Enhancing fiber atom interferometer by in-fiber laser cooling

We demonstrate an inertia sensitive atom interferometer optically guided inside a 22-cm-long negative curvature hollow-core photonic crystal fiber with an interferometer time of 20 ms. The result improves the previous fiber guided atom interferometer sensitivity by three orders of magnitude. The improvement arises from the realization of in-fiber Lambda-enhanced gray molasses and delta-kick cooling to cool atoms from 32 mu K to below 1 mu K in 4 ms. The in-fiber cooling overcomes the inevitable heating during the atom loading process and allows a shallow guiding optical potential to minimize decoherence. Our results permit bringing atoms close to source fields for sensing and could lead to compact inertial quantum sensors with a submillimeter resolution.