Bose-Einstein condensates (BECs) are cool in more ways than one. Predicted to exist in 1924 by Satyendra Bose (and that other guy), this new form of matter unlike solids, liquids or gases was actually created in 1995 by Eric Cornell and Carl Wieman, for which they won the 2001 Nobel Prize in physics. To vastly oversimplify, if you get a sample of gas atoms really, really cold they will lose their identity as individual gas atoms and sort of blob together into one gigantic “superatom” – a BEC. Heating a BEC up is kind of like melting a solid block of ice into a pool of liquid; a BEC “melts” back into the individual gas atoms from which it was formed. It takes a really special “laser freezer” to make a BEC – one that uses laser beams to keep the gas sample from touching anything else which would only warm it up, and also to cause “cooling” so the BEC can form.
People have known for thousands of years that they can easily stick their thumb into a cup of water but not at all into a block of ice. Even though you’ve seen this yourself and know it to be true, doesn’t that strike you as ODD? Almost magical? In the less-than-a-decade time we’ve had BECs to play with, we’ve learned some similar rules-of-thumb that seem like magic, too, but aren’t – they’re just quantum mechanics. Now a recent report from the Max Planck Institute for Quantum Optics (MPQ) show just how strange some of these new BEC rules-of-thumb can be. They developed a “laser freezer” with lots of laser beams that effectively divided up a test volume into the equivalent of a 3-D egg carton. Load the “egg crate” up with 3600 atoms of rubidium gas atoms, tweak the laser beams a little, and presto-chango! At the flip of a switch they can go from 3600 laser-beam-isolated atoms into a single BEC blob and back again. Nice trick, but nothing compared to their next performance. Another tweak of the old laser beams, and the 3600 atoms become split between 7200 laser-delineated volumes – each atom is in two places at one time! Wow! Applause!
For their next performance, these magicians, er, scientists, are trying to rig up the lasers so two different “crates” of 3600 atoms can touch each other atom-to-atom. This is expected to create a controlled array of 3600 quantum-mechanically “entangled” atoms (another topic for another day) that could have amazing computing powers as the core of a quantum computer. Such a quantum computer would be better than a magic tophat with a million billion trillion rabbits, er, calculations per second, in it. Stay tuned.
And if anybody that REALLY understands BECs is reading this instead of a charlatan like me, answer me a question. You take a thousand radioactive atoms and form a BEC for a duration of a half-life, then warm it back up. What do you get?