Modeling of Cascaded Phase Sensing in Optical Fiber Using Squeezed Light

A key aspect of quantum optics and quantum metrology is the ability to measure beyond the classical (shot-noise) limit with certain photonic states. We present a layout for squeezing-enhanced multiparameter phase sensing in optical fibers. This sensor has its measurable phases in series, or cascaded, with evenly spaced Bragg reflectors defining the regions of fiber for those phase shifts. We discuss our model of this sensor, and how a bidirectional input configuration realizes nearly all of the potential enhancement from using squeezed light. Moreover, this quantum enhancement persists when these phases are highly correlated. Scaling up to many phases is feasible with a similarly large number of input pulses. This novel approach offers new perspectives on distributed fiber sensing and on multiparameter quantum metrology.