“我们发现这非常有意思——在两个进行通讯的人之间，不需要任何东西通过就可以沟通的可能”，阿哈罗诺夫说，“并且，我们想看看我们是否能更好地理解它。”

另一篇解释的文章说“”To be more precise, their analysis argues information could be transferred between two points without an exchange of particles”

“更确切地说，他们的分析认为，信息可以在两个位置之间传递，而不必交换粒子”

https://www.sciencealert.com/schrodinger-s-cat-gets-a-cheshire-grin-in-a-mind-bending-quantum-physics-analysis

Elementary particles part ways with their properties

基本粒子和其属性可以分离

11月8日 DECEMBER 8, 2020 FEATURE

https://phys.org/news/2020-12-elementary-particles-ways-properties.html

作者：Anna Demming , Phys.org

译者：康华岳

A particle separating from its properties may help explain the paradox of a mirror’s impact on a particle that never comes into contact with it in counterfactual quantum communication. Credit: Physical Review Letters.

与自己的属性分离的粒子，或许可以帮助解释这样的悖论：在与事实相悖的量子通讯中，一面镜子即便从未与一个粒子接触，也会对这个粒子产生影响。

"Spooky action at a distance," Einstein's summation of quantum physics, has been a criticism of quantum mechanics since the field emerged. So far, descriptions of entangled particles to explain their apparently faster-than-light responses, and even explanations for the phase shifts induced by an electromagnetic field in regions where it is zero—the "Aharonov-Bohm" effect—have mostly addressed these concerns. However, recent theoretical and experimental demonstrations of a "counterfactual" quantum communication protocol have proved difficult to explain in terms of physical cause and effect. In this kind of quantum communication, observers on either side of a "transmission channel" exchange information without any particle passing between them—spooky indeed.

“远处诡异的行为”是爱因斯坦对量子力学的总结，量子力学的这个特点从它开始出现就受到批评。迄今为止，人们对纠缠的粒子的描述，用来解释它们貌似超光速的反应，甚至人们对，电磁场即便为零的区域里，电磁场还能诱发相态转变的“阿哈罗诺夫－玻姆”效应的描述（带电粒子在电磁场为零的区域仍然会受到电磁势的作用）——最主要的就是为了解决这些困惑。然而，近期，对一种“与事实相悖”的量子通讯协议的理论和实验层面的演示，都表明，对该种实验而言，用物理层面的因果作用来解释是非常困难的。在这类量子通讯中，“传递渠道”两边的观察者可以无需在两者间有任何粒子通过就能实现信息交换——这确实很诡异。

Now, Yakir Aharonov, Professor at Tel Aviv University in Israel and Chapman University in the U.S., and Daniel Rohrlich, Professor at Ben-Gurion University of the Negev in Israel, have taken a closer look at this so-called counterfactual quantum communication protocol in terms of conserved particle properties. Their analysis provides an explanation of counterfactual quantum communication that does not call upon "spooky action at a distance," but instead implies that the particle and one of its conserved properties—modular angular momentum—part ways.

现在，以色列特拉维夫大学以及美国查普曼大学的教授亚基尔·阿哈罗诺夫（Yakir Aharonov），

以及以色列内盖夫本古里安大学的教授美国丹尼尔·罗利希（Daniel Rohrlich），对这个所谓的“与事实相悖”的量子通讯协议，在守恒的粒子属性方面（conserved particle properties），进行了更为仔细的研究。他们的分析，提供了一种对反事实量子通讯的解释，而这种解释无需借助“远处的诡异行为”，相反，这个解释暗示，粒子和其守恒的属性中的一种——模角动量可以分开。

The spooky quantum protocol

诡异的量子协议

The counterfactual quantum communication protocol reported in 2013 arose through theoretical studies of two observers—good old Alice and Bob—liaising via particles along a transmission channel, as reported by Hatim Salih, Zheng Hong Li, Mohammad Al-Amri and Muhammad Suhail Zubairy (then at the National Center for Mathematics and Physics in Saudi Arabia and Texas A&M University in the U.S.).

