Design of Zeeman Slower for Strontium atoMS

Abstract

The properties of a collection of atoms at extremely low temperatures (of the order of micro-kelvins or lesser) have been of theoretical interest for decades. It is only with the relatively recent advent of laser cooling has it been possible to create the conditions in which these properties can be studied. Laser cooling can decrease the temperature of atoms from around 900 K to a few microKelvins. The atoms experience a retarding force as they travel in a laser beam as they absorb and emit photons traveling in the opposite direction. There will be a Doppler shift in the velocity of the atoms due to this and the atoms move out of the range of the frequency of the light beam. One of the ways to correct for this is the design for a Zeeman Slower. The Zeeman Slower comprises a laser beam and a magnetic field in a solenoid. A Zeeman Slower for Strontium atoms has been designed as part of this project. The wavelength of the laser beam used is 461 nm. The transition used has a relatively large line-width of 32 MHz and using this can achieve high cooling rates. The Zeeman effect due to the magnetic field in the solenoid shifts the levels of the atoms. A spatially varying magnetic field profile can be designed to ensure that the atomic frequency remains in resonance with the frequency of the laser (i.e. the atoms will still be able to absorb the photons). The Slower can reduce the velocity of the atoms to a few tens of m/s.