For the first time ever, physicists have created and photographed synthetic magnetic monopoles by engineering an environment that mimics a monopole’s magnetic field in a cloud of rubidium atoms.
This is an artist’s impression of a synthetic magnetic monopole. Image credit: Heikka Valja.
In 1931, the English theoretical physicist Prof Paul Dirac predicted that the north and south poles of a magnet could exist independently and behave like electric charges.
Despite experimental searches since then no observation of a naturally-occurring magnetic monopole – a magnetic particle possessing only a single, isolated pole – has yet been confirmed.
In 2009, Finnish researchers published theoretical results demonstrating a method to create Dirac monopoles in a Bose–Einstein condensate, an extremely cold atomic gas tens of billionths of a degree warmer than absolute zero.
The idea involves using external magnetic fields to rotate the atomic spins. A Dirac monopole forms in the condensate as a result of the spin rotation.
This method was adopted by a team of physicists, led by Prof David Hall of Amherst College, in creating the synthetic magnetic monopole.
After resolving many technical challenges, Prof Hall and his colleagues were rewarded with photographs that confirmed the monopoles’ presence at the ends of tiny quantum whirlpools within the ultracold gas.
“The result proves experimentally that Dirac’s envisioned structures do exist in nature, even if the naturally occurring magnetic monopoles remain at large,” said Prof Hall, who is the senior author of a paper published in the journal Nature.
“The creation of synthetic electric and magnetic fields is a new and rapidly expanding branch of physics that may lead to the development and understanding of entirely new materials, such as higher-temperature superconductors for the lossless transmission of electricity.”
The discovery provides a stronger foundation for current searches for magnetic monopoles that have even involved the famous Large Hadron Collider at CERN.
“Our achievement opens up amazing avenues for quantum research. In the future, we want to get even a more complete correspondence with the natural magnetic monopole,” said co-author Dr Mikko Möttönen of Aalto University.
In the future, physicists will concentrate on more in-depth research into the structure of a synthetic magnetic monopole. They are also interested in the dynamics of monopoles and their interactions with other synthetic particles.
One interesting idea involves trying to create a monopole that is not bound to a whirlpool in the same way as is the Dirac monopole. This type of structure could possibly describe a natural magnetic monopole in even more detail.
______
M. W. Ray et al. 2014. Observation of Dirac monopoles in a synthetic magnetic field. Nature 505, pp. 657–660; doi: 10.1038/nature12954
