薛定谔的猫

本词条由Solitude初步翻译。

模板:Other uses
模板：其他用途

模板：简短说明 由物理学家埃尔温·薛定谔设计的思维实验

模板:More citations needed
模板：需要更多的引用

文件:Schrodingers cat.svg

Schrödinger's cat: a cat, a flask of poison, and a radioactive source are placed in a sealed box. If an internal monitor (e.g. Geiger counter) detects radioactivity (i.e. a single atom decaying), the flask is shattered, releasing the poison, which kills the cat. The Copenhagen interpretation of quantum mechanics implies that after a while, the cat is simultaneously alive and dead. Yet, when one looks in the box, one sees the cat either alive or dead, not both alive and dead. This poses the question of when exactly quantum superposition ends and reality collapses into one possibility or the other.

文件：薛定谔的猫：将一只猫，一瓶毒药和放射源入密闭容器。如果盒内监测器（例如盖革计数器）检测到放射性，即单个原子衰变，烧瓶会破碎，毒药释放，杀死猫。量子力学的哥本哈根诠释Copenhagen interpretation认为，一段时间之后，猫既活着又死了。但是，人们看向盒内时，猫不是活着就是死了，不是既活着又死了。这就提出了一个问题，量子叠加具体何时结束，现实何时塌陷成一种或另一种可能性。

Schrödinger's cat: a cat, a flask of poison, and a [[radioactive source are placed in a sealed box. If an internal monitor (e.g. Geiger counter) detects radioactivity (i.e. a single atom decaying), the flask is shattered, releasing the poison, which kills the cat. The Copenhagen interpretation of quantum mechanics implies that after a while, the cat is simultaneously alive and dead. Yet, when one looks in the box, one sees the cat either alive or dead, not both alive and dead. This poses the question of when exactly quantum superposition ends and reality collapses into one possibility or the other.]]

薛定谔的猫：将一只猫，一瓶毒药和放射源入密闭容器。如果盒内监测器（如盖革计数器）检测到放射性，即单个原子衰变，烧瓶会破碎，毒药释放，杀死猫。量子力学的哥本哈根诠释Copenhagen interpretation认为，一段时间之后，猫既活着又死了。但是，人们看向盒内时，猫不是活着就是死了，不是既活着又死了。这就提出了一个问题，量子叠加具体何时结束，现实何时塌陷成一种或另一种可能性。

Schrödinger's cat is a thought experiment, sometimes described as a paradox, devised by Austrian physicist Erwin Schrödinger in 1935, though the idea originated from Albert Einstein.薛定谔的猫是一个思想实验thought experiment，有时被称为悖论paradox，由奥地利物理学家埃尔温·薛定谔于1935年提出，但该想法起源于阿尔伯特·爱因斯坦。

Schrödinger's cat is a thought experiment, sometimes described as a paradox, devised by Austrian physicist Erwin Schrödinger in 1935, though the idea originated from Albert Einstein. It illustrates what he saw as the problem of the Copenhagen interpretation of quantum mechanics applied to everyday objects. The scenario presents a hypothetical cat that may be simultaneously both alive and dead,该实验表明了薛定谔认为的将量子力学quantum mechanics的哥本哈根诠释应用于日常物品所产生的问题，提出了一只可能同时活着且死去的猫。ref name"moring"{ cite book

 ——Solitude（讨论）该句意译

</ref> It illustrates what he saw as the problem of the Copenhagen interpretation of quantum mechanics applied to everyday objects. The scenario presents a hypothetical cat that may be simultaneously both alive and dead, a state known as a quantum superposition, as a result of being linked to a random subatomic event that may or may not occur.

}}</ref> a state known as a quantum superposition, as a result of being linked to a random subatomic event that may or may not occur.
这种状态被称为量子叠加quantum superposition，是与可能发生也可能不发生的随机亚原子事件相联系导致的结果。

The thought experiment is also often featured in theoretical discussions of the interpretations of quantum mechanics, particularly in situations involving the measurement problem. Schrödinger coined the term Verschränkung (entanglement) in the course of developing the thought experiment.模板:Quantum mechanics

The thought experiment is also often featured in theoretical discussions of the interpretations of quantum mechanics, particularly in situations involving the measurement problem. Schrödinger coined the term Verschränkung (entanglement) in the course of developing the thought experiment.

