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Scott’s Supreme Quantum Supremacy FAQ

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Re: Scott’s Supreme Quantum Supremacy FAQ

#101

Post by jessriedel »

sanxiyn wrote: post #88
jessriedel wrote: post #82

Earlier quoted context omitted.

I don't understand. Factoring composite numbers into their primes is definitely a predicted use for QC in the future. Are you just saying the architecture of the machine powerful enough to do that is still uncertain?

I think it is analogous to fusion. Fusion definitely works (the Sun and hydrogen bomb) and power generation is a predicted use of fusion in the future. That doesn't mean we have known path to fusion for power generation. To extend the analogy, quantum supremacy is like fusion for neutron source. There are commercial fusion devices to be used as neutron source.

Everything hinges on what you mean by the very vague term "known path". Every technology more than a few years out requires currently unknown problems to be solved. Even, say, the next generation of processors will require many engineer-years to solve currently unsolved problems, and the generation after that is pretty opaque right now. Still, we can have confidence that they will be developed.

Re: Scott’s Supreme Quantum Supremacy FAQ

#102

Post by ClintEhrlich »

klipt wrote: post #91
ClintEhrlich wrote: post #87

Earlier quoted context omitted.

On second reading, I have but one trivial gripe: "Enormity" implies moral reprobation, so it's a poor way of describing the significance of a computational discovery.

Isn't it just Enormous : enormity :: huge : hugeness?

Not quite.

Enormous : enormousness :: huge : hugeness.

Enormity = Immense scale of evil (e.g., the "enormity of the holocaust")

Re: Scott’s Supreme Quantum Supremacy FAQ

#103

Post by erichocean »

> It’s like, if you believed that useful air travel was fundamentally impossible

Uh, there are birds. Literally everyone thought useful air travel was possible, and not only possible, but so easy that a Darwinian process was able to produce it, not once, but literally thousands of times, in thousands of ways.

----

But looking at the actual "experiment", I don't count that as computation in any meaningful sense, and morally equivalent to the following:

Set up a digital camera and point it at a scene. Take a picture. Now take millions of additional pictures, without moving the camera.

Measure the values at each pixel. See how they correspond to "amplitudes"? That's our computation. Article (smugly): How about you simulate (render) the scene using an actual computer? Measure the amplitudes of the resulting millions of images. OMG, that took you so long!!! Loser.

Are we being punk'd here?

The digital camera is the quantum computer. The "scene" is the random initial state C. The scene is then translated into a renderable scene for the classical computing version, and rendered with an unbiased physically based renderer, which produces the same result.

I fail to see how any of this is even remotely exciting, much less interesting. A camera is not a computer, no matter how many measurements you make with it, nor how "random" the scene you are taking pictures of is.

And yes, simulating reality takes more cycles than just measuring whatever happened with a camera. Photos are "faster" to get than the equivalently rendered scene—news at 11!

Again: Are we being punk'd here?

Re: Scott’s Supreme Quantum Supremacy FAQ

#105

Post by khawkins »

yters wrote: post #92

Most major breakthroughs were pretty low tech in origin, and the high tech was all about optimizing the idea. I think we get fundamental research backwards nowadays.

At the very least, we shouldn't be comparing quantum computing to air flight. The Wright brothers were basically hobbyists, incomparable to the global leading technology corporations in the history of human civilization.

This seems more comparable to the moon landing or LHC Higgs-Boson discovery. Challenging to pull off once, and the next steps seem to increase exponentially in man-power and cost.

Re: Scott’s Supreme Quantum Supremacy FAQ

#106

Post by alanbernstein »

ClintEhrlich wrote: post #102
klipt wrote: post #91

Earlier quoted context omitted.

Isn't it just Enormous : enormity :: huge : hugeness?

Not quite. Enormous : enormousness :: huge : hugeness. Enormity = Immense scale of evil (e.g., the "enormity of the holocaust")

Thanks for the enlightening nitpick, this is one of those terrible/terrific things about English that I love/hate.

Re: Scott’s Supreme Quantum Supremacy FAQ

#107

Post by cma »

sanxiyn wrote: post #69
gowld wrote: post #58

Earlier quoted context omitted.

What are the theoretical models for the energy cost of computing on a qubit? I'll be excited for QC when there is known way (even with some handwaving and future-tech plans) to compute a non-trivial result for a reasonable sum, such as "crack someone's private RSA key for under $10M of compute cost"

This depends on your definition of "trivial". But if we restrict it to factoring, no, there is no known path to QC factoring at the moment, none at all.

Factoring has already been done. For the size number factored it did use much more energy than it would have taken on a classical device, but it did utilize quantum effects/Shor’s algorithm:

https://en.m.wikipedia.org/wiki/Integer_factorization_record...

Re: Scott’s Supreme Quantum Supremacy FAQ

#108

Post by andrewflnr »

ClintEhrlich wrote: post #102
klipt wrote: post #91

Earlier quoted context omitted.

Isn't it just Enormous : enormity :: huge : hugeness?

Not quite. Enormous : enormousness :: huge : hugeness. Enormity = Immense scale of evil (e.g., the "enormity of the holocaust")

As a native English speaker, I can't say I've found this to be the case. "Enormity" does tend to be used for dramatic effect, most often on moral issues, but I don't think that makes Scott wrong to use it here.

I don't know if I've seen "enormousness" before this thread.

Re: Scott’s Supreme Quantum Supremacy FAQ

#109

Post by ramraj07 »

gtirloni wrote: post #104

I've read almost all comments here and, although I've grown up with lots of technology, this is the kind of stuff that will turn me into my parents/grandparents. It's like when I was teaching them how to operate the VCR years ago.

Your analogy explains itself away - maybe you knew how everything inside a vcr worked but I didn't, I just knew what the buttons did and how to clean the head. I'm sure we will figure our way around these quantum knobs as well!

(Seriously though, why the hell did those vcrs have such a large green board??)

Re: Scott’s Supreme Quantum Supremacy FAQ

#110

Post by tagrun »

3PS wrote: post #32
nexuist wrote: post #2

Preface: I know nothing about quantum computing. What exactly is a qubit? I'm not asking what does it mean, because I know there's superpositions and all that jazz, but as in...like, in an electronic circuit, what is a qubit? Is it made out of logic gates? Which ones? If we can make one qubit, can't we just make a bunch of them by copy and pasting circuits similar to how we used vacuum tubes in the 60s and 70s? How c…

Short answer, a qubit is a unit vector in a 2D complex Hilbert space. Now, that doesn't actually say much about why we care or how they're useful. In practical terms, you can think of qubits as complex unit vectors along two axes, with one axis corresponding to |0⟩ (the zero qubit) and one axis corresponding to |1⟩, or the one qubit. So for example, you could have a qubit called |+⟩, which is just shorthand for (|0⟩…

This is like saying that voltage is a scalar real number, which explains nothing about the physics of electromagnetism, and in my opinion is probably the worst way to explain physics of anything. It especially tells nothing useful given the question is about the stuff that a qubit is made of (which is different from "how do you mathematically represent an ideal qubit on paper?").

And going beyond that, as Peres puts it, "Quantum phenomena do not occur in a Hilbert space. They occur in a laboratory."

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