(PhysicsWorld) Physicist Holger Müller and colleagues at the University of California, Berkeley have loaded ultracold caesium atoms into the back of a van and driven them up a hill to demonstrate how quantum interference can be used to measure gravity outside the laboratory. When cooled to just above absolute zero, the atoms form the centrepiece of a portable gravimeter that might in future be used to measure how the Earth’s surface gradually rises to form mountains or to underpin the new physics-based definition of the kilogram.
As with other quantum gravimeters, this system uses an atom interferometer to measure the effect of gravity on clouds of atoms that are first trapped and cooled. But its creators claim that a new kind of magneto-optical trap allows the device to be smaller, simpler and more robust than rival designs.
Kai Bongs of University of Birmingham in the UK agrees that the new instrument’s simplicity is an important feature, arguing it could lead to quantum devices that are competitive in price with their classical counterparts (which cost about $100,000 each).