Keeping communication safe from prying eyes and ears. It's why the ancient Greeks had their whispers. It's what inspired the enigma machine of World War II, and today, digital encryption. But all of these could be compromised. The problem is when someone listens in on secret communication, or copies sensitive data, it can be impossible to tell.
But today's engineers working on communication systems of tomorrow have a plan to change that. They call it "secure quantum communication." Sorry, hackers.

Credit: Fast Draw/National Science Foundation