与事实相悖的量子通讯方案在2013年就在理论研究中被报道了。这是针对两个观察者的理论研究，老熟人Alice和Bob，他们通过一个传送通道进行联络，这个研究报告的作者是Hatim Salih, Zheng Hong Li, Mohammad Al-Amri, Muhammad Suhail Zubairy（当时在沙特阿拉伯的国家数学与物理中心和美国德克萨斯农工大学）。

"They got very interested in the fact that these massive particles, which would be signals, could be stopped and blocked," explains Rohrlich. In their analysis, Salih and co-authors showed that when there were two partially blocking barriers in the channel, Alice was able to identify whether or not Bob had closed his end of the channel with a reflecting mirror or left it open, even though the wavefunction as it evolved under the conditions set could not enter Bob's end of the channel.

“他们对这一事实非常感兴趣，即，这些大的粒子，本可以作为信号，但却可以被停下来并被阻拦下来，”罗利希解释道。在他们的分析中，Salih和合作者表明，当通道中存在两个部分地阻塞的障碍时候，Alice用一个反射镜，也还能够识别出Bob是否关闭了Bod所在的通道的那一端还是保持在打开状态，即使在这些状况下随时间演化的波函数不能进入通道中Bob的一端。

"We found it extremely interesting—the possibility of communication without anything passing between the two people who communicate with each other," says Aharonov. "And we wanted to see if we can understand it better."

“我们发现这非常有意思——在两个进行通讯的人之间，不需要任何东西通过就可以沟通的可能”，阿哈罗诺夫说，“并且，我们想看看我们是否能更好地理解它。”

A conservative approach

一个守恒的方法

In fact, Aharonov already has a legacy in interpretations of apparently weird quantum phenomena, dating back to his work in 1959 to explain the Aharonov-Bohm effect, sometimes referred to as the Ehrenberg-Siday-Aharonov-Bohm effect in acknowledgment of a theoretical prediction of the effect in 1949. Experimental researchers had observed a phase shift in charged particles near an electromagnetic field even though the field was zero throughout the region occupied by the particle's wave function.

事实上，阿哈罗诺夫对于解释表面上怪异的量子现象已经有了他自己的贡献，那是在1959年，他的研究是为了解释阿哈罗诺夫-波姆效应，有时候也被称作埃伦伯格-西迪-阿哈罗诺夫-博姆效应，以确认一项在1949年的理论预测。实验研究者观察到，在接近电磁场时候，带电粒子会产生相变，即使粒子的波函数所穿过的电磁场的势为零的时候也是如此。

"Usually, people think only about the wave function," says Aharonov, referring to common descriptions of superposition. "They think about it mathematically but they don't connect it with a conserved quantity which is the modular momentum." By analyzing quantum effects in terms of the exchange of a conserved variable—the modular momentum—Aharonov and David Bohm were able to explain the Aharonov-Bohm effect. Now, alongside Rohrlich, he set about applying the same kind of analysis to the counterfactual quantum communication protocol.

“通常，人们只会考虑波函数，”阿哈罗诺夫说，他指的是对叠加的通常描述。“他们在数学上考虑这个问题，但是他们并不将它与一个守恒的性质相联系，这个性质就是模动量。”通过，在交换的守恒变量——即模动量方面来分析量子效应，阿哈罗诺夫和大卫波姆可以解释阿哈罗诺夫-波姆效应。现在，与罗利希一起，他开始应用类似的分析来尝试解释反事实的量子通讯协议。

Rohrlich and Aharonov considered two parallel transmission channels—one with Bob's end closed with a mirror and one with it open. (This also equates to a single transmission channel where Bob's mirror is in a superposition of open and closed states.) They then consider an initial wave function in a superposition of the state in the open-ended channel plus the state in the closed channel.

罗利希和阿哈罗诺夫考虑了2个平行的传输通道——其中一个Bod的一端关闭，但是固定有一面镜子，另一个通道中Bod的一端是打开的。（这也等同于，一个单个的传送通道，其中Bod的镜子是处于开和关的叠加态的）。他们于是考虑，一个初始的波函数，这个波函数处于一个叠加态，即，在通道的Bod一端处于开启状态，加上Bod端关闭的通道的状态。

The problem arises because, as Salih and co-authors had shown, the wave function evolves differently depending on whether Bob's end is closed or not. As a result, after a certain period of time has elapsed, the superposition will be the state of one channel minus the state of the other channel, but that equates to a different phase from the initial wavefunction. Since the modular angular momentum depends on the phase this suggests the modular angular momentum of the particle has changed even though the particle's wave function could not occupy the part of the channel where Bob has his mirror open or closed.

