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I'm Scott Aaronson, quantum computing/computational complexity researcher. AMA

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Re: I'm Scott Aaronson, quantum computing/computational complexity researcher. AMA

#301

Post by i-blis »

ScottAaronson wrote: post #266
ahelwer wrote: post #185

Hey, Scott! Love your book, Quantum Computing Since Democritus. There is one section which confused me, in the Quantum chapter ( https://www.scottaaronson.com/democritus/lec9.html ). I have two questions: 1) You say applying the unitary operation is the quantum analogue of "taking a coin and flipping it" - what do you mean by this? Could we think of, for example, a pair of slits as applying this transformation on a p…

1) Yes, a unitary transformation like the Hadamard gate maps the state |0> to |0>+|1>, while mapping |1> to |0>-|1>. In either case, if you then just measured immediately in the {|0>,|1>} basis without doing anything else, you'd see |0> or |1> with equal probabilities, so it would have the effect of a coin flip. But of course, in other cases---e.g., if you measured in a different basis, or if you applied the Hadamard…

The cleanest explanation I read of information / state linearity properties of quantum operators. Thanks! (Working through Brian Hall's Quantum Theory for Mathematicians and Frederic Schuller's course at the moment, both highly recommended).

Re: I'm Scott Aaronson, quantum computing/computational complexity researcher. AMA

#302

Post by thecrazyone »

stcredzero wrote: post #190
ScottAaronson wrote: post #140

Earlier quoted context omitted.

A quantum computer is a device that exploits constructive and destructive interference among exponentially many amplitudes , which are numbers that are closely related to probabilities but can be positive, negative, or even complex. If you feel that sentence wasn't clear enough, and it would take at least a few more paragraphs to flesh it out ... well, duh, what did you expect? :-D For a SLIGHTLY longer account, see…

Here's my attempt at a two sentence over-over-over simplification that at least gets people away from the "magic bit-sting that contains your answer." (It also harkens back to an old Einstein quote, so may be attractive to science writers.) Quantum computing is a technique that lets you sample a problem's answer-space using "loaded dice," such that the problem's correct answers correspond with probability spikes in y…

Wow, that was nice and succinct.

Re: I'm Scott Aaronson, quantum computing/computational complexity researcher. AMA

#303

Post by thecupisblue »

ScottAaronson wrote: post #295
thecupisblue wrote: post #25

Hi! So, what do you do when you're not flipping qubits around? Got any cool stories you wanna share?

When I'm not flipping qubits around, I eat, sleep, blog, answer emails, play with my two kids, get depressed reading the news about US politics, and then get even more depressed reading people saying mean things about me and my nerdy friends on Twitter and Reddit.

Awwww man! That sucks, but screw those naysayers. They ain't the ones running point on quantum computing.

(I don't really have much to ask you since anything I could comprehend is easily googlable and I don't wanna waste ur time. Just wanna say keep up the good work and thanks!)

Re: I'm Scott Aaronson, quantum computing/computational complexity researcher. AMA

#305

Post by ScottAaronson »

AgentME wrote: post #191
martin1975 wrote: post #99

Earlier quoted context omitted.

Am I hearing this right, you think the whole multiverse concept is... meta-physics at best?

I think he was saying about whether you should morally care about the other branches counted as meta-physics.

Yup.

Re: I'm Scott Aaronson, quantum computing/computational complexity researcher. AMA

#306

Post by ScottAaronson »

SurfaceCode wrote: post #304

Scott, Do you think it's a good idea that all the teams working on quantum computing have put their money on the surface code? What are your thoughts? Do you believe that we are putting all our eggs in one basket?

I'm not an expert on this, but I think the surface code is so popular because it's 2-dimensionally local and has great parameters and speed of error correction. But people certainly work on other codes too, and if someone invents something that's unequivocally better than the surface code---or better for what the experimentalists are building now---I guarantee you they'll take notice! They don't always care about finer points of complexity theory, but this they do care about.

Re: I'm Scott Aaronson, quantum computing/computational complexity researcher. AMA

#307

Post by ScottAaronson »

YeGoblynQueenne wrote: post #262
ScottAaronson wrote: post #231

Earlier quoted context omitted.

