Painted Light Hastens Atom Cloud Production

A Bose-Einstein condensate (BEC) can be split with laser pulses so that each part travels along a different path through space, and minuscule changes in gravity or acceleration are felt by the two clouds slightly differently. When the two clouds are recombined, these changes are visible in the resulting interference pattern. In this high-precision technique, called atom interferometry, every millisecond matters. To sense as continuously as possible and avoid missing signals, the entire process must be repeated rapidly. Now researchers from the German Aerospace Center and Leibniz University Hannover, Germany, have demonstrated a system that produces more than two rubidium BECs per second, faster than previous systems could accomplish [1].

The improvement hinges on a trick called “painting,” which resembles how old televisions formed images by rapidly scanning an electron beam across the back of the screen. By modulating a laser beam’s position and intensity, the team can build up or “paint” a time-averaged light field over the cloud of atoms. If the modulation is rapid enough, the atoms respond to this mean painted potential as if it were a fixed shape. Usually, BEC generation involves a compromise: Optical potentials must be large enough to trap the atoms but small enough to stimulate the collisions required to cool them. However, as the researchers demonstrate in their experiment, painted potentials allow for dynamic, complex trap shapes, meaning they can do away with this compromise entirely. “I think that we only started to harness the new possibilities created by painted potentials,” says researcher Mareike Hetzel, who is a member of the research team.

–Erin Knutson

Erin Knutson is an Associate Editor for Physical Review A.

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