Robust and deterministic source of photon number states

Quantum Sensors have use 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 ndash; a switchable quantum lsquo;bufferrsquo; ndash; and will produce quantum photon-number states on demand at the telecommunications wavelength, thus providing a key resource for advanced quantum sensors.