Paul D. Lett

Quantum Encounters of the Cold Kind

Since the introduction of laser-cooling techniques for neutral atoms in the early 1980s, the study of collisional interactions between atoms and molecules has been extended to the regime of ultracold temperatures. With nanokelvin temperatures now attainable, our ability to probe the interactions, both experimentally and theoretically, has also progressed. Understanding of the subtle and often highly quantum-mechanical effects that are manifest at such low energies has advanced to the point where new precision measurements are matched by highly accurate theoretical calculations. Low-energy phenomena such as Bose–Einstein condensation and the photoassociation of atoms into bound molecules are now accurately described with no free parameters.

Delay of Quantum Correlations with an Atomic System

We use a four-wave mixing process in an atomic system to delay quantum correlations in twin beams. We have obtained a delay of 13 ns without a significant degradation of the intensity-difference squeezing.

All-Optical Bose-Einstein-Condensation of Sodium in a Crossed Dipole Trap

We report all-optical Bose-Einstein-Condensation of sodium in a far-detuned crossed-dipole-trap. Sub-doppler-cooled sodium atoms are loaded into a crossed-dipole-trap and subsequently condensed by optical evaporation which yields condensates of 150000 atoms distributed over several spin-states.

Quantum Interference in an Atom Molecule System

By driving photoassociation transitions with continuous-wave lasers, we stateselectively form excited-state molecules from ultra cold atoms. Using a second laser to drive transitions from the excited molecular state to another long-lived molecular state, we are able to observe an interference dip narrower than the natural linewidth of the excited molecular state. The linewidth of the dip is strongly effected by the temperature of the atoms. To reach smaller linewidths we have set up an all optical BEC.