该思想实验也经常出现在对量子力学诠释理论的探讨中，特别是在涉及测量问题的情况下。薛定谔在提出思想实验的过程中创造了“量子纠缠”这个术语。

==Origin and motivation==
起源和动机

A life-size—and moveable—cat figure in the garden of Huttenstrasse 9, Zurich, where Erwin Schrödinger lived 1921–1926. A visitor to the house cannot know in advance where the cat will be.

埃尔温·薛定谔于1921年-1926年居住在苏黎世的胡特大街 (Huttenstrasse) 9号，屋子花园里有一座真实大小、可移动的猫形雕像，参观房子的人不会提前知道雕像的位置。 A life-size—and moveable—cat figure in the garden of Huttenstrasse 9, Zurich, where Erwin Schrödinger lived 1921–1926. A visitor to the house cannot know in advance where the cat will be.

埃尔温·薛定谔于1921年-1926年居住在苏黎世的胡特大街 (Huttenstrasse) 9号，屋子花园里有一座真实大小、可移动的猫形雕像，参观房子的人不会提前知道雕像的位置。

Schrödinger intended his thought experiment as a discussion of the EPR article—named after its authors Einstein, Podolsky, and Rosen—in 1935. The EPR article highlighted the counterintuitive nature of quantum superpositions, in which a quantum system such as an atom or photon can exist as a combination of multiple states corresponding to different possible outcomes.

Schrödinger intended his thought experiment as a discussion of the EPR article—named after its authors Einstein, Podolsky, and Rosen—in 1935. The EPR article highlighted the counterintuitive nature of quantum superpositions, in which a quantum system such as an atom or photon can exist as a combination of multiple states corresponding to different possible outcomes.

1935年，薛定谔本来想将该思想实验作为对EPR佯谬论文（以其作者爱因斯坦、波多尔斯基和罗森英文首字母命名）的讨论。EPR论文强调了量子叠加的反直觉性，在量子叠加中，一个量子系统，比如原子或者光子，可以处于多个状态，对应不同的结果。

The prevailing theory, called the Copenhagen interpretation, says that a quantum system remains in superposition until it interacts with, or is observed by the external world. When this happens, the superposition collapses into one or another of the possible definite states. The EPR experiment shows that a system with multiple particles separated by large distances can be in such a superposition. Schrödinger and Einstein exchanged letters about Einstein's EPR article, in the course of which Einstein pointed out that the state of an unstable keg of gunpowder will, after a while, contain a superposition of both exploded and unexploded states.

The prevailing theory, called the Copenhagen interpretation, says that a quantum system remains in superposition until it interacts with, or is observed by the external world. When this happens, the superposition collapses into one or another of the possible definite states. The EPR experiment shows that a system with multiple particles separated by large distances can be in such a superposition. Schrödinger and Einstein exchanged letters about Einstein's EPR article, in the course of which Einstein pointed out that the state of an unstable keg of gunpowder will, after a while, contain a superposition of both exploded and unexploded states.

当时的主流理论是哥本哈根诠释，它认为一个量子系统在与外部世界相互作用或被外部世界观察到之前，一直处于叠加状态。这时，叠加态会坍缩成一种或另一种定态。EPR实验表明，包含多个相距较远的粒子的系统可以处于这种叠加状态。薛定谔和爱因斯坦就后者的EPR佯谬论文通信，在信中，爱因斯坦指出，一个不稳定的火药桶会在一段时间后包含爆炸状态和未爆炸状态的叠加。

To further illustrate, Schrödinger described how one could, in principle, create a superposition in a large-scale system by making it dependent on a quantum particle that was in a superposition. He proposed a scenario with a cat in a locked steel chamber, wherein the cat's life or death depended on the state of a radioactive atom, whether it had decayed and emitted radiation or not. According to Schrödinger, the Copenhagen interpretation implies that the cat remains both alive and dead until the state has been observed. Schrödinger did not wish to promote the idea of dead-and-alive cats as a serious possibility; on the contrary, he intended the example to illustrate the absurdity of the existing view of quantum mechanics.

