The Laser Interferometer Gravitational Observatory (LIGO) is a collaboration of more than 1,000 scientists worldwide working toward a common goal: searching for gravitational waves. Gravitational waves are barely noticeable ripples in spacetime caused by black-hole binary systems and predicted by Albert Einstein in his General Theory of Relativity 100 years ago in 1916. LIGO was launched in 2002, but research has recently been catapulted forward with the development of a new technique that nearly doubles the sensitivity of the equipment used to detect these spacetime ripples.
Gooch & Housego, leaders in light measurement instrumentation, is looking forward to the progress LIGO is generating toward the search for gravitational waves by exploiting “squeezed light” and quantum entanglement to detect any passing gravity waves, but first, here is a brief breakdown on the science of measuring gravitational waves and the breakthrough of squeezed states of light.
To measure any passing gravitational waves, an inferometer is utilized. As the photodetector on the interferometer measures distances with a light beam, any variation in the measured distance suggests a recording of a ripple in spacetime. These ripples are minute, and measuring their presence requires extremely sensitive interferometers.
Presently, interferometers are faulted due to interference issues: at frequencies above several hundred hertz, the vacuum (zero-point) fluctuations of the electromagnetic field experiences very good sensitivity, but not perfect. The precise measurement of gravitational waves is invalid with very good sensitivity; it needs to be more accurate and precise.
By injecting squeezed light – light with photo-electron currents with extremely low noise – into the vacuum, sensitivity issues are alleviated and gravitational waves are able to be measured much more accurately. The squeezed states of light create entangled photons between the interferometer’s two mirrors. “Entangled” is a gentle misnomer since the subatomic particles are only invisibly connected, post-collision. This entangled state leads the particles to act as a single object. Therefore, measuring the state of one particle automatically gives the state for its entangled partner. On a much grander scale, “entangled” disturbances in one area of the universe can immediately affect other parts of the universe.
Advanced LIGO, due to be implemented in the near future, plans on incorporating the “squeezed light” approach to its upgraded interferometers. As technology advances, it moves closer to understanding the universe and all its surprises – such as learning about space by studying subatomic particles. Learn more about light measurement instrumentation by contacting Gooch & Housego at (800) 899-3171, and browse our website for information pertaining to the technological tools, services, and resources we offer.