I  have to confess to  always struggle a bit with "Quantum" ... anything.

My understanding  is that Quantum Computers look like this :-

,...

.....and need lots of liquid helium to work !!

So it wasn't immediately obvious how this :_

Fitted in.   Apparently it fits inside the helium  thingy !

I have to confess I've stored these things in my mind along side :-

1. Fusion Power.

2. Growing a new tooth when the old one goes rotten and drops out.

3. Totally self driving cars.

The  time scales for all coming to practical fruition seem to between the distant future and never !

... and the way we are going, one has to wonder if extinction will come first !

The latest issue of "IT Now" (the magazine you get if you're a member of the British Computer Society) has several articles about quantum computing, along with a cover exclaiming "MEET THE QUBIT". It's been progressing slowly and, frankly, I'm happy that it's been so slow - as they explain that it renders most of our encryption, especially that used on the Internet (which dates back to the 1950s), obsolete.

One of the articles delved into how SSL works (it involves logarithms, factors and very large numbers):

"For modulus sizes of 2048 bits, we would have to consume the equivalent amount of energy needed to boil all the oceans on the planet to factorise it."

It also says at the current rate of progress there's a 1-in-7 chance of 2048-bit encryption being broken by 2026 and a 1-in-2 chance by 2031. We don't have anything yet which is completely quantum-proof but as it dryly notes, research into new methods is continuing.

EDIT: And of course it's no wonder so much effort is being put into quantum computing. We're pushing the boundaries of physics with our current technology - modern chips have features set apart by just a few hundred atoms - hence a wholesale move to something new is required. We're currently at around 300 million transistors per square millimetre, FWIW, and it's insane if you think about it.

As I explained to an IT teacher last year (who used to mine me for info, as her degree was in business studies) - each of the shiny new PCs on the desks in the IT room had far more transistors than there are people in the world. And we just take it for granted!

What I don't have the faintest idea about is how you would go about manipulating qubits at the application level in order to solve mathematical equations - such as factorising 38 digit numbers into the product of 2 primes.  And perhaps more importantly how you would achieve this in 5 minutes instead of 1 septillion years using the sledgehammer approach to try every possibility

😊😊

What won't be so "interesting" is  if some Herbert actually makes this mind bending stuff work and some miscreant  gets their hands on the tech and drains your bank account. ... that flips it into the "f*cking annoying" category.

Maybe we will  have to go back queuing up at the bank  to get money out from a human teller and writing cheques out.

As I said on a different topic, the problem is not so much the technology as some of the human beings that use it.

As I think you are suggesting, the problem is that if the brute computing power is there then encryption ceases to be the security necessary for many transactions and were then in serious trouble.

These "transactions" include WhatsApp messages which boast end-to-end encryption and include messages sent by various ne'er-do-wells organising their nefarious activities

I wouldn't put it past the spooks to try and get a protoptye version of Google's "Willow" in order to take a peek at the contents - in secret ot course