A beautiful math emerges from the acrobatic flips of supercold atoms in a magnetic field, researchers report in the Jan. 8 Science.
Scientists detected an elusive, complex symmetry known as the E8 Lie group in resonating particles, a symmetry long analyzed on paper but never seen in a physical system. The work suggests that this numerical grace may be hidden in other physical systems and may provide a mathematical link between quantum processes in condensed matter and the physics of the cosmos.
“Finding a mathematically exotic symmetry in a regular material we can find on Earth — well, it is mathematically beautiful and very interesting,” comments Robert Konik of Brookhaven National Laboratory in Upton, N.Y. Symmetries helped theoretical physicists to predict the existence of certain particles before they were detected and to explain phenomena such as superconductivity. E8 in particular may help describe the unseen dimensions in string theory. But the emergent E8 symmetry in this system may be nothing more than a mathematical curiosity, researchers say.
The team of scientists from England and Berlin began with chains of the magnetic material cobalt niobate, a material whose electrons have a preferred direction of spin — either up or down. The researchers chilled the cobalt niobate to a cool 40 millikelvins (-273.1Ë Celsius) and then applied a magnetic field to the material. Without this external magnetic field, the spins of the electrons would all align in the same direction, like in an ordinary magnet. But an external magnetic field applied from the right direction introduces a tension, and at some point the electrons prefer to align with that magnetic field instead of with their neighbors. The electron spins are associated with particle-like states, known as quasiparticles, in the system.