SQUID-Like BEC...

Physics World: Bose-Einstein Condensate torus cut by a laser

Physicists in the US have developed an analogue of a superconducting quantum interference device (SQUID) that replaces the superconductor with a Bose–Einstein condensate and measures rotation rather than magnetic flux. They hope that the research will lead to the development of new, ultra-sensitive gyroscopes.

The SQUID is a well-established and extremely sensitive device for measuring magnetic fields that has found a range of commercial applications. At its heart is a loop of superconductor broken by one or two Josephson junctions. These are thin barriers of non-superconducting material that superconducting pairs of electrons are able to tunnel across. SQUIDs rely on the fact that superconducting electrons are all represented by the same wavefunction, which extends around the loop and includes the junctions. This means that the current that flows around the loop – and therefore the magnetic flux through the loop – is quantized at discrete values. If the magnetic flux in the loop increases or decreases, there is an oscillation in the voltage across the Josephson junctions every time the magnetic flux changes by one quanta. These quanta are very small and therefore an extremely small change in magnetic flux can be measured by counting the voltage oscillations.

Physics World: Physicists create SQUID-like Bose–Einstein condensate