Future Underwater Quantum Links May Help Secure Communications for Submarines

(SpectrumIEEE) Underwater quantum links are possible across 30 meters (100 feet) of turbulent water, scientists have shown. Such findings could help to one day secure quantum communications for submarines.
Researchers have investigated establishing quantum communications links through water. Such work could lead to secure quantum communications between submarines and surface vessels, and with other subs, aircraft, or even satellites.
Although water absorbs many radio waves, it’s transparent to optical wavelengths between 400 to 500 nanometers, roughly corresponding to green, blue, and violet light.
In the new study, researchers experimented with quantum communications in a “flume tank,” a water tank in which scientists can generate waves to mimic the ocean.
The researchers achieved quantum communication at up to 72 kilobits per second across up to 30 meters of turbulent water, the longest distance yet reported for such links. Unexpectedly, the researchers found they could keep quantum communication going even while the transmitter moved down the flume tank. The researchers aim to experiment with faster electronics and beam-tracking tools, “which will allow us to communicate between two- or multi-parties that are actually floating and moving around in the water.”