To further illustrate, Schrödinger described how one could, in principle, create a superposition in a large-scale system by making it dependent on a quantum particle that was in a superposition. He proposed a scenario with a cat in a locked steel chamber, wherein the cat's life or death depended on the state of a radioactive atom, whether it had decayed and emitted radiation or not. According to Schrödinger, the Copenhagen interpretation implies that the cat remains both alive and dead until the state has been observed. Schrödinger did not wish to promote the idea of dead-and-alive cats as a serious possibility; on the contrary, he intended the example to illustrate the absurdity of the existing view of quantum mechanics.

为了进一步说明，薛定谔描述了一种原则上可以在大型系统中创建叠加态的办法，即让该系统依赖于处于叠加态的量子粒子。他提出在一个密闭的钢制房间中放一只猫，猫的生死取决于放射性原子的状态，即原子是否衰变释放出放射性。薛定谔认为，哥本哈根诠释意味着这只猫在被观察到之前，既活着也死了。薛定谔并不认可猫既死也或是一种严谨的可能性，相反，他希望用这个例子说明量子力学现有观点的荒谬之处。

——Solitude（讨论）该句意译 

However, since Schrödinger's time, other interpretations of the mathematics of quantum mechanics have been advanced by physicists, some of which regard the "alive and dead" cat superposition as quite real. Intended as a critique of the Copenhagen interpretation (the prevailing orthodoxy in 1935), the Schrödinger's cat thought experiment remains a defining touchstone for modern interpretations of quantum mechanics. Physicists often use the way each interpretation deals with Schrödinger's cat as a way of illustrating and comparing the particular features, strengths, and weaknesses of each interpretation.

However, since Schrödinger's time, other interpretations of the mathematics of quantum mechanics have been advanced by physicists, some of which regard the "alive and dead" cat superposition as quite real. Intended as a critique of the Copenhagen interpretation (the prevailing orthodoxy in 1935), the Schrödinger's cat thought experiment remains a defining touchstone for modern interpretations of quantum mechanics. Physicists often use the way each interpretation deals with Schrödinger's cat as a way of illustrating and comparing the particular features, strengths, and weaknesses of each interpretation.

但是，自从薛定谔时代以来，物理学家提出了诸多其他量子力学的数学解释，其中一些解释认为 “既生又死”的猫叠加态非常真实。薛定谔的猫思想实验意在批判哥本哈根诠释（1935年的主流正统学说），至今仍是各种现代量子力学诠释的试金石，具有决定性意义。物理学家经常用各种诠释解释薛定谔的猫的方式来说明和比较各种诠释的特点、优点和缺点。

==Thought experiment==
思想实验

Schrödinger wrote:

One can even set up quite ridiculous cases. A cat is penned up in a steel chamber, along with the following device (which must be secured against direct interference by the cat): in a Geiger counter, there is a tiny bit of radioactive substance, so small, that perhaps in the course of the hour one of the atoms decays, but also, with equal probability, perhaps none; if it happens, the counter tube discharges and through a relay releases a hammer that shatters a small flask of hydrocyanic acid. If one has left this entire system to itself for an hour, one would say that the cat still lives if meanwhile no atom has decayed. The first atomic decay would have poisoned it. The psi-function of the entire system would express this by having in it the living and dead cat (pardon the expression) mixed or smeared out in equal parts.

薛定谔写道：

人们甚至可以提出相当荒谬的实验。把一只猫和盖革计数器，少量放射物质（设备必须不会干涉猫）一起关在钢制房间内。放射物质含量极少，也许一个小时原子就会衰变，但也有可能不衰变；如果原子衰变，计数管就会放电，并通过继电器释放出一个锤子，击碎装有氢氰酸的瓶子。如果我们把这整个系统单独放一小时，如果在此期间没有原子衰变，猫就还活着。第一次原子衰变会将它毒死。整个系统的普西函数将通过将活猫和死猫（原谅这个表达）混合或均分在相同部分来表达这一点。

Schroedinger: "The Present Situation in Quantum Mechanics." 5. Are the Variables Really Blurred?</ref>

Https://archive.is/20121204184041/http://www.tuhh.de/rzt/rzt/it/qm/cat.html#sect5 · 施罗丁格: 《量子力学现状》5.变量真的模糊了吗？] / ref

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It is typical of these cases that an indeterminacy originally restricted to the atomic domain becomes transformed into macroscopic indeterminacy, which can then be resolved by direct observation. That prevents us from so naïvely accepting as valid a "blurred model" for representing reality. In itself, it would not embody anything unclear or contradictory. There is a difference between a shaky or out-of-focus photograph and a snapshot of clouds and fog banks.

