Post-quantum Cryptography: Securing Data in the Age of Quantum Computers

Computation pervades today’s world. This is a fast-changing field – one promising technique, supersingular isogeny Diffie-Hellman key exchange, was considered secure by many until it was utterly broken by Wouter Castryck and Thomas Decru last year. Perhaps if we built our circuits or gates using lasers, we could build new kinds of gates in addition to the basic ones – maybe a prism “naturally” computes a square root or something. As people explored these ideas, they found something amazing: the principles of quantum mechanics enabled a set of gates that were utterly impossible to build using electronics. On a quantum computer, one could have a “square root of not” gate – something which would produce the opposite of the input, but only after passing through two such gates!