Friday, March 23, 2012

#QUANTUM: "Microcosm Mimics Observable Universe"

When cooled to ultra-cold temperatures, the quantum behaviors of microscopic systems, such as electrons encircling atoms, behave in a manner similar to macroscopic systems, such as planets encircling stars. Understandings derived from such experiments have implications in the study of crystalline semiconductors, superconducting wires, and next-generation magnetic materials.

Recent experiments reveal that the quantum behaviors of ultra-cold atoms may be able to simulate the evolution of the early universe, as well as the gravitational dynamics of black holes, fulfilling a prediction by Nobel laureate Richard Feynman who said that if scientists understand one quantum system well enough, they might be able to use it to simulate the operations of other systems that are too difficult to study directly.

The ultra-cold state that makes these similarities observable is called "quantum criticality," which is a state where atoms slow down to such as extent that the only properties they have left to exhibit are those they have in common with other phenomena. In this study, performed by scientists at the University of Chicago, atoms were slowed by temperatures below six nano-Kelvin--just six billionths of a degree above absolute zero (-459 degrees Fahrenheit) where atoms come to a complete stop. At temperatures this low, atoms behave in a manner strikingly similar to cosmological events that are nearly impossible to study.
According to professor Cheng Chin at the University of Chicago, such ultra-cold states produce conditions that will enable the study of the conditions that existed at the beginning of the universe--the Big Bang--as well as those that exist today inside the giant black holes at the center of most galaxies.

Together with doctoral candidate, Xibo Zhang, Chin has begun study of these exotic phase transition to quantum criticality. Others have obtained similar results under the influence of ultra-high pressures, magnetic fields, and other conditions, however the ease with which Zhang and Chin's experiments are conducted gives them a better chance to make their results applicable not only to cosmology, but to crystalline semiconductors, superconducting wires and next-generation magnetic materials.
Instead of refrigerators, the experimenters are using twin laser beams to cool a trap containing 20,000 cesium atoms inside a vacuum chamber, transforming them into what is called a superfluid with extremely high thermal conductivity, and almost zero viscosity. With their current experimental set-up, the researchers can hold the atoms in this state for up to seven seconds--eons compared to other experimental methods with exotic matter.

A charge-coupled device (CCD) is used to image the atoms in this state, essentially recording the shadows cast by the atoms after the intense laser beams pass through the vacuum chamber. By studying these images, the scientists hope to unlock the secrets of other quantum phenomena that are nearly impossible to observe, but which have been predicted by Nobel laureate Richard Fey to obey the same laws of physics.