Quantum interferometric sensors

Quantum entanglement has the potential to revolutionize the entire field ofinterferometric sensing by providing many orders of magnitude improvement ininterferometer sensitivity. The quantum-entangled particle interferometerapproach is very general and applies to many types of interferometers. Inparticular, without nonlocal entanglement, a generic classical interferometerhas a statistical-sampling shot-noise limited sensitivity that scales like$1/\sqrt{N}$, where $N$ is the number of particles passing through theinterferometer per unit time. However, if carefully prepared quantumcorrelations are engineered between the particles, then the interferometersensitivity improves by a factor of $\sqrt{N}$ to scale like 1/N, which is thelimit imposed by the Heisenberg Uncertainty Principle. For opticalinterferometers operating at milliwatts of optical power, this quantumsensitivity boost corresponds to an eight-order-of-magnitude improvement ofsignal to noise. This effect can translate into a tremendous science pay-offfor space missions. For example, one application of this new effect is to fiberoptical gyroscopes for deep-space inertial guidance and tests of GeneralRelativity (Gravity Probe B). Another application is to ground and orbitingoptical interferometers for gravity wave detection, Laser InterferometerGravity Observatory (LIGO) and the European Laser Interferometer Space Antenna(LISA), respectively. Other applications are to Satellite-to-Satellite laserInterferometry (SSI) proposed for the next generation Gravity Recovery AndClimate Experiment (GRACE II).