Flux pinning "quantum locking"

[pandemonium]

Very cool variation to the Meissner effect going on here.

 

[William Gaatjes]

It sure is. I have to do some background reading and recollection when i find the time. Nice article. It makes the explanation so easy. :thumbsup:

From the article you posted a link to:

What you start with is an inert [i.e. chemically inactive] disc, in this case a crystal sapphire wafer. That wafer is then coated with a superconductor called yttrium barium copper oxide. When superconductors get very cold (like liquid nitrogen cold) they conduct electricity with no loss of energy, which normal conducting materials like copper can't do.

Superconductors hate magnetic fields (when cold enough), and normally would just repel the magnetic force and float in a wobbly fashion. But because the superconductor is so thin in this case, tiny imperfections allow some magnetic forces through. These little magnetic channels are called flux tubes [pictured here].

The flux tubes cause the magnetic field to be "locked" in all three dimensions, which is why the disk remains in whatever position it starts in, levitating around the magnets.

Those of you with backgrounds in materials science, ceramics engineering or graduate-level physics may recognize this phenomenon as something similar to the Meissner-Ochsenfeld effect, though strictly speaking what you're witnessing is not a result of the Meissner effect.

In the Meissner effect, the superconductor that is placed within the magnetic field deflects the field entirely (see the image pictured here), such that none of the field passes through the object itself.

But as Hanson points out, the thinness of the superconductive coating featured in the quantum locking video allows for the magnetic field to penetrate it (albeit in discrete quantities) wherever there exist defects in the superconductor's molecular structure. This penetration gives rise to the "flux tubes" (again, pictured alongside Hanson's explanation), which pass through the inert crystal sapphire wafer and "trap" it in midair. This trapping provides the typically wobbly "levitation" characteristic of the Meissner effect a stiffer quality.

As for your hoverboard: as Hanson points out in his explanation, superconductors only possess their field-banishing properties at extremely cold temperatures, making hovering skateboards more or less impossible at this point. But for what it's worth, there's currently no evidence that says room-temperature superconductors can't exist—we just haven't haven't discovered them yet.