Quantum reflection of Bose-Einstein Condensates

摘要: Recent developments in atom optics have brought Bose-Einstein condensates within 1 μm of solid surfaces where the atom-surface interactions can no longer be ignored. At longrange, interaction is described by weakly attractive Casimir-Polder potential which classically predicted to accelerate an incident toward surface it will interact strongly with internal modes surface, lose energy, and land a bound state surface. When very cold, on order few nanokelvin, however, acceleration atomic wavefunction so abrupt that may partially reflect from tail process known as quantum reflection. This work presents experimental evidence for reflection at normal incidence. Using atoms 23Na BEC, cooled nanokelvin recently demonstrated single-coil trap, controlled collisions were induced between silicon A maximum probability ∼ 12% was observed velocity mm/s. Atoms confined against low density exhibited enhanced lifetime due surprising aspect nano-structured are exhibit reduction reduced surfaces. pillared 1% bulk density, we observe enhancement 60%. velocities 2-25 mm/s, threshold dependence observed. below 2 saturate. We develop simple model predicts saturation result mean-field condensate. Thesis Supervisor: Wolfgang Ketterle Title: John D. MacAurthur Professor Physics David E. Pritchard Cecil Ida Green For parents my life,