High Data-Rate Atom Interferometry for Measuring Dynamic Inertial Conditions

Light pulse atom interferometers have demonstrated remarkable sensitivity and stability for acceleration and rotation rate measurement. However, typical manifestations are designed for laboratory environments and thus rely on a fixed magnitude and direction of gravity, and limited ambient rotation rate. We have enhanced the application space of atom interferometers towards more dynamic environments, with special attention for inertial navigation. I present our work in the domain of short time-of-flight atom interferometry, whereby the magnitude of ensemble excursion is constrained. The limited interrogation time results in a significant loss of sensitivity. We recover a fraction of the lost sensitivity by operating with an enhanced duty-cycle and data-rate. To demonstrate this concept, we construct an atom interferometer accelerometer capable of operating at data-rates as high as 300 Hz with sensitivities at μg/rtHz levels, which represents a competitive figure for inertial navigation application. For the bulk of this work, we demonstrate a dual-axis sensor capable of simultaneous acceleration and rotation-rate measurements. The sensor relies on a technique we refer to as "ensemble exchange" which provides a high flux source of ultracold atoms by swapping atomic ensembles between two MOTs. We achieve a steady-state atom number of 7e6 atoms/shot using a minimal loading time of a few milliseconds each shot. Furthermore, we find this technique to be robust under dynamic conditions as large as 10 g of acceleration and 20 rad/s of rotation rate, representing a significant enhancement in ultra-cold atom sample preparation. The sensor achieves μg/rtHz and μrad/s/rtHz sensitivities, making this technique a compelling prospect for inertial navigation applications. Through the use of auxiliary cosensors and a real-time combinatorial loop with feedforward and feedback mechanisms, we demonstrate an unprecedented enhancement of the sensor dynamic range up to 20 mg. Finally, I will discuss a novel manifestation of short time-of-flight atom interferometry in a warm atomic vapor, which avoids the complication of cold sample preparation and has the potential for significantly simplified laser systems.Sandia National Laboratories, Laboratory Directed Research and Development, Defense Advanced Research Projects AgencyPhysicsDoctoralUniversity of New Mexico. Dept. of Physics & AstronomyBiedermann, GrantCaves, CarltonDeutsch, IvanSchwindt, Pete