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An ideal system is a highly reflecting mirror whose motion is sensed by monochromatic light, which is photoelectrically detected with high quantum efficiency. A quantum optomechanical experiment is achieved if the quantum uncertainties of light and mirror motion influence each other, ultimately leading to the observation of entanglement between optical and motional degrees of freedom. In AVS Quantum Science, researchers from Hamburg University in Germany review research on gravitational wave detectors as a historical example of quantum technologies and examine the fundamental research on the connection between quantum physics and gravity. Gravitational wave astronomy requires unprecedented sensitivities for measuring the...

Astrophysicists may have detected gravitational waves last week from the collision of two neutron stars in a distant galaxy — and telescopes trained on the same region might also have spotted the event. Rumours to that effect are spreading fast online, much to researchers’ excitement. Such a detection could mark a new era of astronomy: one in which phenomena are both seen by conventional telescopes and ‘heard’ as vibrations in the fabric of space-time. “It would be an incredible advance in our understanding,” says Stuart Shapiro, an astrophysicist at the University of Illinois at Urbana–Champaign. Scientists who work with gravitational-wave...

The apocalypse is still on, apparently — at least in a galaxy about 3.5 billion light-years from here. Last winter, a team of Caltech astronomers reported that two supermassive black holes appeared to be spiraling together toward a cataclysmic collision that could bring down the curtains in that galaxy. The evidence was a rhythmic flickering from the galaxy’s nucleus, a quasar known as PG 1302-102, which Matthew Graham and his colleagues interpreted as the fatal mating dance of a pair of black holes with a total mass of more than a billion suns. Their merger, the astronomers calculated, could release...

Okay, but what exactly is a gravitational wave and how could they help us crack the conundrum of the black hole code? A gravitational wave is akin to a ripple in space-time. Albert Einstein predicted that massive bodies changing speed or direction generate these gravitational waves. Picture bodies like a pair of black holes orbiting each other. This then creates a gravitational wave that ripples outwards, like a disturbance in a still pool of water after a leaf has dropped onto its surface and ripples are sent across the surface. Like star-crossed lovers, the black holes of two merging galaxies...