Fundamental limitations of cavity-assisted atom interferometry

<p>Atom interferometers employing optical cavities to enhance the beam splitter pulses promise significant<br> advances in science and technology, notably for future gravitational wave detectors. Long cavities, on the<br> scale of hundreds of meters, have been proposed in experiments aiming to observe gravitational waves with<br> frequencies below 1 Hz, where laser interferometers, such as LIGO, have poor sensitivity. Alternatively, short<br> cavities have also been proposed for enhancing the sensitivity of more portable atom interferometers.We explore<br> the fundamental limitations of two-mirror cavities for atomic beam splitting, and establish upper bounds on the<br> temperature of the atomic ensemble as a function of cavity length and three design parameters: the cavity g factor,<br> the bandwidth, and the optical suppression factor of the first and second order spatial modes. A lower bound to the<br> cavity bandwidth is found which avoids elongation of the interaction time and maximizes power enhancement.<br> An upper limit to cavity length is found for symmetric two-mirror cavities, restricting the practicality of long<br> baseline detectors. For shorter cavities, an upper limit on the beam size was derived from the geometrical stability<br> of the cavity. These findings aim to aid the design of current and future cavity-assisted atom interferometers.