High-contrast Bragg atom interferometer for testing continuous spontaneous localization

The continuous spontaneous localization (CSL) model is one of the most promising approaches to address the wave-function collapse problem in the measurement process of standard quantum mechanics. In this work, the effect of the CSL model on a Bragg atom interferometer is investigated. A Bragg interferometer achieving high fringe contrast of $99%$ is demonstrated, maintaining this performance level at an interrogation time of up to $T=60\phantom{\rule{0.16em}{0ex}}\phantom{\rule{0.16em}{0ex}}\mathrm{ms}$. The primary factors responsible for fringe contrast loss in the atom interferometer are systematically analyzed and corrected. This improvement establishes an upper limit of ${\ensuremath{\lambda}}_{\mathrm{CSL}}=1.27\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}\phantom{\rule{0.16em}{0ex}}\phantom{\rule{0.16em}{0ex}}{\mathrm{s}}^{\ensuremath{-}1}\phantom{\rule{0.16em}{0ex}}\phantom{\rule{0.16em}{0ex}}\mathrm{at}\phantom{\rule{0.16em}{0ex}}\phantom{\rule{0.16em}{0ex}}{r}_{C}={10}^{\ensuremath{-}5}\phantom{\rule{0.16em}{0ex}}\phantom{\rule{0.16em}{0ex}}\mathrm{m}$ for the CSL collapse rate, representing approximately 4 times enhancement over previous atom-interferometric constraints.