Popular Mechanics has a new story up about an experiment first reported in Nature Physics that could fundamentally alter our current understanding of quantum physics — particularly with how quantum magnetic fluctuations disrupt superconductivity:
- Researchers just witnessed a superconductor behavior that defies our current understanding of physics.
- At a certain electron density, quantum fluctuations—the phenomena that make superconductors stop being superconductors—just… stop.
- The team behind this discovery has no idea why it happens, but looks forward to finding new physics to explain their discovery.
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Superconductivity is an inherently organized state of being, and fluctuations are the exact opposite. Bring on the fluctuations, you kill the superconductivity.
So, the team wanted to get a good look at these disruptive little buggers. In order to do so, they heated one side of their material until it was no longer behaving as a superconductor, but instead acting as an insulator. This causes the quantum fluctuations to produce quantum vortices—little whirlpools of
magnetic field that researchers can track to study fluctuations.
Throughout this entire experiment, the team had been maintaining a certain density of electrons flowing through the material. And after they established their gradient, they began to change those density levels. And here’s where it gets weird: at a certain density, the quantum fluctuations just… stopped. Poof.
And no one knows why. According to physics as we know it, that really shouldn’t have happened.
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If particle physicists are saying they have no idea what’s going on, things have gotten really complicated.
Meanwhile, Phys.org is reporting on a completely different study using uranium ditelluride (UTe2) as a superconductor (interestingly, the above Nature Physics study used tungsten ditelluride, WTe2) that has found a new class of superconductors resistant to disruption by high magnetic fields:
A team from HZDR, together with colleagues from CEA, the Tohoku University in Japan, and the Max Planck Institute for Chemical Physics of Solids, has now explained why a new material continues superconducting even in extremely high magnetic fields—a property that is missing in conventional superconductors. The finding has the potential to enable previously inconceivable technological applications. The study is published in Nature Communications.
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Superconductivity depends on two factors: The critical transition temperature and the critical magnetic field. If the temperature falls below the critical transition temperature, the resistance drops to zero and the material becomes superconducting. External magnetic fields also influence superconductivity. If these exceed a critical value, the effect collapses.
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In many conventional superconductors, the value of the transition temperature in Kelvin is roughly one to two times the value of the critical magnetic-field strength in tesla. In spin-triplet superconductors, this ratio is often much higher.
With their studies on the heavyweight UTe2, the researchers have now been able to raise the bar even higher: At a transition temperature of 1.6 kelvin (–271.55°C), the critical magnetic-field strength reaches 73 tesla, setting the ratio at 45—which is a record.
"Until now, heavy-fermion superconductors were of little interest for technical applications," explains the physicist. "They have a very low transition temperature and the effort required to cool them is comparatively high."
Nevertheless, their insensitivity to external magnetic fields could compensate for this shortcoming. This is because lossless current transport is mainly used today in superconducting magnets, for example in magnetic-resonance-imaging (MRI) scanners. However, the magnetic fields also influence the superconductor itself.
A material that can withstand very high magnetic fields and still conduct electricity without loss would represent a major step forward.
