By applying a π/2- π- π/2 - interferometer sequence, a Mach-Zehnder configuration is realized in analogy to light interferometry but with switched roles of matter and light. The usage of three spatially separated interaction zones demands precise alignment of the relative mirror tilts. In our case, the alignment tolerance is in the µrad regime. As this alignment cannot be realized with optical means, we employ different interferometer topologies such as a Ramsey-Bordé configuration with higher alignment tolerance to realize the alignment. The alignment technique employing the atom interferometer itself lead to our latest publication.
Matter wave interference is observable in oscillating interferometer state population when scanning the relative laser phase for one of the three beam splitter pulses (see Fig. 1). From this measurement, we can deduce typical contrast of almost 20 %. Here, a free evolution time of T = 23 ms was used, which results in an enclosed area of A = 19 mm². The signal to noise ratio (SNR) for rotations with a detection noise of 0.1 % is in the order of more than 200. Nevertheless, from the fringe pattern shown in Fig. 1, we deduce a SNR of 30, which is currently limited by environmental vibrations. The resolution for rotations is 6.1 x 10-7 rad/s/Hz1/2.
Recent measruements have shown high integration stability which enables rotation measruements below 10-7 rad/s. This corresponds to a rotation sensor SNR of 450.