Seeing From One To One Million Atoms

By Dr. Paul Griffin and Prof. Michael Chapman,
School of Physics, Georgia Institute of Technology,
and Dr. Colin Coates,
Andor Technology Plc

Electron multiplying CCD (EMCCD) scientific digital camera technology is used to image an extremely cold nano-climate, found in the laboratories of Professor Mike Chapman at the School of Physics, Georgia Institute of Technology. Chapman and his group focus on investigating the quantum behavior of atoms and photons, often at the single particle level. Cooling bosonic atoms to a very low temperature, beyond a critical temperature for the atom, causes them to condense into the lowest available quantum state, resulting in a new wavelike form. In this state, a cloud of atoms will form a macroscopic quantum state in which all the atoms share the same space and have phase coherence in their wavefunctions. Lasers are employed to confine and cool such atoms to nano-Kelvin temperatures (colder than the most remote regions of deep space, which are pervaded by cold microwave radiation — the afterglow of the Big Bang). The cooled atoms are used for studies including fundamental atom-photon interactions, atom optics and interferometry, and quantum computing (towards a future generation of supercomputers) and communication. Recent achievements of the Chapman Research Lab include the first all-optical Bose-Einstein Condensation (BEC), the first storage ring for neutral atoms, and cavity QED with optically transported ultracold atoms.

Laser Cooling
In 1997, the Nobel Prize was awarded for the discovery and advancement of laser cooling. Since then, laser cooling has become an important tool of atomic physics research. The techniques of optical molasses and magneto-optical trapping have allowed ultracold temperatures of µKs (millionths of a degree above absolute zero) to be reached with arguably much greater ease. In 2001 the Nobel Prize for Physics was presented for the long sought-after achievement of Bose-Einstein Condensation.

Laser cooling and trapping of atoms makes use of the mechanical effects of light on atoms. Atoms have specific resonance frequencies at which they interact strongly with light by absorbing photons which are subsequently re-emitted by spontaneous emission.

SOURCE: Andor Technology PLC