When one hears the terms “quantum” and “levitation” used in a sentence they conjure thoughts of theoretical physics and fantastical machines whose reality is not far from science fiction.  The video below was created by the Superconductivity Group at Tel Aviv University and demonstrates a levitation phenomenon similar to the Meissner effect (i.e., the complete expulsion of a magnetic field from a superconductor during its transition to the superconducting state).  In this case however, the superconductor is very thin and the magnetic field is able to penetrate the object – a sapphire crystal wafer coated with yttrium barium copper oxide.  The penetration of the magnetic field via “magnetic flux tubes” keeps the superconductor stable and “trapped” in midair.

The quantum levitation demonstrated in the experiment above is a bit different than the commercially-available magnetic levitation – or “maglev” – technology that us used in high-speed trains.  There are two types of maglev technology, both of which have their pros and cons:

• Electromagnetic suspension (EMS) – the train levitates above a steel rail while electromagnets (attached to the train) are pointed at the rail from below.  This uses a relatively low magnetic field and very high speeds (310 mph or 500 km/h) can be attained.  That said, the gap between the train and rail must be monitored constantly to avoid collision.
• Electrodynamic suspension (EDS) – both the train and the rail(s) exert magnetic forces on each other which provides a significant improvement in stability over EMS, although at slow speeds the reduced current in the magnets cannot support the weight of the train.  Therefore wheels and adequate physical track must also be included for the length of the run since the train could possibly need to slow down at any point.  Additionally, the EDS technology requires a relatively strong magnetic field and passengers with pacemakers, computers, credit cards, etc. cannot ride.

It is too early to tell what the commercial applications are for quantum levitation/trapping (Star Wars landspeeder anyone?) but the science certainly conjures many ideas that heretofore were the realm of science fiction alone.

[Thanks Stephen]

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