Advances in quantum information science have brought on the possibility of a quantum internet—networks that carry information via photons in superpositions of states, called qubits, rather than the 0’s and 1’s that today’s networks shuttle from place to place.
In the last decade or so, researchers around the world have taken big steps toward building quantum networks. While many groups have started testing small networks tens of miles in size, major obstacles, including the need to develop a key piece of hardware, lie in the way of larger quantum networks. “There’s still lots of research to be demonstrated,” says Gabriella Carini of Brookhaven National Laboratory, New York, an organizer of a “Quantum Internet Blueprint Workshop” that took place in February. “But if you don’t have a vision, all the pieces won’t talk together.” The workshop was a step toward “establishing a nationwide quantum internet” in the US, an effort that has gained momentum with the National Quantum Initiative Act in 2018 and the recent budget request by the Trump administration to fund plans for a quantum internet.
The appeal of quantum networks lies in both immediately practical applications and potential advances for basic science research. One of the clearest applications is the ability to send secure messages without the threat of eavesdroppers. Because information is encoded with superpositions of states, any interception of a message would make qubits’ wave functions collapse, signaling that the message was intercepted.