You should probably wait for an AMA with someone who's actually an expert in AI, and ask them this question. Since you asked me, though, I did a quick Google search and found the following paper: https://arxiv.org/pdf/1711.09667.pdf where indeed they use machine learning to induce the rules of chess from a large number of played games (and then learn to play better than any human). It doesn't surprise me at all that…

>> where indeed they use machine learning to induce the rules of chess from a large number of played games (and then learn to play better than any human). They didn't induce the rules of chess! What they did was learn an evaluation function for chess moves, from scratch, i.e. without giving it the rules or any hand-crafted features. So they learned a classifier for good/bad board states, which was later used in an al…

Aha, thanks for that extremely useful clarification! I was also confused from the abstract and intro about exactly what the inputs and outputs were. Yes, the clear impression was created that they learned the rules---in the sense that they could then generate moves that would (usually? almost always?) obey the rules---when it sounds like really they just learned an evaluation function that encodes lots of implicit knowledge about the rules, of course, but that still requires a piece of code that knows the rules explicitly as a "guardrail" when generating moves.

Since you obviously know this subject, what are the best current results in the direction of inducing the rules of chess from played games?

Re: I'm Scott Aaronson, quantum computing/computational complexity researcher. AMA

#308

Post by ScottAaronson »

gb22 wrote: post #161

Hi Scott 1. What do you think is the potential for emergence of a third computing model, apart from classical and quantum, which is sufficiently different in its fundamental computing paradigm from these? Do you believe biological substrates offer opportunity for computing which classical/QC cannot replicate? 2. If we achieve quantum supremacy, who do you think will be the biggest winners and losers, in terms of prof…

1. Quantum computing is the most powerful model of computation we have based on currently known physics---in the sense that anything more powerful would need to be based on new physics. From the standpoint of theoretical computer science, a biological computer is "just" a different way to implement classical computation, typically with very slow speed but very enormous parallelism. It might someday have practical advantages, but unless we're totally mistaken about biology, it's not going to solve any problems efficiently that are outside BPP (i.e., classical probabilistic polynomial time). For that you need a quantum computer.

2. Yes, if quantum computing is successful, I imagine that might be good for the careers of many of the people involved in quantum computing.

3. Regarding D-Wave, there's this weird tendency to get fixated on words and definitions (but is it "really" QC or "really" analog?) even after you've explained the reality of the situation. See https://news.ycombinator.com/item?id=17426023 for my current summary.

Again, I'm skeptical that analog computers will ever be able to solve any problems outside BPP---for that I think you need a QC. (I.e., if not for quantum mechanics, I would have believed in the Extended Church-Turing Thesis. :-) ) Whether analog computers will ever again compete with digital ones on the constant factors, leaving aside the asymptotics, for problems that people actually care about, is a harder and more complicated question to which I don't know the answer.

Re: I'm Scott Aaronson, quantum computing/computational complexity researcher. AMA

#309

Post by ejanus »

stcredzero wrote: post #190
ScottAaronson wrote: post #140

Earlier quoted context omitted.

A quantum computer is a device that exploits constructive and destructive interference among exponentially many amplitudes , which are numbers that are closely related to probabilities but can be positive, negative, or even complex. If you feel that sentence wasn't clear enough, and it would take at least a few more paragraphs to flesh it out ... well, duh, what did you expect? :-D For a SLIGHTLY longer account, see…

Here's my attempt at a two sentence over-over-over simplification that at least gets people away from the "magic bit-sting that contains your answer." (It also harkens back to an old Einstein quote, so may be attractive to science writers.) Quantum computing is a technique that lets you sample a problem's answer-space using "loaded dice," such that the problem's correct answers correspond with probability spikes in y…

"Loaded dice ", I have not heard that before... Is it same as Biased dice

Re: I'm Scott Aaronson, quantum computing/computational complexity researcher. AMA

#310

Post by [deleted] »

AgentME wrote: post #237
martin1975 wrote: post #196

Earlier quoted context omitted.

That word 'testable', is very loaded. :) But I get what you mean. Are there things that we can't test that do exist?

>Are there things that we can't test that do exist? There's many reasons to believe that objects that exit our light cone continue to exist after they do, even though they could never have any future interaction with us to confirm that. (Say a spaceship leaves Earth at near the speed of light in a straight line, and then enough time passes that the space between the ship and Earth is expanding so fast that the spaces…

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