显然，这些实验中最初局限于原子域的不确定性转变为了宏观不确定性，这种不确定性可以通过直接观察得到解决。这使我们无法轻易地认为代表现实的“模糊模型”有效。它本身不会包含任何不清楚或矛盾的东西。摇晃或失焦照片与云层和雾层的快照是有区别的。

Schrödinger's famous thought experiment poses the question, "when does a quantum system stop existing as a superposition of states and become one or the other?" (More technically, when does the actual quantum state stop being a non-trivial linear combination of states, each of which resembles different classical states, and instead begin to have a unique classical description?) If the cat survives, it remembers only being alive. But explanations of the EPR experiments that are consistent with standard microscopic quantum mechanics require that macroscopic objects, such as cats and notebooks, do not always have unique classical descriptions. The thought experiment illustrates this apparent paradox. Our intuition says that no observer can be in a mixture of states—yet the cat, it seems from the thought experiment, can be such a mixture. Is the cat required to be an observer, or does its existence in a single well-defined classical state require another external observer? Each alternative seemed absurd to Einstein, who was impressed by the ability of the thought experiment to highlight these issues. In a letter to Schrödinger dated 1950, he wrote:

Schrödinger's famous thought experiment poses the question, "when does a quantum system stop existing as a superposition of states and become one or the other?" (More technically, when does the actual quantum state stop being a non-trivial linear combination of states, each of which resembles different classical states, and instead begin to have a unique classical description?) If the cat survives, it remembers only being alive. But explanations of the EPR experiments that are consistent with standard microscopic quantum mechanics require that macroscopic objects, such as cats and notebooks, do not always have unique classical descriptions. The thought experiment illustrates this apparent paradox. Our intuition says that no observer can be in a mixture of states—yet the cat, it seems from the thought experiment, can be such a mixture. Is the cat required to be an observer, or does its existence in a single well-defined classical state require another external observer? Each alternative seemed absurd to Einstein, who was impressed by the ability of the thought experiment to highlight these issues. In a letter to Schrödinger dated 1950, he wrote:

薛定谔著名的思想实验提出了一个问题：“量子系统何时会脱离叠加态转而坍缩为叠加态的其中一种状态？”（更严格地说，从何时起，实际的量子态不再是多个经典态的非平凡线性组合，而是开始有一个唯一的经典描述？）如果猫还活着，它只记得活着的状态。但是EPR实验的解释与标准的微观量子力学都要求猫和笔记本之类的宏观物体并不总是有唯一的经典描述。薛定谔的思想实验说明了这一显而易见的悖论。直觉告诉我们，没有观察者可以处于多种状态的混合，然而上述思想实验却表明，猫可以处于既生又死的混合态。猫是否需要成为观察者，或者需要另外一个外部观察者使得猫能够存在一个定义明确的经典状态？爱因斯坦认为每一种选择都很荒谬，猫的思维实验极大地突出了这些问题，令他印象深刻。在1950年写给薛定谔的一封信中，他写道：

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You are the only contemporary physicist, besides Laue, who sees that one cannot get around the assumption of reality, if only one is honest. Most of them simply do not see what sort of risky game they are playing with reality—reality as something independent of what is experimentally established. Their interpretation is, however, refuted most elegantly by your system of radioactive atom + amplifier + charge of gun powder + cat in a box, in which the psi-function of the system contains both the cat alive and blown to bits. Nobody really doubts that the presence or absence of the cat is something independent of the act of observation.

除了劳厄之外，您是现在仅存的物理学家，劳尔认为只有诚实的人才能绕开对现实的假设。他们中的大多数人根本不知道他们在玩什么样的冒险游戏——现实是独立于实验的。但是，你的系统——放射性原子+放大器+火药+盒子里的猫优雅地驳斥了他们的诠释，在这个系统里，普西函数既包含活着的猫，也包含被炸成碎片的猫。没有人真的怀疑猫的存在与否与观察行为无关。

Note that the charge of gunpowder is not mentioned in Schrödinger's setup, which uses a Geiger counter as an amplifier and hydrocyanic poison instead of gunpowder. The gunpowder had been mentioned in Einstein's original suggestion to Schrödinger 15 years before, and Einstein carried it forward to the present discussion.

