Quantum Resistance and the Signal Protocol

Seems weird to be assuming what's possible based on current technical obstruction. If you trace CPUs development, or many other technologies, many people with deep technical knowledge were certain about some thresholds which we have long passed. This bias even had some name which I forgot.

To describe a set of classical bits completely, you need a probability distribution over the whole system (including possible classical correlations induced by the crosstalk that OP spoke about). That probability distribution is a stochastic vector that has 2^n real positive components if we have n bits.

To describe a set of qubits completely, you need at least a "quantum probability distribution", i.e. a ket that has 2^n complex components (I am skipping the discussion of density matrices).

Both the classical and quantum description of the bits requires exponentially many real numbers. This exponential behavior on its own is not enough to the explain "quantum computational advantage". The exponential behavior is well known in plenty of classical contexts (e.g. under the name "curse of dimensionality") and classically solved with Monte Carlo modeling.

Scott Aaronson's lecture notes cover that quite well.

At the end, the issue of crosstalk is modeled in a very similar way in the quantum and classical case, and if it forbids the existence of a quantum computer, it should forbid the existence of classical ones as well. In both cases it is the use of linear binary (or stabilizer) codes that solves that issue.

Are you suggesting that limiting interference will be a practical dead end that is prevents advancement?

Either way that would be a pretty significant claim. There are lots of research directions being pursued and plenty of smart people think it’s worth trying.

The initial shared private key exchange could be done with more expensive, quantum resistant cryptography but the actual communication could be done through symmetric encryption.

https://www.inkandswitch.com/backchannel/

For the key exchange itself ("PAKE") maybe something like this: https://journal-home.s3.ap-northeast-2.amazonaws.com/site/ic...

And for the symmetric encryption: https://github.com/Steppenwolfe65/eAES

"Instead of bits as in a classical computer, quantum computers operate on qubits. Rather than 0 or 1, qubits can exist in a superposition of states, in some sense allowing them to be both values at once."

'Instead of beads as in a classical abacus, our Quabacus operates on Quabeads! Rather than positions 0 or 1, quabeads can be in both positions at once!'

Beads that are simultaneously in both positions sounds like a f$@!#g annoying glitch and not a feature - how does that help anyone record or calculate numbers? ('Would someone take a look a this broken Quabacus-abacus and resolve these g#$%!m glitching quabeads?!!!') It mocks the non-technical reader, who assumes they must have been given enough information to understand why it's faster and possibly how it works, but can't figure it out.

They have not been given enough. Does anyone who perhaps understands it better than I do want to take a stab at a new commonplace explanation, one that connects the dots between quantum superposition and performance (for certain calculations)?