1. Advanced LIGO A Quantum Limited Interferometer
LIGO I
Ad LIGO
Seismic
Suspension thermal
Test mass thermal
Quantum

2. Why use squeezed states?
Heisenberg  minimum uncertainty
Equal uncertainty in both quadratures
Squeezing  reduce uncertainty in one quadrature at the expense of increased uncertainty in orthogonal quadrature
Area in quadrature phase space conserved
Uncertainty circle  ellipse
How to squeeze?
Correlate quadratures
Why is it useful
Line up signal phasor with narrowest part of ellipse
Noise in measurement of that signal lower than the quantum noise limit

3. Sub-quantum-limited Advanced LIGOX+ X-
Quantum correlations (Buonanno and Chen)
Input squeezing

4. One way to squeeze
Vacuum seeded OPO
ANU group  quant-ph/