Note that the charge of gunpowder is not mentioned in Schrödinger's setup, which uses a Geiger counter as an amplifier and hydrocyanic poison instead of gunpowder. The gunpowder had been mentioned in Einstein's original suggestion to Schrödinger 15 years before, and Einstein carried it forward to the present discussion.

请注意，薛定谔的装置中并没有火药，他用盖革计数器作为放大器，用氢氰酸毒药代替火药。火药是15年前爱因斯坦给薛定谔的最初建议中提到的，爱因斯坦在信中也一并讨论了。

==Interpretations of the experiment==
实验解释

Since Schrödinger's time, other interpretations of quantum mechanics have been proposed that give different answers to the questions posed by Schrödinger's cat of how long superpositions last and when (or whether) they collapse.

Since Schrödinger's time, other interpretations of quantum mechanics have been proposed that give different answers to the questions posed by Schrödinger's cat of how long superpositions last and when (or whether) they collapse.

自薛定谔时代以来，人们提出了许多其他的量子力学诠释，针对薛定谔的猫提出的叠加态持续多久以及他们何时（或是否）坍缩，这些诠释给出了不同的答案。

===Copenhagen interpretation===
哥本哈根诠释

Main article: Copenhagen interpretation

A commonly held interpretation of quantum mechanics is the Copenhagen interpretation. In the Copenhagen interpretation, a system stops being a superposition of states and becomes either one or the other when an observation takes place. This thought experiment makes apparent the fact that the nature of measurement, or observation, is not well-defined in this interpretation. The experiment can be interpreted to mean that while the box is closed, the system simultaneously exists in a superposition of the states "decayed nucleus/dead cat" and "undecayed nucleus/living cat", and that only when the box is opened and an observation performed does the wave function collapse into one of the two states.

A commonly held interpretation of quantum mechanics is the Copenhagen interpretation. In the Copenhagen interpretation, a system stops being a superposition of states and becomes either one or the other when an observation takes place. This thought experiment makes apparent the fact that the nature of measurement, or observation, is not well-defined in this interpretation. The experiment can be interpreted to mean that while the box is closed, the system simultaneously exists in a superposition of the states "decayed nucleus/dead cat" and "undecayed nucleus/living cat", and that only when the box is opened and an observation performed does the wave function collapse into one of the two states.

量子力学的主流诠释之一是哥本哈根诠释。该诠释认为，一个系统在观察时将不再处于叠加态，而是坍缩为叠加态中的任意一种状态。薛定谔的思维实验清楚地表明，哥本哈根诠释没有明确定义测量和观察的本质。实验可以解释为，盒子关闭时，系统处于“衰变的原子核/死猫”和“未衰变的原子核/活猫”叠加态中，只有打开盒子进行观察时，波函数才会坍缩成这两种状态之一。

However, one of the main scientists associated with the Copenhagen interpretation, Niels Bohr, never had in mind the observer-induced collapse of the wave function, as he did not regard the wave function as physically real, but a statistical tool; thus, Schrödinger's cat did not pose any riddle to him. The cat would be either dead or alive long before the box is opened by a conscious observer. Analysis of an actual experiment found that measurement alone (for example by a Geiger counter) is sufficient to collapse a quantum wave function before there is any conscious observation of the measurement, although the validity of their design is disputed. (The view that the "observation" is taken when a particle from the nucleus hits the detector can be developed into objective collapse theories. The thought experiment requires an "unconscious observation" by the detector in order for waveform collapse to occur. In contrast, the many worlds approach denies that collapse ever occurs.)

However, one of the main scientists associated with the Copenhagen interpretation, Niels Bohr, never had in mind the observer-induced collapse of the wave function, as he did not regard the wave function as physically real, but a statistical tool; thus, Schrödinger's cat did not pose any riddle to him. The cat would be either dead or alive long before the box is opened by a conscious observer. Analysis of an actual experiment found that measurement alone (for example by a Geiger counter) is sufficient to collapse a quantum wave function before there is any conscious observation of the measurement, although the validity of their design is disputed. (The view that the "observation" is taken when a particle from the nucleus hits the detector can be developed into objective collapse theories. The thought experiment requires an "unconscious observation" by the detector in order for waveform collapse to occur. In contrast, "the many worlds approach" denies that collapse ever occurs.)

