Design of magnetic transport and trap for cold atom preparation on chip assembly

Abstract

In this thesis, we study the trapping patterns of rubidium atoms on atom chip components. To trap rubidium atoms using magnetic field generated from the atom chip, the atoms must be sufficiently cooled to be confined by a magnetic field. Initially, the cooled rubidium atoms are prepared using the optical magneto-optical trap (MOT), reaching temperatures in the hundreds of micro-Kelvins. Subsequently, we use optical molasses to achieve rubidium atoms with a temperature of approximately 30 micro-Kelvins. At this temperature, atoms can be trapped using a magnetic field with a gradient of 20 G/cm. Since the atom chip is placed outside a thick glass cell, the atoms need to be transported using a magnetic field for a distance of approximately 2 cm to bring the atoms close to the atom chip's surface (about 7 mm away). The magnetic field values are obtained from simulations using COMSOL Multiphysics. Afterward, the efficiency of the atom trapping by the magnetic field generated by the atom chip is tested by assuming that the distribution of atom at thermal equilibrium is Gaussian. The simulation results indicate that we can create a magnetic field that can be adjusted as desired and trap atoms at a distance of 7 millimeters for 100 milliseconds with an efficiency of 60%. In the experimental part, we aimed to achieve the preparation of cold atoms and to measure the temperature to reach the expected temperature of 30 micro-Kelvin under optical molasses state. Currently, the lowest temperature we can achieve for atoms in our trap is 82.5 micro-Kelvin.