A Magnetic Higgs Transition is Observed

This nuclear generator in Garching, Germany supplied the neutrons used to measure the experiment

Most of you are probably already aware that the Higgs particle, or something similar to it, was recently observed at the LHC. This also confirms the existence of what is called the Higgs field. Now, never before seen properties of this field have most likely been observed.

For clarification on this, quantum field theory emphasizes that all particles are really waves in a quantum field. So photons, particles of light, are really waves in the electromagnetic field. The same is true for particles of mass, like electrons, which are waves in an electron field.

The Higgs particle itself is just a wave in the Higgs field, and doesn’t play an important part in what that field typically does. This is similar to the fact that electricity doesn’t have to involve light, even though it involves the “photon” field.

The interaction between the Higgs field and other fields is thought to give certain particles their mass. Specifically, the weak nuclear force is a field that holds protons and neutrons together in the nucleus of the atom. Waves in this field become particles, much like photons.

Strangely, however, these particles have mass. This is because of an interaction between the weak nuclear field and the Higgs field. This interaction generates energy, which takes the form of mass. This fact also prevents the nuclear field from acting on large distances, so that it stays confined to the atom’s nucleaus.

The Higgs field can also interact with the photon field, giving rise to strange electromagnetic phenomena. And now, for the first time ever, Lieh-Jeng Chang and colleagues have observed some of these interactions.

(Update: After speaking with Dr Peter Woit, I was informed that what follows is not related to the fundamental Higgs field of quantum field theory. Instead, it uses a similar mechanism, referred to as the Higgs mechanism.)

Electrons behave like tiny magnets, oriented along the direction of their “spin.” In a class of materials called spin ice, cooled close to absolute zero, electrons arrange themselves into groups of four.

When stable, two Norths and two Souths will point toward the center of this group, cancelling each other out and producing no magnetic field.

But if this becomes disrupted, three Norths and one South (or visa versa) will point inward, producing an overall North or South spin. In other words, the group acts like a magnetic “monopole,” a North pole without a south pole (or visa versa).

The scientists observed this happening in quantum spin ice at 0.3 degrees Celsius above absolute zero.

Left: Neutron scattering graph of monopole behavior. Center: Simulation of this effect. Right: Conventional magnets just above transition temperature

Fluctuations in the magnetic field would cause these monopoles to disappear after a very short period of time.

However, when the ice was cooled down to 0.21 degrees above absolute zero, these monopoles began to move freely through the ice, acting as a wave. This could only be explained if magnetic fields were somehow inhibited in a way that would prevent them from interfering with the monopoles over long distances.

The best explanation we have at this point is the Higgs mechanism. The same mechanism that causes the weak nuclear force to stay confined to the nucleus is, evidently, confining magnetic fields within the quantum ice to short distances.

(Update: Again, it is important to stress that while the mechanism is the same, it does not involve the fundamental Higgs field.)

The result of this is that the material becomes a monopole “superconductor.” In the same way that electricity can move with zero resistance through an electric superconductor, magnetic monopoles can move freely through this material without any inhibitions.

Related: Higgs Discovery: The Power of Empty Space (Kindle Single)

Friday Roundup: Curiosity Lands on Mars, Sound Lens Built, Parrots Think Like 3-Year-Olds

Get Updates Here: