LIGO’s Advanced Tech for Gravitational Wave Discovery

A team of researchers at the Laser Interferometer Gravitational-Wave Observatory (LIGO) in the United States has enhanced their ability to detect gravitational waves by implementing a technique called squeezed light. This development, detailed in a paper in Science, involved modifications that reduced quantum flickering, leading to an increase in detected gravitational waves.

In an accompanying article, Yoichi Aso from the National Astronomical Observatory of Japan discusses how LIGO operates and highlights the significance of these advancements in improving detection sensitivity.

The LIGO project previously gained global recognition when a team at Caltech was awarded the Nobel Prize in Physics in 2017 for their contributions to detecting gravitational waves, first observed in 2015. These waves are distortions in space-time, originally predicted by Albert Einstein. Since then, LIGO has been constantly refining its technology to detect more waves and improve its sensitivity.

LIGO works by splitting a laser into two beams that travel down two long, perpendicular tunnels, where they are reflected back by mirrors. When the returning beams show differences, it indicates the presence of gravitational waves, which stretch the space-time fabric in the tunnels.

From the outset, LIGO's scientists understood the challenge of differentiating gravitational waves from quantum field noise, which led to continuous efforts to improve the detector's sensitivity. In this latest update, the team introduced a special crystal, along with new mirrors and lenses, to modify the light in the laser beams, reducing the quantum flickering by squeezing the light into a quantum state.

Initially, these upgrades mainly improved the detection of high-frequency gravitational waves. After additional adjustments, the system could also detect lower-frequency waves. These combined improvements had a dramatic effect, doubling the number of gravitational waves detected. This allows researchers to explore a larger portion of the universe and could lead to new insights, such as the study of black hole mergers from the early stages of the universe, near the formation of the first stars.