New technique improves performance of gravitational wave detectors
doi:10.1038/nindia.2020.114 Published online 23 July 2020
Gravitational waves emanate from violent and energetic events such as colliding black holes, supernovae and colliding neutron stars. These waves then travel at the speed of light, carrying with them information about their origins, as well as clues to the nature of gravity itself.
Astrophysicists have now devised a technique that can improve the efficiency and sensitivity of the US-based Laser Interferometer Gravitational-wave Observatory (LIGO), which is designed to detect gravitational waves.
Gravitational waves stretch and compress space. In LIGO, this causes one arm of the interferometer to get longer while the other gets shorter as long as the wave passes. Such changes in arm length also alter the properties of the laser beam, which is used as a probe to detect the signals of gravitational waves.
The change in arm length caused by a gravitational wave can be as small as 1/10,000th the width of a proton. This, falling within the realm of quantum mechanics, is subject to the laws of quantum mechanics. At this level, quantum fluctuations generate noise that affects the results of LIGO.
The scientists, including an astrophysicist from the Inter-University Centre for Astronomy and Astrophysics in Pune, India, developed a quantum correlation that has been shown to experimentally minimise such noises inside the vacuum environment of LIGO, using a laser light of specific intensity.
This technique has allowed the LIGO to go from detecting roughly one astrophysical event per month to about one per week.
1. Yu, H. et al. Quantum correlations between light and the kilogram-mass mirrors of LIGO. Nature. 583 (2020) Doi:10.1038/s41586-020-2420-8