Applied Atom Interferometry: On the Fringe

Ch. J. Bordé

Gregory W. Hoth, Bruno Pelle, John E. Kitching +1 more

Light pulse atom interferometry can be used to realize high-performance sensors of accelerations and rotations. In order to broaden the range of applications of these sensors, it is desirable to reduce their size and complexity. Point source interferometry (PSI) is a promising technique for accomplishing both of these goals. With PSI, rotations are measured by detecting the orientation and frequency of spatial fringe patterns in the atomic state. These spatial fringes are primarily due to a correlation between an atom's initial velocity and its final position, which is created by the expansion of a cold atom cloud. However, the fringe patterns are also influenced by the structure of the initial atomic distribution. We summarize several methods that can be used to investigate the relationship between the spatial fringe pattern and the initial atomic distribution. This relationship will need to be understood in detail to realize an accurate gyroscope based on PSI.

Brian Anderson, T. L. Gustavson, Arnaud Landragin +4 more

Yun-Jhih Chen, Azure Hansen, M. Shuker +3 more

Point source atom interferometry (PSI) is an atom-optical method that measures one axis of acceleration and two axes of rotation from atom-interferometric fringe images. The number of fringes in an image can be less than or larger than one, depending on the system rotation rate and the atom interferometer's sensitivity setting. Previously used methods for analyzing the fringes, such as parametric fittings, are not suitable for a wide range of rotation rates. We introduce a new experimental method that is effective in either case. Our approach does not require prior knowledge of fringe contrast, orientation, frequency, and phase.

Yun-Jhih Chen, Azure Hansen, Moshe Shuker +3 more

Point source atom interferometry (PSI) uses the velocity distribution in a cold atom cloud to simultaneously measure one axis of acceleration and two axes of rotation from the spatial distribution of interferometer phase in an expanded cloud of atoms. Previously, the interferometer phase has been found from the phase, orientation, and period of the resulting spatial atomic interference fringe images. For practical applications in inertial sensing and precision measurement, it is important to be able to measure a wide range of system rotation rates, corresponding to interferograms with far less than one full interference fringe to very many fringes. Interferogram analysis techniques based on image processing used previously for PSI are challenging to implement for low rotation rates that generate less than one full interference fringe across the cloud. We introduce a new experimental method that is closely related to optical phase-shifting interferometry that is effective in extracting rotation values from signals consisting of fractional fringes as well as many fringes without prior knowledge of the rotation rate. The method finds the interferometer phase for each pixel in the image from four interferograms, each with a controlled Raman laser phase shift, to reconstruct the underlying atomic interferometer phase map without image processing.