Optical squeezing
One optical quadrature can fluctuate less than the vacuum reference.
$$\Delta X_\theta^2<1/4$$
Physical intuition
One optical quadrature can fluctuate less than the vacuum reference.
Deep dive: physical mechanism
Parametric interactions correlate field fluctuations and redistribute noise between conjugate quadratures.
What is measured experimentally?
Homodyne detection measures quadrature variance versus local oscillator phase.
Assumptions, noise and limitations
Loss mixes in vacuum noise and degrades observed squeezing.
Research and simulation exercise
Propagate a squeezed state through a lossy channel.
Connect the ideas
Explore the chapter overview, learning path, and references.