[The_rationalist]

> which seems probable, as we are progressing fast in the number of qubits we can keep together Probable? Ridiculous:

×there are still no hardware implementation of a single logic gate despite what? 40 years of research? ×stability of qubits are pathetic. ×no software stack (almost) ×Number of qubits are ridiculous and 40 years of research can't even make a consensus on how much qubits are needed for beating a CPU on at least one task. Even if quantum could(I strongly doubt that and quantum speedup has never been shown empirically) reduce complexity on some algorithms, the constant factor has no way to be handled with 50qbits, more like 1000000 qbits at minimum. ×no sign of needed breakthrough in error correcting codes.

I consider quantum speedup to be theoretically flawed, based on an interpretation of quantum mechanics needing "parallel worlds" which necessitate a misunderstanding of causality to make sense.

I consider quantum speedup to be flawed in practice too as order of magnitude of order of magnitude progress is needed and the trend is: no progress or very slow progress.

Thus quantum computing is like a vaporware, which take funds that would be far better allocated at e.g medicine, AGI, or ASICS.

[semi-extrinsic]

While I agree that QC is far from cracking any encryption today or in the near future; this

> theoretically flawed, based on an interpretation of quantum mechanics needing "parallel worlds"

is patently false. There is nothing in QC that would stop working under the good ole' Copenhagen interpretation.

In fact, if there was even a theoretical possibility that a QC experiment would work only in some QM interpretations, they would no longer be interpretations, but falsifiable hypotheses.

[im3w1l]

Copenhagen postulates collapse, no? If collapses turn out to happen at problematic times or because of problematic conditions, it could potentially doom quantum computers.

In contrast, many worlds says basically: There is no collapse. Ever.

The fact that no one has found what triggers collapse yet is to me evidence that Copenhagen is false.

Pilot wave theory on the other hand is, afaiu completely equivalent to many worlds, but less philosophically convincing.

Where many worlds says there is only the wave function, pilot wave says there is a wave function but also the material world. And material world is a sort of "view" of the wave function. Continuously rederived from it. But the interesting thing is, this material world has no causal consequences. All causality stems from the wave function and its evolution. This is the compromise to get same predictions as many worlds.

[krastanov]

Various interpretation postulate collapses under specific conditions, while other formalisms postulate something mathematically/observationally equivalent at mathematically/observationally equivalent conditions. In particular "problematic collapses" are a thing all quantum computing researchers have to deal with in their work. It is one of the largest subfields of this research program actually (practical quantum error correction).

[semi-extrinsic]

> The fact that no one has found what triggers collapse yet is to me evidence that Copenhagen is false.

It' just the same as "no one has found what triggers a split between worlds, and why the physical reality we observe is following this particular one of the many worlds".

[The_rationalist]

Well if Occam's razor is not enough, you must know that both many world interpretation of QM and hortodox view of QM are refuted. The one remaining is the statistical one that is: QM is a map not the territory, QM descriptions are description of optimal use of our knowledge (or lack of) on a system. Sufficient knowledge of the environment allow use of classical mechanics. Quantum paradoxes do not exists because e.g the phenomenon such as two simultaneous antithetic state (e.g a cat dead and alive) are just intermediate QM calculations results that have no reality but are useful for calculations. Sadly QM are invaded by BS artists and "philosophers" which prefer fun magic to serious rigorous truths. Source: https://www.google.com/url?sa=t&source=web&rct=j&url=https:/...

[semi-extrinsic]

It is a travesty to put forward such unfounded claims, and then point to as source a paper by the great Anthony Leggett on the use of condensed matter systems to probe the quantum measurement problem.

What you are claiming is merely the proposition of "hidden variables" aka "local realism", a theory which has been thoroughly rejected by experimental measurements [1,2,3].

[1] https://www.nature.com/articles/nature15759

[2] https://doi.org/10.1103%2FPhysRevLett.115.250401

[3] https://doi.org/10.1103%2FPhysRevLett.115.250402

[krastanov]

I think it is rather misleading to state "40 years of reasearch" the way you are doing it. It was only in the late 90s that there was theoretical reasons to believe quantum error correction is feasible. And your goalpost of logical gates completely disregards the enormous (more than 6 orders of magnitude) exponential progress in the lifetime of physical qubits (see sibling comments for references). We still need a couple more orders of magnitude before things work out at the "logical gate layer", but it is dishonest to disregard the progress up to now.

[McTossOut]

There's a very intuitive inductive argument that places quantum computers ahead of classical computers.

Basically that quantum interactions are more fundamental to the universe than more terse ones, stochastic randomness or presence/absence.

If a computing device (in a universe) is built to compute using more fundamental substance (to that universe) it should stand to reason it is more efficient.

If you model a photon, does your model ever move as fast as the photon?

[The_rationalist]

I would like to understand what you mean but I can't, could you rephrase / exemplify?

"Basically that quantum interactions are more fundamental to the universe than more terse ones, stochastic randomness or presence/absence." What does more fundamental means? Presence, absence and randomness are included in the set of quantum interactions they are not of a different nature.

" If a computing device (in a universe) is built to compute using more fundamental substance (to that universe) it should stand to reason it is more efficient." What does fundamental substance mean? I don't understand this paragraph.

"If you model a photon, does your model ever move as fast as the photon?" My model does not move. If you meant that my mental visual simulation of a photon moving is slower than a photon moving, yes obviously, it's slowness and lack of accuracy is just a limitation of my brain. How is that related to quantum speedup?

Help me understanding you, I would really like to believe in quantum speedup but the explanation needs to be sound.

[McTossOut]

I'll reiterate that I was just hoping to share my intuition behind the subject but I'll try and point you in the right direction.

I mean that the relationship between Newtonian mechanics and Quantum mechanics is such that the matter described by Newtonian mechanics is composed of matter whose precise behavior is exclusively described by quantum mechanics, that is that underlying matter is fundamental to the macro behavior.

I'm by no means a physicist, but a formal treatment of this kind of relationship (and predicted consequences) is captured in Constructor Theory (as David Deutsch who may have been early in identifying this was able to formalize this in the much more precise language of physics)

Intuitively, if you took a whiffle ball (or pair of whiffle balls, or some other ensembleoof whiffle balls sufficient to represent a system's state) in your hands, and a little obstacle course representing, say, beam splitters, and with each in your hands somehow made these classical implements behave like photons, you would have little hope of doing this at light speed.

[The_rationalist]

Well thanks for the effort, that was interesting.

In general I have issues understanding many QM explanations as I disagree with all interpretations of QM except the statistical one. You might be interested to read this Nobel prize paper with test the limits of quantum mechanics and refute in a sound manner, common interpretations. https://www.google.com/url?sa=t&source=web&rct=j&url=https:/...