“New short-distance forces are a frequent prediction of theories beyond the standard model, and the search for these new forces is a promising channel for discovering new physics,” says Jay Wacker of the SLAC National Accelerator Laboratory in California. The question is how to find them.

Wacker makes the argument that atom interferometry has matured to the point where it should be the instrument of choice in the search for these new forces on scales ranging from 100 micrometers to 1 kilometer.

The basic idea is to send two entangled atoms around separate arms of an interferometer and to look at the interference pattern they create. Placing a test mass near one of the arms should cause the atoms in that arm to deviate in a way that is easily calculated using Newton’s law of gravity. This path deviation should be easy to spot in a change in the interference pattern.

If you then subtract the Newtonian effects of the test mass from the data, whatever is left must be a new force.

Wacker says that state-of-the-art atom interferometry could already improve on the existing limits for new forces by an order of magnitude and that advances expected in the near future could improve on that by another order of magnitude.

So what might these kinds of experiments find? Various theories of supersymmetry predict the existence of extra dimensions that could exert forces on these kinds of scales, while others predict that gravity may shut off entirely or that new types of particles such as Peccei-Quinn axioms can mediate forces on these scales.

That’s an exciting mix of new physics to look forward to. And if Wacker is anything to go by, we could be seeing some of it sooner rather than later.

Ref: arxiv.org/abs/0908.2447: Using Atom Interferometery to Search for New Forces