Quantum Levitation

A thin superconductor layer (~1µm thick) is coated on a sapphire wafer. Quantum physics tells us that the magnetic field penetrates into the superconductor in the form of discrete flux tubes. The superconductor strongly pins these tubes, causing it to float in midair. This effect is called ‘quantum levitation’.

The physics behind

We start 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 our 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.

Imagine a bullet fast train suspended in midair. The superconductor disc is suspended above/below two magnet rows and move frictionless along the rail. This demonstration is perfect for large audience such as in science museums and colleges.

The superconductivity group at Tel Aviv University

Lead by Prof. Guy Deutscher, a leading physicist in the field of superconductivity. We are studying the, yet unknown, mechanism of superconductivity in high temperature superconductors. We 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’.