Squeezed Vacuum Injection in Advanced LIGO: Enhancing Gravitational-Wave Detection Using Quantum States of Light

Abstract

This Thesis describes the first use of squeezed vacuum states in the direct measurement of gravitational waves with the Advanced LIGO detectors. During the Observation Run O3, from April 1st, 2019 to March 27, 2020, squeezing improved the sensitivity of the LIGO interferometers to gravitational-wave signals above 50 Hz by up to 3 dB, increasing the expected detection rate by 40%-50%. This achievement is the culmination of decades of research to implement squeezed vacuum states in gravitational-wave detectors. This Thesis focuses on squeezing performance of the LIGO Livingston L1 detector, and the commissioning challenges that had to be overcome to make squeezing an integral part of the detector.