A charged wire interferometer for atoms

Atom interferometers have been successfully applied for precision measurements and the realization of basic gedanken experiments [1]. They consist of three or more atom optical elements to split, redirect, and recombine the motional state of the atoms. These elements are implemented either by freestanding microstructures or by light fields. For high precision applications, such as gyroscopes [2–5], a large throughput of the initial atomic flux is advantageous [6]. In order to efficiently use all atoms in an uncollimated thermal atomic beam, the ideal atom interferometer should produce equally spaced fringes for a wide range of transverse and longitudinal velocities. So called “white light” interferometers solve the problem for different longitudinal velocities by the recombination of only two velocity independent transverse momentum states at the output of the interferometer. Examples for this are the three-grating interferometer [7], operating with a transversely collimated beam, and the Raman interferometer [8]. Operation using a transversely uncollimated atomic beam can also be realized by the Raman interferometer and, for interferometers that do not require light, by the Talbot-Lau interferometer [9]. The latter, in contrast to Ref. [7], operates with three gratings in the Fresnel regime of matter wave diffraction. Since, in this case, many different momentum components build up the interference pattern, the typical length scale of the setup, the Talbot length, depends on the atomic velocity. The Talbot-Lau interferometer is, therefore, chromatic. In this work, we study a charged wire as the central element in an atom interferometer that requires only microstructures, operates in the Fresnel regime, and accepts, therefore, an uncollimated beam of atoms. At the same time, it has essentially white light character over the range of the atomic velocities in our thermal atomic beam. This makes future extensions of our approach based on microstructures potentially as powerful as, for example, the Raman interferometer gyroscope [5]. The attractive interaction between the induced dipole and the charged wire redirects the atomic trajectories to form a simple interferometer with two spatially separated paths. It can, therefore, also be used to measure the recently proposed topological phase shifts for moving electric dipoles [10–13].