An illustration of a "super-photon" created when physicists turned photons of light into a state of matter called a Bose-Einstein condensate.
Credit: Jan Klaers, University of Bonn
Physicists have come up with a new way to gaze longingly at some of the weirdest matter on Earth — the super-cold, super-calm gas called a Bose-Einstein condensate.
While scientists have been able to steal quick glimpses of the unusual gas, until now, simply snapping a picture of a Bose-Einstein condensate (BEC) often destroyed it by adding extra energy from light.
"The absorption of a single photon (the smallest packet of light) is enough to break one," lead study author Michael Hush, a physicist at the University of Nottingham, told LiveScience in an email interview. [Wacky Physics: The Coolest Little Particles in Nature]
By creating a new computer model, detailed today (Nov. 28) in the New Journal of Physics, the researchers have figured out a way to re-route this heat and keep BECs chilled even during long imaging sessions.
In principle, Hush said, the proposal "could allow a BEC to be imaged indefinitely, during which we will be able to directly look at the BEC and even control it using feedback."
"Being able to play around with a quantum object close to absolute zero right then and there is really exciting," he added.
Bose-Einstein condensates are atoms or other particles, such as photons, chilled to nearly absolute zero. The atoms are so languid they behave strangely, as a single, bloblike mass. The slow-moving nature of the particles means scientists can easily track and study atomic processes, such as atomic spins, by studying Bose-Einstein condensates. (They are named after Albert Einstein and the Indian theorist Satyendra Nath Bose.)
For more than a decade, physicists have peered at BECs with off-resonant photons, a type of laser imaging that tends scatter its energy off the super-chilled atoms instead of adding heat. But even this method will work for only a few tries, eventually destroying the condensate after a handful of images, Hush said.
To improve the imaging technique, Hush and his colleagues built a sophisticated computer model that simulates both off-resonant light and the weird behavior of Bose-Einstein condensates. The model revealed a never-before-seen heating effect caused by off-resonant imaging.
"The particular discovery presented in this paper was actually first thought to be a bug in our code," Hush said. "We thought this because simpler descriptions of BECs did not predict this heating."
Via their model, the researchers have devised a filter that removes the heating effect and feeds the extra energy back into the magnetic coils used to trap and chill the condensate, which will help keep the atoms cooled for longer periods. Now, when inquisitive viewers want to watch the atoms sit around, such picture-snapping would send more energy into the chill-inducing coils, actually making the condensate even colder.
The next step is trying out the filter in a real-world experiment.
"Once we had isolated what was causing the heating it was easy to come up with the feedback to correct it," Hush said. "Results like this are very promising, and make me hopeful that an experimental demonstration of feedback with a BEC may be possible in the near future."