Description: Quantum Sensors are used in a wide variety of applications including microscopy, positioning systems, communication technology, electric and magnetic field sensors, as well as geophysical areas. Significant gains from Quantum Sensors include technologies important for a range of NASA missions including efficient photon detection, optical clocks, gravimetry, gravitational wave sensing, ranging, and optical interferometry. Entangled multi-particle states used for precision measurements provide tools to reach the so-called Heisenberg limit and thus, overcome the shot-noise limit (fundamental noise limit for classical systems) and hence perform measurements at a precision unachievable for classical sensors. Quantum photon-number states, also known as Fock states, are the key ingredient to realizing the most useful entangled multi-particle states. Furthermore, photon-number states have applications in quantum communication and quantum information sciences as well. Physical Sciences Inc. (PSI) and the University of Illinois Urbana-Champaign (UIUC) will develop a robust and deterministic source of photon-number states. The source is based on spontaneous parametric down-conversion inside a low-loss optical loop a switchable quantum buffer and will produce quantum photon-number states on demand at the telecommunications wavelength, thus providing a key resource for advanced quantum sensors.

Benefits: Exotic quantum states – including squeezed states, entangled states, and photon-number states – have a range of applications for multiple NASA missions and programmatic needs. For example, photon-number states are directly relevant for characterizing energy-resolving single-photon detectors, and as a resource to create optimal states for optical metrology, such as N00N states. Controllable production of fixed photon numbers in multiple spatial modes is also an assumed resource for advanced optical quantum processing, e.g., boson sampling.