Time to retire the old soldering iron? In the "atomtronic" circuits pictured on the right, it is atoms, not electrons, that flow. Such circuits could form the basis for ultra-sensitive gyroscopes.

Previously, atoms have been made to flow from one point to another. To get them to flow round and round in a circuit, Kevin Wright and colleagues at the National Institute of Standards and Technology in Gaithersburg, Maryland, chilled 100,000 sodium atoms until they became a Bose-Einstein condensate – a blob of floating atoms that behaves as a single, coherent quantum object.

The researchers used a complex array of lasers to trap and shape the blob into a torus. A further pair of lasers, one in a rotating configuration, gave the atoms just enough energy to circulate in unison around the ring, but not so much energy that the condensate decohered.

This "current" of atoms flowed for 40 seconds, four times longer than atoms in previous experiments.

Superfluid gyroscope

Flowing atoms act like frictionless "superfluids"", which are highly sensitive to rotation, so such atomtronic circuits might be used to build ultra-sensitive gyroscopes, says Wright.

His team also pinched off part of the torus with another laser, restricting the flow of atoms, but not stopping them entirely. In electrical circuits, the closest analogy to this is a Josephson junction, a gap over which current flows between two superconductors. These form the basis of superconducting quantum interference devices (SQUIDS), which are used to measure magnetic fields with high sensitivity.

Matthew Davis, a physicist at the University of Queensland in Brisbane, Australia, calls the new work "impressive" and agrees that it could eventually lead to "practical devices that are extremely sensitive for the detection of rotational or gravitational forces".

Source: NewScientist