Interferometric phase sensing
Two coherent paths turn a tiny path-length difference into an intensity imbalance.
$$I_\pm=\tfrac{I_0}{2}[1\pm V\cos\phi]$$
Physical intuition
Two coherent paths turn a tiny path-length difference into an intensity imbalance.
Deep dive: physical mechanism
A Mach–Zehnder or Michelson interferometer converts differential phase to output-port populations or intensities.
What is measured experimentally?
Fringe shifts reveal displacement or refractive-index change.
Assumptions, noise and limitations
Vibration, thermal drift and finite visibility constrain precision.
Research and simulation exercise
Calculate shot-noise-limited phase sensitivity versus photon number.
Connect the ideas
Explore the chapter overview, learning path, and references.