Abstract
Quantum noise imposes a fundamental limitation on the sensitivity of interferometric gravitational-wave detectors like LIGO, manifesting as shot noise and quantum radiation pressure noise. Here, we present the first realization of frequency-dependent squeezing in full-scale gravitational-wave detectors, resulting in the reduction of both shot noise and quantum radiation pressure noise, with broadband detector enhancement from tens of hertz to several kilohertz. In the LIGO Hanford detector, squeezing reduced the detector noise amplitude by a factor of 1.6 (4.0 dB) near 1 kHz; in the Livingston detector, the noise reduction was a factor of 1.9 (5.8 dB). These improvements directly impact LIGO’s scientific output for high-frequency sources (e.g., binary neutron star postmerger physics). The improved low-frequency sensitivity, which boosted the detector range by 15%–18% with respect to no squeezing, corresponds to an increase in the astrophysical detection rate of up to 65%. Frequency-dependent squeezing was enabled by the addition of a 300-meter-long filter cavity to each detector as part of the LIGO A+ upgrade.
| Original language | English |
|---|---|
| Article number | 041021 |
| Number of pages | 14 |
| Journal | Physical Review X |
| Volume | 13 |
| Issue number | 4 |
| DOIs | |
| Publication status | Published - 30 Oct 2023 |
Bibliographical note
Acknowledgments:The authors gratefully acknowledge the support of the United States National Science Foundation (NSF) for the construction and operation of the LIGO Laboratory and Advanced LIGO as well as the Science and Technology Facilities Council (STFC) of the United Kingdom, and the Max-Planck-Society (MPS) for support of the construction of Advanced LIGO. Additional support for Advanced LIGO was provided by the Australian Research Council. The authors acknowledge the LIGO Scientific Collaboration Fellows program for additional support. LIGO was constructed by the California Institute of Technology and Massachusetts Institute of Technology with funding from the National Science Foundation and operates under Cooperative Agreement No. PHY-18671764464. Advanced LIGO was built under Grant No. PHY-18680823459. The A+ Upgrade to Advanced LIGO is supported by U.S. NSF Grant No. PHY-1834382 and United Kingdom STFC Grant No. ST/S00246/1, with additional support from the Australian Research Council. The authors thank Dennis Wilken, Vivishek Sudhir, James Lough, and Kim Burtnyk for carefully reading the manuscript.