  Chemical chain reactions are known to enable extremely sensitive detection
schemes in chemical, biological, and medical analysis, and have even been used
in the search for dark matter. Here we show that coherent, ultracold chemical
reactions harbor great potential for quantum metrology: In an atom-molecule
Bose-Einstein condensate (BEC), a weak external perturbation can modify the
reaction dynamics and lead to the coherent creation of molecules in an
atom-dominant regime which can be selectively detected with modern
spectroscopic techniques. This promises to substantially improve the viability
of previously proposed BEC-based sensors for acceleration, gravitational waves,
and other physical quantities, including the detection of dark matter, that so
far relied on the detection of the tiny density modulations caused by the
creation of single phonons.