但是，哥本哈根诠释的主要科学家尼尔斯·玻尔从未认为是观察者引起了波函数的坍缩，因为他并不认为波函数真实存在，它只是一个统计工具。因此薛定谔的猫对他来说不是什么谜题。早在意识的观察者打开盒子前，猫就已经死去或者仍然活着。分析一个真实的实验会发现，尽管实验涉及的有效性尚有争议，在有意识的观察者对测量结果进行观察前，测量本身（比如盖革计数器）就足以使量子波函数发生坍缩。（这种当原子核中的粒子撞击监测器时“观察”已经发生的观点可以发展为客观坍缩理论。在薛定谔的思维实验中，波函数要发生坍缩，监测器需要进行“无意识观察”。相比之下，“多世界理论”否认曾发生过坍缩。

===Many-worlds interpretation and consistent histories===
多世界诠释和历史一致论

文件:Schroedingers cat film.svg

The quantum-mechanical "Schrödinger's cat" paradox according to the many-worlds interpretation. In this interpretation, every event is a branch point. The cat is both alive and dead—regardless of whether the box is opened—but the "alive" and "dead" cats are in different branches of the universe that are equally real but cannot interact with each other.

The quantum-mechanical "Schrödinger's cat" paradox according to the many-worlds interpretation. In this interpretation, every event is a branch point. The cat is both alive and dead—regardless of whether the box is opened—but the "alive" and "dead" cats are in different branches of the universe that are equally real but cannot interact with each other.

用多世界诠释many-worlds interpretation解释量子力学“薛定谔的猫”悖论。多世界诠释认为每一个事件都是一个分支点。不管盒子是否打开，猫都是既活着也死了，但“活着的”和“死了的”猫在宇宙的不同分支中，同样真实但不能相互作用。

Main article: Many-worlds interpretation

In 1957, Hugh Everett formulated the many-worlds interpretation of quantum mechanics, which does not single out observation as a special process. In the many-worlds interpretation, both alive and dead states of the cat persist after the box is opened, but are decoherent from each other. In other words, when the box is opened, the observer and the possibly-dead cat split into an observer looking at a box with a dead cat, and an observer looking at a box with a live cat. But since the dead and alive states are decoherent, there is no effective communication or interaction between them.

In 1957, Hugh Everett formulated the many-worlds interpretation of quantum mechanics, which does not single out observation as a special process. In the many-worlds interpretation, both alive and dead states of the cat persist after the box is opened, but are decoherent from each other. In other words, when the box is opened, the observer and the possibly-dead cat split into an observer looking at a box with a dead cat, and an observer looking at a box with a live cat. But since the dead and alive states are decoherent, there is no effective communication or interaction between them.

1957年，休·埃弗莱特提出了量子力学的多世界诠释，该诠释并不把观察视为一个特殊过程。在多世界诠释中，盒子打开后，活猫和死猫仍然存在，但彼此之间是退相干的。换句话说，盒子被打开时，观察者和可能死亡的猫分裂成两个分支：观察者看着盒中的死猫，观察者看着盒中的活猫。但由于死态和活态是退相干的，它们之间无法发生有效的交流或相互作用。

When opening the box, the observer becomes entangled with the cat, so "observer states" corresponding to the cat's being alive and dead are formed; each observer state is entangled or linked with the cat so that the "observation of the cat's state" and the "cat's state" correspond with each other. Quantum decoherence ensures that the different outcomes have no interaction with each other. The same mechanism of quantum decoherence is also important for the interpretation in terms of consistent histories. Only the "dead cat" or the "alive cat" can be a part of a consistent history in this interpretation. Decoherence is generally considered to prevent simultaneous observation of multiple states.

When opening the box, the observer becomes entangled with the cat, so "observer states" corresponding to the cat's being alive and dead are formed; each observer state is entangled or linked with the cat so that the "observation of the cat's state" and the "cat's state" correspond with each other. Quantum decoherence ensures that the different outcomes have no interaction with each other. The same mechanism of quantum decoherence is also important for the interpretation in terms of consistent histories. Only the "dead cat" or the "alive cat" can be a part of a consistent history in this interpretation. Decoherence is generally considered to prevent simultaneous observation of multiple states.

