有谁知道什么是“量子计算"?是? [英] Does anyone know what "Quantum Computing" is?

问题描述

在物理学中，它具有使粒子在特定时间点以多种/平行动态状态存在的能力.在计算中，数据位同时等于1或0的能力是第三个值(如NULL [unknown]还是多个值)的能力?.该技术如何应用​​于:计算机处理器，编程，安全性等等.有人有没有建造出实用的量子计算机或开发出量子编程语言，例如，程序代码是动态变化的还是自主的?

In physics, its the ability for particles to exist in multiple/parallel dynamic states at a particular point in time. In computing, would it be the ability of a data bit to equal 1 or 0 at the same time, a third value like NULL[unknown] or multiple values?.. How can this technology be applied to: computer processors, programming, security, etc.?.. Has anyone built a practical quantum computer or developed a quantum programming language where, for example, the program code dynamically changes or is autonomous?

推荐答案

我已经完成了量子计算方面的研究，希望这是一个明智的答案.

I have done research in quantum computing, and here is what I hope is an informed answer.

人们通常说，量子计算机中的量子位可以以0和1的叠加"形式存在.这是正确的，但是比您可能首先想到的要微妙得多.即使使用具有随机性的经典计算机，也可以以0和1的叠加形式存在位，这意味着它以某种可能性为0，并且以某种可能性为1.就像当您掷骰子而不看结果或收到尚未阅读的电子邮件一样，您可以将其状态视为可能性的叠加.现在，这听起来像只是flim-flam，但是事实是，这种类型的叠加是一种并行性，并且使用它的算法可能比其他算法更快.这称为随机计算，您可以说该位处于概率状态，而不是叠加.

It is often said that qubits as you see them in a quantum computer can exist in a "superposition" of 0 and 1. This is true, but in a more subtle way than you might first guess. Even with a classical computer with randomness, a bit can exist in a superposition of 0 and 1, in the sense that it is 0 with some probability and 1 with some probability. Just as when you roll a die and don't look at the outcome, or receive e-mail that you haven't yet read, you can view its state as a superposition of the possibilities. Now, this may sound like just flim-flam, but the fact is that this type of superposition is a kind of parallelism and that algorithms that make use of it can be faster than other algorithms. It is called randomized computation, and instead of superposition you can say that the bit is in a probabilistic state.

那个量子位和一个量子位之间的区别在于，一个量子位可以具有大量具有更多属性的可能叠加.普通位的概率状态集是一个线段，因为所有概率均为0或1.量子位的状态集是一个三维3D球.现在，概率位字符串比单独的概率位更加复杂和有趣，对于量子位字符串也是如此.如果您可以像这样制作qubit，那么实际上某些计算任务不会比以前更容易，就像随机算法不能解决所有问题一样.但是某些计算问题(例如因数分解)具有新的量子算法，该算法比任何已知的经典算法都快得多.这与时钟速度或摩尔定律无关，因为第一个有用的量子位可能相当慢且昂贵.这只是某种并行计算，就像做出随机选择的算法只是在狭义上并行进行所有选择一样.但这是关于类固醇的随机算法"；这是外人最喜欢的摘要.

The difference between that and a qubit is that a qubit can have a fat set of possible superpositions with more properties. The set of probabilistic states of an ordinary bit is a line segment, because all there is a probability of 0 or 1. The set of states of a qubit is a round 3-dimensional ball. Now, probabilistic bit strings are more complicated and more interesting than just individual probabilistic bits, and the same is true of strings of qubits. If you can make qubits like this, then actually some computational tasks wouldn't be any easier than before, just as randomized algorithms don't help with all problems. But some computational problems, for example factoring numbers, have new quantum algorithms that are much faster than any known classical algorithm. It is not a matter of clock speed or Moore's law, because the first useful qubits could be fairly slow and expensive. It is only sort-of parallel computation, just as an algorithm that makes random choices is only in weak sense making all choices in parallel. But it is "randomized algorithms on steroids"; that's my favorite summary for outsiders.

现在是个坏消息.为了使经典片段重叠，对您来说，这是一个秘密选择，这是一个随机的选择.一旦您看了一眼翻动的硬币，硬币肯定会塌陷"到正面或反面.该量子位与一个量子位之间的区别在于，要使一个量子位作为一个整体工作，它的状态必须对物理宇宙的其余部分(而不只是对您而言)是秘密的.它必须是从空气中，附近的原子等中获得的秘密.另一方面，对于量子比特对量子计算机有用的东西，必须有一种在保持其状态秘密的同时进行操纵的方法.否则，其量子随机性或量子相干性将受到破坏.完全制作qubit并不容易，但这是常规完成的.要制作可以用量子门操纵的量子位，而又不向物理环境揭示量子位中的内容，是非常困难的.

Now the bad news. In order for a classical bit to be in a superposition, it has be a random choice that is secret from you. Once you look a flipped coin, the coin "collapses" to either heads for sure or tails for sure. The difference between that and a qubit is that in order for a qubit to work as one, its state has to be secret from the rest of the physical universe, not just from you. It has to be secret from wisps of air, from nearby atoms, etc. On the other hand, for qubits to be useful for a quantum computer, there has to be a way to manipulate them while keeping their state a secret. Otherwise its quantum randomness or quantum coherence is wrecked. Making qubits at all isn't easy, but it is done routinely. Making qubits that you can manipulate with quantum gates, without revealing what is in them to the physical environment, is incredibly difficult.

除了非常有限的玩具演示，人们不知道该怎么做.但是，如果他们能够做得足够好以制造量子计算机，那么对于这些​​计算机，一些困难的计算问题将容易得多.其他人根本不会轻松，而且关于哪些可以加速以及提高多少尚不十分清楚.它肯定会对密码学产生各种影响；它会破坏公钥密码术的广泛使用形式.但是已经提出了其他种类的公钥密码学，可能还可以.此外，量子计算与看起来非常安全的量子密钥分发技术有关，秘密密钥密码术几乎肯定仍将是相当安全的.

People don't know how to do that except in very limited toy demonstrations. But if they could do it well enough to make quantum computers, then some hard computational problems would be much easier for these computers. Others wouldn't be easier at all, and great deal is unknown about which ones can be accelerated and by how much. It would definitely have various effects on cryptography; it would break the widely used forms of public-key cryptography. But other kinds of public-key cryptography have been proposed that could be okay. Moreover quantum computing is related to the quantum key distribution technique which looks very safe, and secret-key cryptography would almost certainly still be fairly safe.

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