When a Quantum Computer Is Able to Break Our Encryption, It Won’t Be a Secret

On Oct. 23, 2019, Google published a groundbreaking scientific research article announcing one of the “holy grails” of quantum computing research: For the first time ever, a quantum computer had solved a mathematical problem faster than the world’s fastest supercomputer. In order to maximize impact, the Google team had kept the article tightly under wraps in the lead-up to publication—unusually, they had not posted a preprint to the arXiv preprint server.

The article sank with barely a ripple in the expert academic community.

That wasn’t because anyone disputed the significance of the Google team’s milestone. Many experts still consider Google’s demonstration to be the most important milestone in the history of quantum computing, comparable to the Wright brothers’ first flight in 1903. But most experts in the field had already read the article. A month earlier, a NASA employee who was involved with the research had accidentally posted a draft of the article on NASA’s public web site. It was online for only a few hours before being taken back down, but that was long enough. Schrödinger’s cat was out of the bag.

This anecdote illustrates a fact with important policy implications: It is very difficult to keep groundbreaking progress in quantum computing secret.

One of the most important quantum computing algorithms, known as Shor’s algorithm, would allow a large-scale quantum computer to quickly break essentially all of the encryption systems that are currently used to secure internet traffic against interception.