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Chinese Researchers Achieve Quantum Entanglement Record

scientificamerican.com

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Re: Chinese Researchers Achieve Quantum Entanglement Record

#131

Post by kart23 »

reaperducer wrote: post #8
ssdd wrote: post #6

Earlier quoted context omitted.

That's great. Now next thing that needs to be solved is to make this tech available for general public use just like computers are these days. Problems that are waiting to be solved by it are very large and of huge impact.

Problems that are waiting to be solved by it are very large and of huge impact I know virtually nothing about quantum computing, so can you give some examples? Whenever I've asked anyone who seemed to know anything about the field, all they can come up with is weather forecasting and simulating nuclear explosions. Not exactly "general use," as you put it. In the back of my mind, I know that quantum computing is a big…

Doesn't basically all encryption become meaningless with quantum computers? Remember how they always said 'it would take a billion years to crack this encryption with a computer'? Well soon we are going to have computers that don't play by the rules.

Re: Chinese Researchers Achieve Quantum Entanglement Record

#132

Post by donutte »

breadAndWater wrote: post #130
donutte wrote: post #127

Earlier quoted context omitted.

I’m not sure I follow your argument, but if I understand you right, I don’t believe what you’re quoting is relevant. From the article you are (I think?) criticizing: We measure a Bell signal S of 2.0732 ± 0.0003, exceeding the maximum value |S| = 2 for a classical system by 244 standard deviations. In the experiment, we deterministically generate the entangled state, and measure both qubits in a single-shot manner, c…

Uh, wow, at no point have I made the claim that an electrical circuit is not a quantum system. Nor have I claimed that they are incapable of simulating quantum phenomena. Quite the very opposite. What I did clearly state, and insist as quite relevant, is that entanglement and double slit experiments are hocus pocus and irrelevant distractions. In fact, I stated that this experiment says basically nothing because it m…

The experiment demonstrates quantum entanglement. I gather you don’t believe this. So how about this: I don’t believe you.

I don’t believe that you could, even theoretically, produce the data from a loophole-free Bell test without invoking superdeterminism, superluminality, or quantum entanglement.

Can you describe how this would be theoretically possible?

Re: Chinese Researchers Achieve Quantum Entanglement Record

#133

Post by mirekrusin »

bscphil wrote: post #111
deepGem wrote: post #23

Earlier quoted context omitted.

So the number of raw qubits are in the order of a million for large prime factorization or to make Shor's algorithm a reality. This is because the physical qubits are highly unstable and prone to errors. The error correction methodologies will result in a fault-tolerant logical qubit. Depending on the error correction algorithm, the ratio of logical: data/physical qubit is 1:1000 at the minimum. You need 4000 logical…

This is probably a dumb question, but could you spread out the error correction in time? I know it's hard to create very large entangled systems, so would it be possible/easier to do the calculation with 4000 real qubits 1000 times and use the repetition for error correction? (Checking for correct factorization is easy, after all.)

Calculation on quantum state is already spread in time. Each time you calculate something you basically take snapshot of the state. Then you do it again. After many trials patterns emerge - that’s when you start reading your answer - which is always probabilistic.

Re: Chinese Researchers Achieve Quantum Entanglement Record

#134

Post by oblio »

z3phyr wrote: post #128
Erlich_Bachman wrote: post #97

Earlier quoted context omitted.

They haven't seen counterexamples because there are virtually none. If what you said was correct wouldn't there be many examples of big bodies of code written in a language like C? (And you can't say "linux kernel" - low-level code needs to be written in a low-level language, in order to communicate with the lower levels like hardware and controllers and such. There is a practical reason to write that in C.) > becaus…

The trend is to make solving problems easier for the untrained; giving the heavy lifting to the machines, making the machines slower for the actual task at hand. Nobody is actually targeting the experts who will love to have more power over safety

This won't be popular here, but maybe the economics work against the experts. If most problems out there can be solved with mediocre interchangeable cogs much faster than with the available pool of experts, the cogs will win long term.

So far, reality seems to confirm my intuition.

Re: Chinese Researchers Achieve Quantum Entanglement Record

#135

Post by yadaeno »

jblow wrote: post #15
ssdd wrote: post #6

Earlier quoted context omitted.

That's great. Now next thing that needs to be solved is to make this tech available for general public use just like computers are these days. Problems that are waiting to be solved by it are very large and of huge impact.

