Tse, M.Yu, HaocunKijbunchoo, NutsineeFernandez-Galiana, A.Dupej, P.Barsotti, L.Blair, C. D.Brown, DanielDwyer, S.Effler, A.Evans, M.McClelland, DavidMcRae, TerrySlagmolen, BramWard, RobertHolland, NathanYap, Min Jet2020-11-062020-11-060031-9007http://hdl.handle.net/1885/214098The Laser Interferometer Gravitational Wave Observatory (LIGO) has been directly detecting gravitational waves from compact binary mergers since 2015. We report on the first use of squeezed vacuum states in the direct measurement of gravitational waves with the Advanced LIGO H1 and L1 detectors. This achievement is the culmination of decades of research to implement squeezed states in gravitational-wave detectors. During the ongoing O3 observation run, squeezed states are improving the sensitivity of the LIGO interferometers to signals above 50 Hz by up to 3 dB, thereby increasing the expected detection rate by 40% (H1) and 50% (L1).The authors also gratefully acknowledge the support of the Australian Research Council under the ARC Centre of Excellence for Gravitational Wave Discovery, Grant No. CE170100004 and Linkage Infrastructure, Equipment and Facilities Grant No. LE170100217; the National Science Foundation Graduate Research Fellowship under Grant No. 1122374; the Science and Technology Facilities Council of the United Kingdom, and the LIGO Scientific Collaboration Fellows program.application/pdfen-AU© 2019 American Physical Societyhttps://creativecommons.org/licenses/by/4.0/2019-12-0510.1103/PhysRevLett.123.2311072022-08-21Creative Commons Attribution 4.0 International license