Quantum Levitation And The Superconductor

by Tammy Plotner on October 22, 2011

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Superconductivity and magnetic fields are like oil and water… they don’t mix. When it can, the superconductor will push out any magnetic fields from the interior in a process called the Meissner effect. It happens when a sample is cooled below its superconducting transition temperature, where it then cancels out its magnetic flux. What’s next? A superconductor. Now the fun really begins…

Even though scientists will claim otherwise, magnetism isn’t greatly understood. Because of electromagnetic induction (where an electric current is created when a conductor is moved through a magnetic field), a perfect conductor won’t change the magnetic flux when it cruises through at zero resistance. However, when cooled to the superconductor state the magnetic flux is expelled. Now we have perfect diamagnetism – where the interior magnetic field nears zero. At this point, if an external magnetic field is introduced, it will create an opposing magnetic field. This locks the two in place!

In the above video, a sample of yttrium barium copper oxide was cooled with liquid nitrogen to bring out its superconductive properties. The experiment shows it repelling the magnets which are loaded into the handheld unit. What’s unusual is that the sample can be angled, yet still held in place by the magnetic field. But keep on watching, because they’ve even created a “track” where the superconductor can be set into motion to either hover above – or below – the magnetic sensors.

While it might seem like just another science fair exhibit, think of the applications! You can almost envision mass transit gliding along carrying passengers inside a high temperature superconductor sourced vehicle… Or a warehouse where tow motors have become obsolete. Clean energy? Why not? Permanent magnets have been known to levitate. And when it comes to superconductors, electrons simply flow through in an orderly pattern without resistance. Why not “train” them?

Original News Source: Wired Science UK.

About 

Tammy is a professional astronomy author, President Emeritus of Warren Rupp Observatory and retired Astronomical League Executive Secretary. She’s received a vast number of astronomy achievement and observing awards, including the Great Lakes Astronomy Achievement Award, RG Wright Service Award and the first woman astronomer to achieve Comet Hunter's Gold Status.

email 000019 October 22, 2011 at 8:24 PM

two things come up in my thoughts; dwindling supplies of rare earth magnets, and the supply, dangers, and viability of using liquid nitrogen or hydrogen to keep superconductive trains running.

Lights in the Dark October 22, 2011 at 8:29 PM

When I shared this video on FB on Monday, it had maybe 20-30k views. Now it has 4.2 million! It’s awesome to see something so cool and sciencey go viral!

Anonymous October 22, 2011 at 9:03 PM

Could this be used for aircraft? Have a superconducting ring around a disc shaped craft and use the earth’s magnetic field to levitate it?

IVAN3MAN_AT_LARGE October 22, 2011 at 11:43 PM

Earth’s magnetic field is too weak to support such an aircraft by that means.

IVAN3MAN_AT_LARGE October 22, 2011 at 9:11 PM

Yo Tammy, at the first line, “magnetic field” should be plural.

Also, at the second paragraph, in the first line, “great” should be greatly.

Anonymous October 23, 2011 at 4:12 AM

YO! ‘Terminator of common decency’…. I SAW what you wrote earlier… SHAME!

IVAN3MAN_AT_LARGE October 23, 2011 at 10:49 AM

It was the beer talking…

Anonymous October 22, 2011 at 10:22 PM

Superconductors are of two types, which are defined by their Meissner effect. One type repels magnetic fields, which will levitate the superconducting object. A type I superconductor becomes a perfect diamagnetic material, which exhibits a magnetization in the opposite direction of an applied magnetic field. The Meissner effect creates a complete diamagnetic material so that no magnetic field lines are present in that material. I doubt this will suspend the object against gravity by putting it on bottom, for the magnetic fields in opposition will impose a force on the superconductor in the same direction as gravity.

There is what might be called an anti-Meissner effect where the superconducting material collimates magnetic flux lines into narrow tubes or vortex fluxes. If the magnetic field at large is not perfectly uniform it takes work to move the object through the magnetic field and so energetically it is favorable to remain in a region with B_in and B_out remains the same. This is the Landau-Ginsburg effect and is found in type II superconductors. I think that this is a case of a type II superconductor.

LC

IVAN3MAN_AT_LARGE October 23, 2011 at 1:29 AM

You’re right – as usual! See: Type-I superconductor; Type-II superconductor.

Torbjörn Larsson October 23, 2011 at 12:56 PM

Good analysis!

The presence of liquid nitrogen ice is the tip off that this is a high temperature superconductor (HTSC), hence a type-II. The movie is adding a bit gee whiz to catch the watcher.

- Type II superconductors fails gracefully because they will admit quantized flux tubes at higher fields and/or temperatures. Which is why they behave like this, as surmised.

- Using a HTSC makes for a convenient demonstration with liquid nitrogen. Now, the physics of them are not well understood. They behave like type II, but as mentioned in the video (IIRC) a thin film introduce defects such as grain boundaries that admit flux tubes specifically.

You also have to tune the flux tube effect to appear with the chosen field (and temperature), so again thin films helps with relatively weak permanent magnets.

But these HTSC are so far (AFAIK) made as thin films anyway. (O.o)

metamaterials October 24, 2011 at 1:10 AM

Do the magnetic fields in opposition impose a force on the superconductor in the same direction as gravity, that decays with distance as does Newton’s gravitational force G ? Is the vacuum of outer space considered a diamagnetic metamaterial similar to a superconductor superlens focusing trapping bending light in relativity gravitational lenses and black holes, because of the magnetic frame-dragging? Thanks I’m a big fan of your math, logical reasoning, and scientific factual knowledges and topics.

Anonymous October 24, 2011 at 2:30 AM

A magnetic field is due to a dipole, such as a bar magnet with a N and S pole. The field for such a configuration is about B ~ B_0(d/r)^3, for d the length of the dipole. This is in contrast to the dipole field that drops of as an inverse square. Now if you got a lot of these in a planar array the field then becomes fairly constant in space at least near these sources.

This has little to do with gravitational physics. There are four fundamental interactions: electromagnetism, the weak nuclear force, the strong nuclear force and gravitation. These interaction do in some way unify at higher energy or a more fundamental length. However, this happens in ways that are subtle or abstract.

LC

Anonymous October 23, 2011 at 4:24 AM

THAT is a cool video! VERY interesting effects!

Anonymous October 24, 2011 at 5:30 PM

Superconducting definitions can be found at: http://www.superconductors.org/terms.htm#dia
These definitions may help explain some of the concepts discussed in this blog.

The idea that metallic hydrogen may be a high temperature superconductor and that the extensive magnetic fields as found at Jupiter and Saturn may be evidence of this… is fascinating! What might confirmation imply about Earth’s mag. field? and/or the absence of such fields at Mars and Venus?

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