Proposed gravitational wave detector uses matter interferometry

Ars Technica : Gravitational waves are theoretical weak distortions in spacetime caused by the movement of massive objects. Attempts to detect such waves involve building instruments of ever-increasing sensitivity. The standard device has been a laser interferometer , but a proposal from Peter Graham of Stanford University and his colleagues would rely instead on a matter interferometer. Their proposal involves cold gas clouds suspended in a vacuum. When the clouds are hit by a light pulse of a certain energy and duration, the gas is put in a superposition of excited and ground states, and of moving and stationary states. Their space-based system would use a single laser that passes through a pair of gas clouds separated by thousands of kilometers and then reflects back through the clouds to sequentially excite and de-excite the atoms. The alignment of the gas clouds and the time it takes the laser to travel between them in both directions should be nearly identical. Any variance in either would indicate the passage of a gravitational wave. If such a system can be put into place, it will likely have a greater sensitivity than current gravitational wave detectors.