Trapping a Gravity Wave Using Entangled Photons

A gravity wave is a fluctuation, or a ripple, in the curvature of space-time, which travels as a wave, outward from a moving object or system of objects. For example, an accelerating mass loses its entire energy when exceeding certain levels, which creates gravitational module in the form of a ripple.

Scientists have developed a sort of quantum "ruler" that could detect the faintest gravitational waves. For now, physicists are attempting to detect the gravitational waves using interferometers, which split a light beam into two waves and then recombine them to create interference fringes.

When passing through the interferometer, the gravity wave would alter the distance that one beam travels relative to the other and the interference fringed will detect the change. This technique has its limitations, as it can't measure a change smaller than the size of the fringes, size limited by the wavelength of the light used.

A team of researchers led by Shigeki Takeuchi at Hokkaido University in Japan have found a way to overcome these problems by using a beam of four entangled photons, which reduces by half the spacing between the fringes, thus enabling a more precise detection of the faint waves, otherwise impossible to detect.

"Effectively we have four photons passing through our apparatus where otherwise we would have only one," Takeuchi says. "It is essential to increase the number of entangled photons. There is really no other way to improve precision."

Quantum entanglement is a mechanical phenomenon that allows for a description of the quantum states of two or more objects with reference to each other and already has various applications in fields like quantum computing and quantum cryptography.

This technique has even been used to experimentally realize quantum teleportation, a method of transferring a quantum state to a random distant location through a distributed entangled state and the transmission of some classical information.