An atom interferometer is a ubiquitous tool for measuring fundamental constants and inertial sensing. While it has been extremely useful in measuring inertial rotations, the fine-structure constant, gravity gradients, and local gravity, the measurement process lacks the ability to probe continuously due to its single-shot nature. In this work, we experimentally demonstrate the diffraction of an atom laser in the Raman-Nath regime, a key step towards the development of an atom-laser-based interferometer. The diffraction orders can be precisely controlled, and momenta up to $\ifmmode\pm\else\textpm\fi{}18\ensuremath{\hbar}k$ can be imparted to the atom laser. We form the ``atom laser'' by outcoupling a quasicontinuous beam of coherent atoms from a reservoir of
87Rb Bose-Einstein condensate lasting up to 400 ms. This atom laser then interacts with a grating formed by a standing wave of far-detuned laser light. By controlling the interaction time, the strength of diffraction into various orders can be controlled. Such diffraction would allow for the construction of an atom-interferometer to probe changes in physical environments continuously up to a few hundred milliseconds.
Atomic state manipulation by laser radiation requires a stringent control of the light phase noise for precise spectroscopy and quantum computation . In this work we describe a novel interferometer recently employed to estimate the phase noise induced by an optical frequency shifter based on serrodyne modulation for optical frequency standards (Barbiero et al., 2023). The interferometer is generated by an acousto-optic actuator working in the Raman-Nath regime. Using the heterodyne detection between the unshifted optical mode with the first higher order optical components , we are able to detect the differential phase between the two optical path arms with a reduction of the phase noise induced by the actuator. We provide a theoretical treatment for the actuator phase suppression and we estimate the detectable phase noise limit of this interferometer. Finally, we discuss the possible applications in the field of precision measurements.