First gravity wave detector step closer to development

Physicists from The University of Western Australia are part of an international collaboration that has made a breakthrough in the development of the world’s first gravity wave detector.

The research was published this week in the international journal Nature Physics.

UWA’s Winthrop Professor David Blair, Director of the Australian International Gravitational Research Centre, said gravitational wave detectors were designed to allow people to tune in to the gravity waves that were first predicted by Einstein in 1916.

“Vast amounts of gravitational wave energy are believed to be continually passing through the Earth,” Professor Blair said.

“The collaboration of almost 1000 physicists has spent decades developing gravity receivers based on laser technology. They are designed to pick up powerful bursts of energy from the formation of black holes in the distant universe.

“The birth of a black hole creates a tsunami of rippling space. More energy is given out than our Sun emits in a billion years. These enormous bursts of energy travel at the speed of light, and so far we cannot even detect them.”

Professor Blair said over the past decades the collaboration had improved its detectors a millionfold, but then they hit a measurement barrier where the quantum uncertainty of light made better sensitivity impossible except by using enormously powerful laser light.

“This meant that the gravity waves remained beyond the reach of our detectors but this week’s announcement demonstrates, for the first time, the breaking of this quantum barrier.

“The quantum barrier arises because invisible quantum fluctuations leak into the detectors at the point of measurement. Although these fluctuations are invisible, physicists realised that they could be ‘squeezed’.

“Squeezing is a method of changing the randomness of light and is based on a weird phenomenon called quantum entanglement that Einstein dismissed as ‘spooky action at a distance’.

The technology used in this week’s announcement was pioneered at the Australian National University, refined by scientists at the Albert Einstein Institute in Germany and tested on a detector called GEO600 in Hannover.

The method is the first demonstration of quantum entanglement as a tool in improving sensitive instruments. Using squeezing, the scientists were able to measure vibrations 100,000 times smaller than the nucleus of a typical atom.

Five leading Australian universities, including UWA, the Australian National University, the University of Adelaide, the University of Melbourne and Monash University announced late last year that they had signed an agreement to plan and develop a collaborative project with the US-based Laser Interferometer Gravitational-wave Observatory (LIGO) Laboratory to build a gravitational wave observatory near Gingin, approximately 85 km north of Perth, Western Australia.

At UWA’s Gingin Gravity Centre, other methods of creating quantum entanglement are now being developed.

“This is just the start; gravity wave research is riding a wave of innovation and we have many more surprises and plenty of practical benefits coming out of our research,” Professor Blair said.

The US, UK and Germany have offered Australia a $140 million detector called LIGO-Australia to be installed at Gingin that would fill the need for a Southern Hemisphere detector.