Abstract

A geometric approach to the analysis of interferometers is presented in which beam splitters and phase shifters are described as performing rotations in an abstract three space on the state vector of the light. This formulation allows one to take full advantage of representation theory for the group SU(2) in analyzing interferometer sensitivity. With these techniques it is easy to show that in conventional interferometry, where light enters only one input port, the phase sensitivity scales as the inverse square root of the number of photons that pass through the interferometer during measurement time.

© 1986 Optical Society of America