulses to produce N = 1, 2 atom number Fock states with fidelities of 62% and 48%, respectively. The N = 2 Fock state shows the collective Rabi frequency enhancement without corruption from atom number fluctuations.