Ramsey interferometry with an atom laser

We present results on a free-space atom inter-ferometer operating on the first order magnetically insensitive |F = 1,MF = 0) -\F = 2, mF = 0) ground state transition of Bosecondensed ⁸⁷Rb atoms. A pulsed atom laser is output-coupled from a Bose-Einstein condensateand propagates through a sequence of two internal state beam splitters, realized via coherent Raman transitions between the two interfering states. We observe Ramsey fringes with a visibility close to 100% and determine the current and the potentially achievable interferometric phase sensitivity. This system is well suited to testing recent proposals for generating and detecting squeezed atomic states.