The Chinese Academy of Sciences slaps Google in the face: ordinary computers catch up with quantum superiority, and can solve calculations that would have taken 10,000 years in a few hours...

衡宇 发自 凹非寺
量子位 | 公众号 QbitAI

Google quantum computing,Claimed to be there200Get ordinary supercomputing in seconds10000tasks completed in the year.

没想到,这个“量子优越性”Now broken by researchers at the Institute of Theoretical Physics, Chinese Academy of Sciences：

They use normal processors,Completed in a few hours what was originally thought to take1万年的计算,And think that the current quantum computer can be completely surpassed.

ACM计算奖得主Scott Aaronsonalso agree with this conclusion：

我认为他们是对的,If there is a powerful enough supercomputer,They can simulate this task in seconds.

最近SciencePublished an article on the matter,Let's see what happened.

无法超越？Optimized for you to see

Zhang Pan's team at the Institute of Theoretical Physics, Chinese Academy of Sciences,发表了一篇名为《Sycamore 量子优势电路采样问题的求解》的论文,Demonstrated beating Google's quantum computerSycamore的全过程.

针对谷歌“量子优越性”的任务,A new simulation method is proposed in this paper,That is, the classical algorithmTensor network methods.

To say how good it is,Just use a lotGPU并行计算.

利用512个GPU的计算集群,The team counted9of trillions of strings of numbers100Thousands of output modes（即53量子比特、20Cyclic quantum circuit sampling）,This calculation process is expensive15个小时.

If this algorithm is used on a supercomputer,几十秒can accomplish the same task.

If this task is givenSycamore做,Approx200秒内;超级计算机则需要10000年才能完成（Google says so）.

△Google quantum computing chip,Just the size of a postage stamp

The team also has a point of view,那就是和Sycamore一样,There is no need to be overly precise.

The team used tensors to represent the relationship between qubit properties,把Sycamore量子比特的相互作用描述为3D张量网络.

所以,他们在3Don the tensor network“drill holes”,Cut some connections to simplify the relationship,Reduce computational complexity,Trade accuracy for speed.This method of shrinking tensor networks,Make it possible to simulate quantum chips.

数据证明,in the process of completing the task,The calculation speed has been improved256倍.

且保真度保持在0.37%,高于Sycamore的0.2%.

All kinds of data are in front of you,“量子优越性”Suddenly it doesn't smell so good.

“量子优越性”擂台,搭起来

面对这个结果,谷歌量子AI首席研究员Sergio BoixoRespond to think,It's just a brief overtake on the track,The advantage doesn't last long.

From the beginning of the quantum computing era,Google has never denied that the classic algorithm will continue to improve and improve.

不过,谷歌也表示：

We believe that this classical algorithm cannot exist 2022 Years later to keep up with quantum circuits.

毕竟Sycamore诞生时,A supercomputer can only be daunted by the tasks it performs.

Create a quantum computer,is to perform those calculations“淹没”normal computer tasks.

对于量子计算机来说,A potential solution to all tasks can be seen as quantum waves sloshing between qubits at the same time.

These quantum waves interfere with each other,Wrong answers cancel each other out,The correct output will be“弹”出来.

换句说话,This interference allows quantum computers to split up the massive amounts of data that need to be calculated.

拿Sycamore来说,It sets the qubit to 0、1或者0和1的任意组合,This allows it to handle large amounts of input at the same time.

Sycamore是一台53量子比特的量子计算机,Its quantum circuits are tiny resonant circuits made of superconducting metals,Can encode from0到2⁵³（约9万亿）any number in between,It is even possible to encode all numbers at once.

谷歌表示,Sycamore可以打败IBMdeveloped supercomputerSummit.Summit拥有9216个CPU和27648个GPU.

IBMImmediately give a rebuttal,It takes time to say Google's so-called supercomputer for the same task“10000年”,Just on a specific algorithm.

Once the algorithm is optimized,只需约2.5天,Summitdo the same task.

关于“量子优越性”,业界、The academic debate has never stopped.

This paper by Zhang Pan's team,It is proved by example“量子优越性”At this stage, it can still be defeated by ordinary computers.

One More Thing

The research results of Zhang Pan's team highlight the shortcomings of quantum computers compared with traditional computers,This pair is more advanced“量子优越性”Experiments put forward higher requirements.

Zhang Pan proposed,Some practical applications should be found to demonstrate the advantages of quantum circuits.

当然,Ordinary computers beat“量子优越性”Does not mean the demise of quantum circuits.

Even compared to supercomputers,SycamoreThe operating steps and required power are much less.Even Zhang Pan said it himself,如果SycamoreA little higher fidelity,Team simulations are no match~

参考文章：
[1]https://www.science.org/content/article/ordinary-computers-can-beat-google-s-quantum-computer-after-all?s=31
[2]https://www.science.org/doi/10.1126/science.365.6460.1364
[3]https://arxiv.org/pdf/2111.03011.pdf

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