Coherent Control of Processes that Break the Dipole Blockade

The Rydberg excitation blockade has enabled impressive achievements in quantum information and simulation.  However, state-mixing processes may compromise the single-excitation behavior of the blockade.  When ultracold atoms are excited to Rydberg states near Förster resonance, a significant number of atoms can be found in dipole-coupled product states immediately after excitation.  Under certain experimental conditions, this is due to laser excitation of mixed three-atom states.   We use a rotary echo technique to demonstrate the coherence of the evolution of these three-atom states.  We find good agreement between our data and a theoretical model for laser excitation in a coupled three-atom basis¹.

¹ PRL 102, 013004 (2009)