A technological revolution is underway, as scientists are learning to harness and control the power of quantum mechanics. Fields such as quantum information science, nanotechnology, and materials science have probed continually deeper into the atomic realm, pushing present-day sensor technology to its limits. Quantum sensors, which operate according to uniquely quantum mechanical laws, have the potential to achieve the highest possible sensitivity, efficiency, and precision allowed by nature. Quantum information science provides systematic methodologies for designing such sensors, including algorithms and techniques for overcoming unwanted noise and artifacts. By introducing unprecedented exploration and control of the nano-scale world, quantum sensors will provide new insights and discoveries in material structures, three-dimensional molecular imaging, spintronics, and more. This symposium will highlight three experimental approaches to quantum sensors: magnetic resonance force microscopy, scanning probe microscopy with a diamond tip, and neutron interferometry. The speakers will explore the key questions, challenges, and breakthroughs in their respective approaches and discuss the important roles quantum sensors will play in science and next-generation technology.