For those readers responsible for Internet security at their employers, and those who use their computers to communicate securely with other sites, such as banking facilities and the like – there, that’s just about everyone – there has been, at least for the knowledgeable, the oncoming terror of Q-Day. This appellation is applied to the day that a quantum computer successfully breaks the encryption we use on the Internet.
But how would a quantum computer accomplish this terror? First, keep in mind that I’m just an obsolete software engineer, still employed, meaning I do not work on quantum computers, and thus only know what I read, and I do not know nor study quantum mechanics. The most common approach that I’ve seen mentioned is to implement something called Shor’s algorithm, developed by Peter Shor, that leverages the capability of qubits, the analog to classical computers’ bits, to assume multiple values simultaneously, and execute the parallel calculations simultaneously, which makes them capable of breaking encryption.
Yes, that’s very high level and rough.
So. What am I talking about? Classical quantum mechanics is based on an assumption that it’s a continuous view of quantum space (Hilbert space, actually). But, and skipping over the assertions and arguments and discussion that are way beyond me, what if a better representation of quantum mechanics is one based on a discrete view of quantum space? A quantum physicist at Oxford named Tim Palmer has proposed just such a view, one in which irrational numbers are excluded. He calls it rational quantum mechanics, or RaQM.
And what does it mean for Q-Day? The above link, which is to a paywalled NewScientist article, suggests that Q-Day may never come. Using the theory, a different constraint on the number of possible values a qubit may simultaneously assume, a constraint much lower than Shor’s algorithm requires.
So if disaster seemed imminent to you, or you hadn’t heard of Q-Day, be aware that it may never occur. Not to say some clever cookie will never come up with some other method for cracking encryption, but using quantum mechanics may never work.
More importantly, this may generate the observation that cracks classical quantum mechanics theory. Most theories are used and accepted until some observation of a phenomena occurs that the theory cannot explain. While We can’t seem to get there! is not as positive as, say, observing what we now call plate tectonics and realizing theories assuming the Earth is a static ball of water and continents, it would be a significant observation, and would force a rethinking of quantum mechanics theory.
