SQUID

Light can be confined inside a reflective medium—a stream of water, a thread of glass fiber. In fiber optics, the light moves, trapped in a glass strand via the mechanism of total internal reflection. Light “totally” bounces at the surfaces, back and forth, carrying information over vast distances. Perhaps the word total should be taken a little loosely, at least at the surface. Here, there is what’s called an evanescent field. Webster says “evanescent” means “tending to dissipate, like vapor.” In physics, an evanescent wave is a vanishing vibration, occurring at an interface.

PFC supported scientists at JQI have created the first controllable atomic circuit that functions analogously to a superconducting quantum interference device (SQUID) and allows operators to select a particular quantum state of the system at will.

By manipulating atoms in a superfluid ring thinner than a human hair the investigators were able for the first time to measure rotation-induced discrete quantized changes in the atoms’ state, thereby providing a proof-of-principle design for an “atomtronic” inertial sensor.