Project Fair 4th Position

Laser Cooling & Atom Trapping


Brian Lim Youliang1, C.V. Satish Ramanath1

Wang Wei2

Mr. Koh Chong Mong3

Mr. Kannan Nagaswamy4


Laser cooling and atom trapping is a technology that is quickly gaining importance in the research community with a myriad of applications being created. Other innovative technologies have been developed, such as optical tweezers, which can grab and move microscopic objects around using light and the atomic fountain that can improve the accuracy of the atomic clock. Even a new science called Atom Optics has been spurned forth, involving the manipulation of atoms as waves, just as light can be manipulated now.


The investigation into this topic was initiated by the need for better scientific measurement, because slower atoms provide more time for study thus more accurate can be made. More precisely, it was to improve the accuracy of atomic spectroscopy, which is the study of the atomic structure by noting the frequencies (colours) of light that the atom absorbs and emits.


Cooling was to provide for slow moving atoms and trapping was to confine the motion of the atoms so that they remain in a region of study for an appreciable length of time. 2 important types of cooling schemes make use of light (laser light actually as it is more intense and consistent); matter was not used. Light is able to have a cooling effect, basically according to the first scheme, because it can exert a radiation pressure on matter. Scientists use this force such as to reduce the speeds of the atoms and hence causing a cooling process. The second mechanism causes the atoms to have their kinetic energy converting to the atomsí potential energy and then to light energy. It is possible to bring sodium atoms down to a temperature of 18nK (0.000 000 018K).


Optical and magnetic fields are used in the most popular trap, the Magneto-Optical Trap (MOT) to keep the atoms in place. The optical field is provided by the laser beams, the same ones used in cooling, intersecting perpendicularly and the magnetic field by a couple of solenoids.


With atoms brought to slow speeds, their wave characteristics begin to show and many quantum mechanical characteristics can be observed. Studying such atoms carefully can provide better insight into the strange world of quantum mechanics.


Brian Lim Youliang


To find out more about this interesting and exciting technology, please visit our website at _lim_youliang/


199S08, 299S05, 3 NJC Physics Department, 4HP Telementoring Scheme