I've been thinking about quantum computers (in a very limited way – one that doesn't involve understanding either them or quantum physics).
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The tricky thing about quantum mechanics, as exploited in quantum computing, is this thing called superposition. (I know: Mind the boggles.) A bit, in a quantum computer (a qubit), is like Schrödinger's cat; but instead of being both dead and alive it is both 0 and 1. This is all very well, but the implications for binary arithmetic are enormous. An 8-bit byte (yes, I used to think that was the only size, but Computer says No) has 64 values simultaneously. This makes quantum computers faster than ... any comparator you can think of. Here's what Wikipedia has to say on the subject:Quantum computers can be viewed as sampling from quantum systems that evolve in ways that may be described as operating on an enormous number of possibilities simultaneously, though still subject to strict computational constraints. By contrast, ordinary ("classical") computers operate according to deterministic rules. (A classical computer can, in principle, be replicated by a classical mechanical device, with only a simple multiple of time cost. On the other hand (it is believed), a quantum computer would require exponentially more time and energy to be simulated classically.) It is widely believed that a quantum computer could perform some calculations exponentially faster than any classical computer. For example, a large-scale quantum computer could break some widely used public-key cryptographic schemes...<tangent partial="a bit of that link, but there's much more">
As of 2025, quantum computers lack the processing power to break widely used cryptographic algorithms... however, because of the length of time required for migration to quantum-safe cryptography, cryptographers are already designing new algorithms to prepare for Y2Q or Q-Day, the day when current algorithms will be vulnerable to quantum computing attacks. Mosca's theorem ...<meta-tangent partial="as aforesaid">
In the field of cryptography, Mosca's theorem addresses the question of how soon an organization needs to act in order to protect its data from the threat of quantum computers. A quantum computer, once developed, would have the capacity to break the types of cryptography that have been widely used throughout the world, such as RSA. Although this is a known risk, no one knows exactly when a quantum computer will be created. Mosca's theorem provides a risk assessment framework... that can help organizations identify how quickly they need to start migrating to new methods of quantum-safe cryptography.
</meta-tangent>...provides the risk analysis framework that helps organizations identify how quickly they need to start migrating.
</tangent>...and aid physicists in performing physical simulations. However, current hardware implementations of quantum computation are largely experimental and only suitable for specialized tasks</background>
This reminds me of the Y2K problem, in that it is a technical problem with enormous ramifications that can and will (probably) be fixed at a cost of squillions of person-hours and forgotten almost immediately and/or pooh-poohed by everyone outside the IT industry – inspiring this early rant:
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Which reminds me of all the smart a*s (=ALECS, of course) who say things like "Remember all that Millennium Bug nonsense. The IT sales people used it as an excuse to sell a load of new kit. And what happened? Nothing! Not a thing, except that we all have to fill in 4-digit dates. I mean who needs to scroll down through dozens of 21st century dates when they're opening a new bank account, say?.... Er... maybe that's not the best of examples."
Well no, you bozo, I think. Nothing happened, not a thing, because for the last two or three years of the 20th century IT engineers were busy making sure it didn't.
</rant>
So anyway, although (as all the conditional language that you see in that article implies) quantum computing is not an everyday reality yet, when it is it will make traditional 'security' insecure: unless the industry has done a lot of preparation, public key encription (the jiggery pokery that makes it safe to store a credit card at a website) will be easily broken.
L'envoi
In May 2020, as the Johnson shower...I mean HMG, was starting to take Covid seriously (to the extent that 'taking seriously' was possible, given the juvenile lead) I wrote this.
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The post the other morning brought the music for next term's offering ...<parenthesis>
(if that's the mot juste – as there is no offeree, "so shaken as we are, so wan with care" as wossname put it). We'll be having virtual rehearsals. So individual choir members will hear themselves, but there won't be an audience.
</parenthesis>And the main piece for our Zoom rehearsals was the same mass. So my introduction to SATB choral singing...
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There had been "the sixth form choir", but that was just a (transparent?) ruse to flesh out our UCCA forms ("UCCA" being the fore-runner of UCAS) in the Lower VIth. Our repertoire extended to "Jesu, Joy of Man's Desiring" set for two parts, in Latin (it was a Catholic school after all) For years this was a party piece for me and my brother.Before that there had been a primary school choir (back before the philistines rewrote the curriculum), and a Gang Show (from which I can still see the Banda'd ...
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A Banda was a sort of pre-Xerox duplicating system (Wikipedia calls it a spirit duplicator), involving smudges and a strong whiff of meths. It's a wonder to me that there was not a rash of Banda-sniffing among school children (perhaps there was though; we had a very sheltered childhood)
</parenthesis>... copies, complete with a baffling typo at the end of "Steamboat Bill". The widow's words addressed to her children should have been "bless each honey lamb"; but our copies said "bless each honey bole" a mistake that my memory can't shake whenever I think of the tune. (We had no idea what a "bole" was at the time, but much of the socio-historic environment was foreign to us anyway: What was a steamboat?, what did "Crêpe on every steamboat" signify? What was a "honey lamb" and did it differ in any meaningful way from a "honey bole"?
</autobiographical_note>... was Beethoven's Mass in C. And I can't wait to hear what our MD makes of the first movement's less than decisive tempo marking. But what do I know? Far from indecisive it might just be extremely persnickety (and if I was feeling stronger I'd've stuck to my guns when the Autocorrect monster told me to break that last word up with an S).
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- Quantum stuff is more tricky than you can imagine, even if as a starting point you assume that everything you know is wrong. This recent podcast (well it was a plain old programme when I heard it, but now it's a podcast) gives you an idea.
My introductory paragraph on quantum computing leaves much to be despaired. I addressed with reason (a false friend if ever there was one in the quantum world) the subject of the many-valuedness of the qubit, without considering the role of quantum entanglement (which involves particles knowing about each other however distant from each other they may be. I KNOW. Don't ask.) There's much more to it than I suggested. But rather than try (vainly) to repair what I wrote, I'm leaving it as a historical document. - I concentrated on one aspect of the crimes made possible by quantum computing; financial security will be a thing of the past, until the financial world catches up. In the meantime, all those saved credit-card details will be a sitting duck.
But a recent podcast from the Goalhanger stables, The Rest is Classified, discusses other – possibly more consequential – implications concerning a differenr sort of security...<tangent>
A bit of background on that podcast:
</tangent>...There are gigabytes of encrypted messages collected by national spy agencies, just waiting for quantum decryption. When that becomes possible, the revelations will make several ententes far from cordiales.
