Synopsis: Making monopoles

Monopoles with a single magnetic charge could be simulated in Bose-Einstein condensates
Synopsis figure
Illustration: Courtesy of V. Pietilä and M. Möttönen

Magnets found in nature always come with a north pole and a south pole, but in the 1930s Dirac considered the possibility of monopoles with magnetic charge much like positive or negative electric charge. Discovery of such monopoles would have implications for cosmology and particle physics, to say nothing of fundamental quantum mechanics, but experimental searches in the 1970s and 1980s have proved fruitless. Physical analogies to monopoles have been found or predicted in several systems, however, including liquid crystals, quantum Hall devices, and superfluid helium, but nothing exactly like the Dirac monopole has yet been observed. In a paper in Physical Review Letters, Ville Pietilä and Mikko Möttönen at the Helsinki University of Technology, Finland, and the University of New South Wales, Australia, now calculate that in principle Dirac monopoles could be observed in the spin structure of a Bose-Einstein condensate.

At extremely low temperatures, alkali atoms condense to a single quantum state—the Bose-Einstein condensate—but still exhibit a spin that can be manipulated (called a spinor BEC). The authors propose that with the right kind of external magnetic fields, the ultracold atoms in the BEC, each with its own spin, could be arranged in a spherically nontrivial formation. Other external field configurations could be used to imprint different spin textures on the BEC, which are defects in the topology of the spin arrangement such as points or lines.

In this way, the BEC could be engineered to have a spin vorticity equivalent to the way magnetic field lines emanate from a Dirac monopole. If this theoretical proposal can be experimentally realized, researchers would have a testbench to examine how monopoles form, how long they live, and whether Dirac monopoles could be found in the wild. – David Voss


Features

More Features »

Announcements

More Announcements »

Subject Areas

Atomic and Molecular PhysicsParticles and Fields

Previous Synopsis

Next Synopsis

Related Articles

Viewpoint: Inducing Transparency with a Magnetic Field
Optics

Viewpoint: Inducing Transparency with a Magnetic Field

A magnetic field applied to an atomic sample in an optical cavity generates optical transparency that could be used to enhance the frequency stability of lasers. Read More »

Viewpoint: Getting to the Bottom of an Antineutrino Anomaly
Particles and Fields

Viewpoint: Getting to the Bottom of an Antineutrino Anomaly

The Daya Bay Collaboration reports that sterile neutrinos probably aren’t behind a puzzling deficit in detected antineutrinos at nuclear reactors. Read More »

Synopsis: Solving Many-Body Problems with a Quantum Microscope
Quantum Physics

Synopsis: Solving Many-Body Problems with a Quantum Microscope

A microscope that images the momenta of atoms in a Bose-Einstein condensate could solve quantum many-body problems. Read More »

More Articles