[raziel2701]

I don't believe the LIGO experiment is utilizing entangled photons. This experiment is using a very different type of interferometer because they're trying to be sensitive to rotations, whereas LIGO's interferometer is for measuring changes in length. LIGO's biggest problem is how to minimize losses in their mirrors.

[bowsamic]

LIGO could potentially utilise EPR entanglement between photons in different parts of the detector but it does not do so yet. That’s a potential future development. It does use quantum squeezing though