Scientists say they have proven, for the first time, that quantum communication can connect multiple parties, like a three-way phone conversation. Except much, much faster.
Last year, for example, researchers at the University of Science and Technology in Shanghai measured how fast “simultaneous” really is. They set up two entangled photons 10 miles apart, then observed how fast a change of state in one would register in the other. The result, according to their paper, was 10,000 times the speed of light.
In (another) experiment, (Researchers) connected fiber optic cable to trailers more than 2,000 feet apart and away from the rooftop of their Canadian laboratory. The trailers contained detectors that could sense the entangled photons and timestamp the moment of their state change down to within three nanoseconds to preserve the integrity of the experiment. No other signal except the chatter of entangled particles could travel that quickly. And according to their paper, it worked. They called the demonstration a “milestone” in quantum mechanics.
The researchers say they could use this new ability to distribute quantum keys — which unlock encrypted data — or for “quantum secret sharing.” According to Chris Erven, of the University of Bristol, “This is the first experiment where you can now imagine a network of people connected in different ways using the correlations between three or more photons.”