问题产生了，就像Salih和合作者展示的那样，波函数的演化取决于Bod的一端是开启还是关闭的。其结果就是，过了一段时间之后，叠加态就会变成，一个通道的状态减去另一个通道的状态，但是这等于初始的波函数中一个不同的相态。因为模角动量取决于相态，这暗示，即使，这个粒子的波函数，不能占据通道中Bob使镜子开启或关闭的部分——这个粒子的模角动量产生了改变。

"The only way to explain how the angular momentum did change is that part of the angular momentum of the particle left it and went to the other side," says Aharonov. As he and Rohrlich explain it, part of the angular momentum leaves the particle, enters the region of the transmission channel that the particle's wavefunction cannot, and there, it is absorbed by the mirror so that the value of the modular angular momentum on the particle is altered. They also suggest that similar results could result through considering the spin angular momentum and other conserved properties.

“唯一能够解释角动量确实改变了的方法是，这个粒子的角动量的一部分离开了这个粒子，并且到了另一端，”阿哈罗诺夫说。就像他和罗希利解释的那样，部分角动量离开了粒子，进入了通道中该粒子的波函数所不能进入的区域，并且，在那里，它被镜子吸收了，所以，这个粒子上面的模角动量的值被改变了。他们也提出，类似的结果，也可以从考虑，自旋角动量和其他守恒属性中得出。

Temperamental properties

不稳定的属性

Aharonov and Rohrlich liken the behavior of the particle and its modular angular momentum to the grinning Cheshire cat in "Alice's Adventures in Wonderland," which appears to move on, leaving its grin behind. "Although it's very surprising that properties can leave their particles, it is not as surprising as to say that nothing happened and there was an effect," says Aharonov, comparing their explanation with the idea of the particle with its properties encountering nothing that can change the modular angular momentum, yet that property changing anyway.

阿哈罗诺夫和罗利希把粒子的行为和粒子的模角动量比作，《爱丽丝梦游仙境》中咧着嘴笑的柴郡猫，它貌似在移动，却把它的咧着嘴的笑落在身后。“虽然粒子的属性可以离开粒子本身非常令人吃惊，但这，总不会比，那种什么也没发生，但就是有这么一个效应的解释，更让人吃惊吧，”阿哈罗诺夫说，他把他们的解释与，那种粒子和其属性什么也没有碰到就可以改变其模角动量，进而，不管怎么地就是改变了属性的想法做了对比。

Like all new concepts, Aharonov and Rohrlich's explanation is not without its criticisms, either. Rohrlich highlights the point raised by one of the (anonymous) peer reviewers of the paper, who nonetheless gave an overall positive appraisal of the paper. "They were saying, humorously, yes we avoided one problem, but we got ourselves into another problem," says Rohrlich. Yet he adds, "If you're talking about a cat and its grin, that's very strange, but of course, all of this has to translate back to elementary particles, and if an elementary particle loses its spin because its spin goes somewhere else—maybe that's something we can get used to."

像所有的新概念一样，阿哈罗诺夫和罗希利的解释也不是没有遭到批评。罗希利强调了他们论文的一位匿名评审人提出的一个问题，但无论如何这位审稿人总体上给出了积极的评价。“他们幽默地说，是的，我们避免了一个问题，但我们又让自己陷入了另一个问题中，”罗希利说。但是，他补充道，“如果你讨论的是一只猫和它的咧嘴笑，那就非常奇怪，但当然，所有这些都得翻译回基本粒子上来，如果一个基本粒子丢失了它的自旋，因为它的自旋到了其他别的地方——或许这是我们可以习惯的某种事情。”

PS:翻译仅用作学习，版权属于原作者和机构。

Explore further

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论文出处：More information: Yakir Aharonov and Daniel Rohrlich What is nonlocal in counterfactual quantum communication?, Physical Review Letters, Accepted Manuscript. https://journals.aps.org/prl/accepted/c3076Y6bI091ec55f9465bc9200223328b0ab042b

Arxiv: https://arxiv.org/abs/2011.11667

Journal information: Physical Review Letters  , arXiv

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