We all have these things in our pockets that are massive supercomputers by the standards of my college days. And we all use them just to rant at each other about political things that we in reality are totally misinformed about ... and otherwise just waste our lives. I am not sure why quantum computing is supposed to change this. Even software that is supposed to be useful is so terribly slow. Computers are between 2…

Moores law says that programming is allowed to get half as efficient every year!

Re: Chinese Researchers Achieve Quantum Entanglement Record

#136

Post by z3phyr »

oblio wrote: post #134
z3phyr wrote: post #128

Earlier quoted context omitted.

The trend is to make solving problems easier for the untrained; giving the heavy lifting to the machines, making the machines slower for the actual task at hand. Nobody is actually targeting the experts who will love to have more power over safety

This won't be popular here, but maybe the economics work against the experts. If most problems out there can be solved with mediocre interchangeable cogs much faster than with the available pool of experts, the cogs will win long term. So far, reality seems to confirm my intuition.

I do not disagree with you here. In the economic (real) world, "better" is the enemy of "good enough". In the hacker world, the craft is appreciated more.

Re: Chinese Researchers Achieve Quantum Entanglement Record

#137

Post by foxes »

moefh wrote: post #89
foxes wrote: post #18

Earlier quoted context omitted.

There are already lots of 'practical' applications in the literature. A famous one is Shor's factorisation algorithm. But there are others - everything from doing pagerank to simulating other quantum systems. Many classical algorithms, which run in ~O(poly(n)) can have an 'equivalent' quantum algorithm in ~O(log(n)) - an exponential speedup. There is still debate as to how the complexity class of problems which are e…

> Its suspected P lies entirely within BQP. It's actually known that BQP contains P[1]. It also contains BPP. What's not known is the relationship between BQP and NP (most experts suspect there's no containment in either direction). [1] See this for an easy proof: https://people.eecs.berkeley.edu/~vazirani/f04quantum/notes/...

Yes sorry you are right. I found this nice example of Grover's algorithm [0].

[0] http://davidbkemp.github.io/animated-qubits/grover.html

Re: Chinese Researchers Achieve Quantum Entanglement Record

#138

Post by hrygolis »

moefh wrote: post #89
foxes wrote: post #18

Earlier quoted context omitted.

There are already lots of 'practical' applications in the literature. A famous one is Shor's factorisation algorithm. But there are others - everything from doing pagerank to simulating other quantum systems. Many classical algorithms, which run in ~O(poly(n)) can have an 'equivalent' quantum algorithm in ~O(log(n)) - an exponential speedup. There is still debate as to how the complexity class of problems which are e…

> Its suspected P lies entirely within BQP. It's actually known that BQP contains P[1]. It also contains BPP. What's not known is the relationship between BQP and NP (most experts suspect there's no containment in either direction). [1] See this for an easy proof: https://people.eecs.berkeley.edu/~vazirani/f04quantum/notes/...

https://www.quantamagazine.org/finally-a-problem-that-only-q...

Re: Chinese Researchers Achieve Quantum Entanglement Record

#139

Post by wiz21c »

deepGem wrote: post #23
bscphil wrote: post #19

Earlier quoted context omitted.

What's the size needed for cracking large-primes based encryption? If not at 100 qubits, what are some useful calculations that we can do at that size?

So the number of raw qubits are in the order of a million for large prime factorization or to make Shor's algorithm a reality. This is because the physical qubits are highly unstable and prone to errors. The error correction methodologies will result in a fault-tolerant logical qubit. Depending on the error correction algorithm, the ratio of logical: data/physical qubit is 1:1000 at the minimum. You need 4000 logical…

>>> qubits are highly unstable

newbie question : are they naturally instable (so we won't fix that) or is it just because we don't master them well enough right now (and we'll fix them "soon") ?

Re: Chinese Researchers Achieve Quantum Entanglement Record

#140

Post by deepGem »

wiz21c wrote: post #139
deepGem wrote: post #23

Earlier quoted context omitted.

So the number of raw qubits are in the order of a million for large prime factorization or to make Shor's algorithm a reality. This is because the physical qubits are highly unstable and prone to errors. The error correction methodologies will result in a fault-tolerant logical qubit. Depending on the error correction algorithm, the ratio of logical: data/physical qubit is 1:1000 at the minimum. You need 4000 logical…

>>> qubits are highly unstable newbie question : are they naturally instable (so we won't fix that) or is it just because we don't master them well enough right now (and we'll fix them "soon") ?

It's the former. They can be made stable at super conducting temperatures but not completely. There will always be errors. From what I can understand you cant fully eliminate the errors. I donno may be some new superconducting temp might make them stable but that's a wild guess.
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