Magnetic monopoles are hypothetical objects that act like the isolated north or south pole of a magnet. Ordinarily when you break a magnet in half, you end up with two smaller magnets, but some theories predict independent existence for monopoles — though they obviously must be rare in nature, because we haven’t seen one yet.

When detectors fail, sometimes ingenuity can provide another way. As Richard Feynman realized, quantum systems can be used to simulate each other if the structure of their quantum states is the same. A group of researchers used a Bose-Einstein condensate — a collection of very cold atoms that behave like a single quantum system — to emulate the behavior of a magnetic monopole.

Thus, in lieu of hunting for particles that are monopolar, M. W. Ray, E. Ruokokoski, S. Kandel, M. Möttönen, and D. S. Hall emulated the behavior of a north magnetic charge using ultracold atoms. The result was behavior described as a Dirac magnetic monopole, something never before seen. This experiment relied on the quantum character of monopoles and might provide hope that isolated magnetic charges could exist in nature.

Quantum simulations work like simulations run on an analog computer: researchers construct electric circuits that obey the same basic mathematical equations as a more complicated physical phenomenon, which allows them to emulate the complicated system without trying to solve the (possibly unsolvable) equations that describe it. A quantum simulation lets physicists substitute a controllable physical system for one that might be too challenging to ever construct in the lab. [Read more….]

Emulating magnetic monopoles in Bose-Einstein condensates


Successful techniques exist for bringing atoms down to really cold temperatures, into the regimes where the most exotic collective quantum phenomena appear. However, those same techniques don’t work for polyatomic molecules—those consisting of three or more atoms. This is a bit frustrating for physicists, since molecules have the potential to exhibit some truly wild quantum effects: parity violation (processes that depend on which direction they occur), quantum chemical effects, and—hopefully—new phenomena which we don’t expect. A new experiment has succeeded in using three different types of light in tandem to bully molecules down to cold temperatures, a process known as Sisyphus cooling.

For this reason, the researchers in the present study turned to a more elaborate technique, where multiple processes were utilized in succession to cool the molecules. The experimenters sent a stream of molecules into a trap made from standing microwaves crossed with an infrared laser beam. The trap itself consisted of a sort of radio antenna; by varying the frequency of the radio waves, the researchers could extract energy from the molecules rapidly.

The combination of the excitation with a laser and the jostling by radio waves boosted the energy state of the molecules slightly, but they lost even more energy when coming down, resulting in ever colder temperatures. This virtual harassment to produce ultracold temperatures gives the process its name of Sisyphus cooling, referring to the Greek myth of a wicked king punished in Hades to repeat a single task forever. [Read more….]

Camus imagine it? Sisyphus cooling brings molecules to millikelvin temperatures