Manipulation of cold atoms using an optical one-way barrier
This dissertation describes the development of an apparatus that can accommodate many atom-optics experiments, as well as an experimental demonstration of an optical one-way barrier for neutral atoms. The first part of this dissertation describes in detail the design and implementation of our apparatus. The experiment setup consists of optical systems, vacuum systems, imaging systems, and the related electronics. It is designed to be versatile enough for many cold-atom experiments, including the demonstration of an optical one-way barrier for neutral atoms, quantum measurement on the single-atom level, and the study of quantum chaos using Bose-Einstein condensates. The second part of this thesis presents the experimental study of an optical one-way barrier for neutral atoms. We demonstrated an asymmetric optical potential barrier for ultracold 87 Rb atoms. The atoms are confined in a far-detuned dipole trap consisting of a single focused Gaussian beam from a fiber laser. The optical one-way barrier consists of two focused laser beams oriented nearly normal to the dipole-trap axis and tuned near the 87 Rb D 2 transition. The first beam (main barrier beam) is tuned to work as either a potential well or barrier, depending on the state of the incident atoms. The second beam (repumping barrier beam) pumps the atoms to the barrier state on the reflecting side. We investigated the transmission and reflection dynamics of the atoms in the presence of the one-way barrier, and we verified its capability for increasing the phase-space density of a sample of neutral atoms using the one-way barrier. Our experiment is a realization of Maxwell's demon and has important implications for cooling atoms and molecules not susceptible to the standard laser-cooling techniques.