Roughly 1,600 light years away, a binary star system known as J0806 has an incredibly short orbital period, with the two stars destined to merge. Depicted in this artist's vision is the death spiral of the stars, in which they will lose their orbital energy by generating gravitational waves. It is believed this star system could be one of the brightest sources of gravitational waves in our galaxy.
Credit: NASA/Tod Strohmayer (GSFC)/Dana Berry (Chandra X-Ray Observatory)
SYDNEY: 'Squeezing' laser light could significantly improve the accuracy of detectors searching for Einstein's elusive gravitational waves.
Gravitational waves were predicted by Einstein but have long remained undetected. To look for them, scientists use devices called laser interferometers, which measure the time it takes a split beam of laser light to travel between suspended mirrors. The waves are expected to distort the laser's travel time - but so far scientists can't measure this accurately enough.
The accuracy of these devices is limited by a quantum phenomenon of light called 'shot noise' - a type of electronic interference.
Using a new quality of laser light, which radiates much more calmly than a conventional laser, researchers reported yesterday in Nature Physics that they have curbed this interference and improved measuring accuracy in their detectors by roughly 50%.
"Squeezed light is a completely new approach," said physicist and lead author Roman Schnabel, from the Max Planck Institute for Gravitational Physics in Germany.
"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."
Travel time weakens waves
The findings are an an exciting step forward for the Laser Interferometry Gravitational-Wave Observatory (LIGO) project in its quest to observe gravitational waves using Earth-based detectors.
Albert Einstein first predicted the existence of gravitational waves in 1916 in his theory of general relativity. The presence of large amounts of mass or energy can distort the space-time fabric causing it to curve, and when they move suddenly, this curvature ripples outward - like the ripples in a pond after a fish jumps.
Violent astronomical events such as black hole collisions and supernovae can cause gravitational waves. In the immediate vicinity of these objects, gravitational waves would be immensely strong, said Schnabel.
However, after travelling billions of light years to reach the Earth they are significantly weakened, making them incredibly difficult to detect. So far they have eluded scientists.
Theoretical predictions based on Einstein's theory indicate current detectors must be improved by another factor of about three to 10 to reach a high probability of successful detection, said Schnabel.
"Squeezed light is a new technology, which has now proven to significantly contribute to realising this last factor," Schnabel said. "[And] the improvement factor of 1.5 is just the beginning. A factor of three due to squeezed light is possible with today's technology."
