The atomic-scale quantum properties of interfaces play a central role in numerous outstanding problems in physics, including control of the ubiquitous surface-mediated decoherence that currently limits a wide variety of quantum technologies, searches for beyond-standard-model physics at small length scales, and creation of scalable entangled quantum networks from disparate physical elements. In this experiment, we propose to construct a novel instrument that delivers unprecedented control over and metrology of active quantum surfaces. These surfaces are assembled by intentionally adsorbing and desorbing atoms whose quantum states are coherently controlled while coupled to and probed by Nitrogen Vacancy centers in diamond, a network of sub-surface quantum sensors in the form of point-like lattice defects. An ultra-high-vacuum cryogenic environment outfitted with tools for surface preparation and tools for optical and microwave control over the quantum states of atoms and solid-state defects will provide the extreme level of control necessary for surface studies at the quantum frontier. With this instrument, we will not only tackle head-on the main technical barrier to progress in quantum technologies, we will also nucleate future collaborations around a powerful quantum-enhanced platform for exploring fundamental physics in fields ranging from condensed matter to gravity.