  Progress in the quantum readout and control of mechanical devices from single
atoms to large masses may enable a first generation of experiments probing the
gravitational interaction in the quantum regime, conceivably within the next
decade. In this Snowmass whitepaper, we briefly outline the possibilities and
challenges facing the realization of these experiments. In particular, we
emphasize the need for detailed theories of modifications to the usual
effective QFT of gravitons in the infrared regime $E/L^3 \ll m_{\rm
Pl}/\ell_{\rm Pl}^3$ in which these experiments operate, and relations to
possible UV completions.

General Relativity and Quantum Cosmology;High Energy Physics - Phenomenology;Quantum Physics