The ability to send entangled photons to the ISS would be a stepping stone to a global quantum internet and could test the link between quantum mechanics and relativity

One of the great mysteries of modern physics is the link between quantum mechanics and general relativity or gravity. But quantum phenomena generally occur on the very smallest scales while gravity generally crops on the largest scales. Never the twain shall meet.

At least, not without some clever thinking. One idea is to entangle a pair of photons, hang on to one and send the other across a distance so vast that gravity is significant, in other words, far enough for the gravitational curvature of space to come into play.

The issue in question is whether the entanglement--a purely quantum phenomenon--'feels' this curvature in the same way as purely classical things, like humans.

Therequired distance isn't that far--a few hundred kilometres should do the trick.

But there's a problem. The furthest scientists have sent entangled photons is just 144kilometres.and because of atmospheric losses and the curvature of the Earth's surface, the only way to go further is to fire photons straight upwards, into space.

Today,Thomas Scheidl at theAustrian Academy of Sciences in Vienna and a couple of pals suggests a simple and relatively cheap way of doing these kinds of experiments for the first time using the International Space Station (ISS), which orbits at an altitude of about 400 kilometres.

Their plan is to create entangled photons on the ground and beam them up to the ISS. That gets around one important problem with this kind of work, which is that much of the hardware needed for creating entangled photons--the lasers, nonlinear materials etc--are not yet qualified for use in space and getting such a qualification is an expensive business.

So leaving all this stuff on the ground is a sensible idea. All you need in space is a sensor capable of detecting photons and their polarisation. In other words, a camera.

See the original post:

Europe Proposes Cheap Quantum Optics Link to the Space Station