Optical interferometer observatories such as LIGO have begun a new era of astrophysics by measuring the length of their vast arms to such precision that gravitational waves from distant collisions of black holes and neutron stars are now regularly observed. This past run, the global gravitational wave network itself entered a new era, whereby every detector has enhanced sensitivity using quantum squeezed states of light, limited by measurement back-action and optical loss. LIGO is now operating with its "Frequency-dependent squeezing"Â upgrade in its ongoing observing run. This technique suppresses back-action from quantum radiation pressure, bypassing trade-offs implied from Heisenberg uncertainty. This talk will: overview squeezing for enhancing astrophysics; introduce Cosmic Explorer, next-generation gravitational wave observatories with deep cosmological reach; and detail the GQuEST experiment at Caltech that hopes to realize different types of quantum enhancements to shed light on experimental techniques where quantum measurement and fundamental physics can collide.