⁸⁷Rubidium Bose-Einstein condensates : machine construction and quantum Zeno experiments

Abstract

This thesis details construction of a new apparatus for the production of 87Rb Bose-Einstein condensates and a subsequent quantum Zeno effect experiment. An experimental apparatus for producing large Bose-Einstein condensates of 87Rb is described in detail. A high flux thermal atomic beam is decelerated by a Zeeman slower and is then captured and cooled in a magneto-optical trap. The atoms are then transfered into a cloverleaf style Ioffe-Pritchard magnetic trap and cooled to quantum degeneracy with radio frequency induced forced evaporation. Condensates containing up to 20 million atoms can be produced every few minutes. The quantum Zeno effect is the suppression of transitions between quantum states by frequent measurement. Oscillation between two ground hyperfine states of a magnetically trapped 87Rb Bose-Einstein condensate, externally driven at a transition rate WR, was substantially suppressed by destructively measuring one of the levels with resonant optical scattering. While an ideal continuous measurement will stop the transition, any real measurement method will occur at a finite rate. The suppression of the transition rate in the two level system was quantified for pulsed measurements with a time between pulses t and weak continuous measurements with a scattering rate y. We observe that the weak continuous measurements exhibit the same suppression in the transition rate as the pulsed measurements when ySt = 3.60(0.43). This is in agreement with the previously predicted value of 4. Increasing the measurement frequency suppressed the transition rate to 0.005WR.