Optimal Control for Robust Atomic Fountain Interferometers

Atomic fountain interferometers [1] provide precision measurements of gravitational fields with unprecedented sensitivity. This provides a wealth of possible applications, from fundamental science such as testing the equivalence principle, to next-generation inertial navigation systems. Fundamentally, the atom interferometer is implemented by laser pulses driving Bragg-transitions between the momentum states of the atomic cloud. Signal contrast is limited by the ability to realize large-momentum-transfer atomic mirrors and beamsplitters with high fidelity and robustness with respect to laser amplitudes and initial velocity distribution of the atoms. Starting from a pulse scheme based on rapid adiabatic passage, we employ Krotov's method of numerical optimal control and ensemble optimization [2] to find shaped laser pulses that yield an increase in fidelity and robustness by roughly two orders of magnitude.

[1] T. Kovachy et al., Nature 528, 530 (2015)
[2] M. Goerz et al., Phys. Rev. A 90, 032329 (2014).