The secret was a new modulation technique, Probabilistic Constellation Shaping. Instead of using all the networking's constellation points (the "alphabet of the transmission") equally, like typical fiber, it prefers those points with lower amplitudes -- the ones that are less susceptible to noise. That helps transmissions reach up to 30 percent further, since you can adapt the transmission rate to fit the channel. It's so effective that the team got close to the theoretical peak data speeds possible for the fiber connection.

You're likely not going to see these terabit fiber lines in regular use for a while, since there's a large gap between a field test and making commercially available lines. The timing might be ideal, mind you -- 5G cellular data is just gathering momentum, and telecoms will need gobs of bandwidth to cope with the increased demands. A realistic 1Tbps fiber option would make sure that the internet's wired backbones don't collapse under the load.