Quantum levitation
Researchers at the Tel Aviv University have created a track around which a superconductor can float, thanks to the phenomenon of “quantum levitation“. Suspending a superconducting disc above or below a set of permanent magnets – the magnetic field is locked inside the superconductor ; a phenomenon called ‘Quantum Trapping’.
The superconductivity group at Tel Aviv University starts with a single crystal sapphire wafer and coat it with a thin (~1µm thick) ceramic material called yttrium barium copper oxide (YBa2Cu3O7-x ). The ceramic layer has no interesting magnetic or electrical properties at room temperature. However, when cooled below -185ºC (-301ºF) the material becomes a superconductor. It conducts electricity without resistance, with no energy loss. Zero.
Superconductivity and magnetic field do not like each other. When possible, the superconductor will expel all the magnetic field from inside. This is the Meissner effect. In Their case, since the superconductor is extremely thin, the magnetic field DOES penetrates. However, it does that in discrete quantities (this is quantum physics after all! ) called flux tubes.
Inside each magnetic flux tube superconductivity is locally destroyed. The superconductor will try to keep the magnetic tubes pinned in weak areas (e.g. grain boundaries). Any spatial movement of the superconductor will cause the flux tubes to move. In order to prevent that the superconductor remains “trapped” in midair.
[youtube]http://www.youtube.com/watch?v=VyOtIsnG71U&hd=1[/youtube]
The superconductivity group at Tel Aviv University:
Lead by Prof. Guy Deutscher, a leading physicist in the field of superconductivity. They are studying the, yet unknown, mechanism of superconductivity in high temperature superconductors. They are also dedicated to making the amazing physics of superconductors accessible and exciting for young and adults through the unique and counter-intuitive phenomena of ‘quantum trapping’ and ‘quantum levitation’.
