The Quantum Secret

Alice has a message she does not want Eve to read. That is the whole of cryptography, and it is where this comic starts - with a note passed across a classroom, and a question a reader of ten can already ask: how do you send a secret when someone is listening? Over fifteen chapters Alice, Bob, Eve and a companion called Qubit work their way from that question to quantum key distribution, and the route is the point. A lock and a key are examined first, because the idea of a shared secret has to exist before anything quantum can improve on it. Then the strange rules arrive one at a time: a world where things are not decided until they are looked at, a bit that can be both, and the measurement rule that makes quantum physics useful for secrecy rather than merely odd. By chapter seven the reader has what they need to see why a quantum channel is different, and chapters eight to ten walk through an exchange and then through Eve's attempt to intercept it - the attempt that fails in a way no classical eavesdropper's does, because looking leaves a mark. The last five chapters open outward: entangled pairs, teleportation of a state rather than of matter, what a quantum computer would do to the codes we use today, and a final mission that puts the pieces together. Where a real calculation is needed, it is shown and checked; where a picture is a metaphor, the comic says so, because a reader who cannot tell the difference has been taught something false. It is a story rather than a lesson with drawings attached. Alice wants something, Eve wants something else, and the physics is what decides which of them gets it. The science was designed first and the plot built to carry it, so nothing true is bent for the sake of a panel. For readers roughly nine to twelve, and for the adult reading over their shoulder who would like to know how quantum key distribution actually works.