A weird theoretical cousin of the Higgs boson, one that inspired the decades-long hunt for the elusive particle, has been properly observed for the first time. The discovery bookends one of the most exciting eras in modern physics.

The Higgs field, which gives rise to its namesake boson, is credited with giving other particles mass by slowing their movement through the vacuum of space. First proposed in the 1960s, the particle finally appeared at the Large Hadron Collider at CERN near Geneva, Switzerland, in 2012, and some of the theorists behind it received the 2013 Nobel prize in physics.

But the idea was actually borrowed from the behaviour of photons in superconductors, metals that, when cooled to very low temperatures, allow electrons to move without resistance.

Near zero degrees kelvin, vibrations are set up in the superconducting material that slow down pairs of photons travelling through, making light act as though it has a mass.


This effect is closely linked to the idea of the Higgs – “the mother of it actually,” says Raymond Volkas at the University of Melbourne in Australia.

Those vibrations are the mathematical equivalent of Higgs particles, says Ryo Shimano at the University of Tokyo, who led the team that made the new discovery. The superconductor version explains the virtual mass of light in a superconductor, while the particle physics Higgs field explains the mass of W and Z bosons in the vacuum.

Double trouble

Physicists had expected the Higgs-like effect to appear in all superconductors because it is also responsible for their characteristic property – zero electrical resistance. But it had only been seen before by imposing a different kind of vibration on the material.

To find it in a superconductor in its normal state, Shimano and colleagues violently shook the superconductor with a very brief pulse of light. Shimano says it is similar to how particle physicists create the real Higgs boson with energetic particle collisions. They first created the superconducting Higgs last year, and have now studied its properties to show that, mathematically speaking, it behaves almost exactly like the particle physics Higgs.

Noting the similarities between the two systems could be useful in studying the real Higgs boson. “One can prepare various types of ‘vacuum’ in condensed matter systems, which are not able to be realized in particle physics experiments,” Shimano says. “One can really do the experiments in a table-top manner, which would definitely reveal new physics and hopefully provide some useful feedbacks to particle physics.”

Journal reference: Science, DOI: 10.1126/science.1254697