Fine-tuning lasers to detect gravitational waves

Cosmos : “‘Squeezing’ laser light could significantly improve the accuracy of detectors searching for Einstein’s elusive gravitational waves,” writes Myles Gough for Cosmos magazine. Because gravitational waves, which are generated by violent astronomical events, have traveled billions of light-years before reaching Earth, they are greatly weakened and thus difficult to detect. Until now, the accuracy of the laser interferometers used to detect the waves has been limited by a quantum phenomenon of light called “shot noise"—a type of electronic interference. To overcome this problem, Roman Schnabel of the Max Planck Institute for Gravitational Physics in Germany and coworkers perfected a method of “squeezing” the light to reduce the noise to less than that dictated by the Heisenberg uncertainty principle and then feeding the squeezed light into the interferometer, along with the normal laser light, which resulted in a laser beam with a much more uniform intensity. “One can say that for the first time a ‘technology’ is based on one of the distinct features of quantum physics itself. We were able to leave the stage of laboratory experiments and realize a real application,” said Schnabel. The group’s results , published in Nature Physics, are an exciting step forward for the Laser Interferometry Gravitational-Wave Observatory (LIGO) project in its quest to observe gravitational waves using Earth-based detectors.