[Cryptography] Why full-fledged quantum computers might always be five years away

[Peter Gutmann]

Jon Callas <jon at callas.org> writes:

>And analog computers were a thing ages ago, there's no reason they can't be
>again.

They're still a thing today, everyone here has several of them in places like
their living room: In their TV, in their stereo/sound system/whatever, in
their phone, in all sorts of other places, anything that has an amplifier in
it.  For non-electronics people, the devices that perform this function are
called op amps.  They're called op amps because it's short for operational
amplifier, a high-gain differential-voltage controlled amplifier originally
created to perform arithmetic operations, addition, subtraction, integration,
differentiation, summation, logarithms, etc, for use in analog computers.

Arguably the op amp(s) in your TV are even more of a computer than a "quantum
computer" because they can perform operations over arbitrary input values
(within electrical limits) without having to be rewired every time an input
value changes.

In terms of actual analog computers that don't rely on QC-style sleight-of-
word trickery to get their name, there are a number of companies working on
them, principally chasing the AI gravy train, because you can calculate to
more or less arbitrary precision for free.  It's all experimental or chasing
VC funding though AFAIK.

Peter.