AUSTIN, Texas—Physicists at The University of Texas atAustin have discovered a new technique for cooling atoms and moleculesthat will allow them to study quantum physics more effectively with agreater variety of particles.
The researchers have found a way touse lasers to form walls that allow atoms and molecules to pass throughin one direction, but do not allow them to return.
The technique could lead to advances in atomic clocks, which are used to standardize time worldwide.
Dr.Mark Raizen of the Center for Nonlinear Dynamics and his colleaguesdescribe the one-way wall technique in Physical Review Letters andEurophysics Letters published earlier this year.
Raizen and hiscolleagues show that atoms and molecules can first be trapped in a boxwhose walls are built of laser light. The box can then be separatedwith an optical wall constructed of two lasers. These two lasers workin concert to allow atoms and molecules to pass through to one side ofthe box but block them from getting back to the other side. The boxthen has two distinct spaces, one filled with particles and one void ofparticles.
Raizen’s one-way wall extends the capabilities oflaser and evaporative cooling, which have been limited to cooling asmall number of atoms in the periodic table. The new method isapplicable to a greater diversity of atoms and molecules and can expandthe capability of researchers to test laws of quantum physics atextremely low temperatures.
“In nature, the cell wall is the classic example where atoms and molecules move through a one-way barrier,” Raizen said.
Cellsregulate the flow of ions through one-way channels in order to createosmotic pressure. Raizen and his colleagues illustrate it is possibleto create a manmade barrier to such atomic movement.
“The beauty of the one-way atomic wall,” Raizen said, “is that there is almost no increase in kinetic energy.”
Withno increase in kinetic energy comes no increase in heat. By expandingand contracting the space that holds the trapped atoms and molecules,the temperature of this space, which Raizen calls a “quantumrefrigerator,” can be lowered until it reaches very close to AbsoluteZero.
It’s at these ultra cold temperatures, -459 degrees Fahrenheit, that quantum physicists can manipulate atoms and molecules.
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