打开盒子时，观察者与猫纠缠在一起，因此形成了对应猫生与死的“观察者状态”；每个观察者状态都与猫纠缠或联系在一起，因此“猫状态的观察”与“猫的状态”相对应。量子退相干确保不同的结果不会相互影响，对多世界诠释的历史一致论也很重要。在多世界诠释中，只有“死猫”或“活猫”才能称为一致历史的一部分。通常认为退相干是为了避免同时对多个叠加态进行观察。

A variant of the Schrödinger's cat experiment, known as the quantum suicide machine, has been proposed by cosmologist Max Tegmark. It examines the Schrödinger's cat experiment from the point of view of the cat, and argues that by using this approach, one may be able to distinguish between the Copenhagen interpretation and many-worlds.

A variant of the Schrödinger's cat experiment, known as the quantum suicide machine, has been proposed by cosmologist Max Tegmark. It examines the Schrödinger's cat experiment from the point of view of the cat, and argues that by using this approach, one may be able to distinguish between the Copenhagen interpretation and many-worlds.

宇宙学家马克思·泰格马克提出了薛定谔猫实验的一个变体，称为量子自杀机。它从猫的角度检验薛定谔的猫实验，并认为通过这种方法，人们或许能够区分哥本哈根诠释和多世界诠释。

===Ensemble interpretation===
系综诠释

The ensemble interpretation states that superpositions are nothing but subensembles of a larger statistical ensemble. The state vector would not apply to individual cat experiments, but only to the statistics of many similarly prepared cat experiments. Proponents of this interpretation state that this makes the Schrödinger's cat paradox a trivial matter, or a non-issue.

The ensemble interpretation states that superpositions are nothing but subensembles of a larger statistical ensemble. The state vector would not apply to individual cat experiments, but only to the statistics of many similarly prepared cat experiments. Proponents of this interpretation state that this makes the Schrödinger's cat paradox a trivial matter, or a non-issue.

系综诠释ensemble interpretation指出，叠加态不过是一个更大系综的子系综。态矢量不适用于单个猫实验，而仅适用于大量相似准备的猫实验的统计数据。该诠释的支持者认为，这使得薛定谔的猫悖论变得无关紧要，或者说根本不是问题。

This interpretation serves to discard the idea that a single physical system in quantum mechanics has a mathematical description that corresponds to it in any way.

This interpretation serves to discard the idea that a single physical system in quantum mechanics has a mathematical description that corresponds to it in any way.

这一诠释抛弃了单一量子力学系统有一个始终对应的数学描述这一观点。

===Relational interpretation===
关系诠释

The relational interpretation makes no fundamental distinction between the human experimenter, the cat, or the apparatus, or between animate and inanimate systems; all are quantum systems governed by the same rules of wavefunction evolution, and all may be considered "observers". But the relational interpretation allows that different observers can give different accounts of the same series of events, depending on the information they have about the system. The cat can be considered an observer of the apparatus; meanwhile, the experimenter can be considered another observer of the system in the box (the cat plus the apparatus). Before the box is opened, the cat, by nature of its being alive or dead, has information about the state of the apparatus (the atom has either decayed or not decayed); but the experimenter does not have information about the state of the box contents. In this way, the two observers simultaneously have different accounts of the situation: To the cat, the wavefunction of the apparatus has appeared to "collapse"; to the experimenter, the contents of the box appear to be in superposition. Not until the box is opened, and both observers have the same information about what happened, do both system states appear to "collapse" into the same definite result, a cat that is either alive or dead.

The relational interpretation makes no fundamental distinction between the human experimenter, the cat, or the apparatus, or between animate and inanimate systems; all are quantum systems governed by the same rules of wavefunction evolution, and all may be considered "observers". But the relational interpretation allows that different observers can give different accounts of the same series of events, depending on the information they have about the system. The cat can be considered an observer of the apparatus; meanwhile, the experimenter can be considered another observer of the system in the box (the cat plus the apparatus). Before the box is opened, the cat, by nature of its being alive or dead, has information about the state of the apparatus (the atom has either decayed or not decayed); but the experimenter does not have information about the state of the box contents. In this way, the two observers simultaneously have different accounts of the situation: To the cat, the wavefunction of the apparatus has appeared to "collapse"; to the experimenter, the contents of the box appear to be in superposition. Not until the box is opened, and both observers have the same information about what happened, do both system states appear to "collapse" into the same definite result, a cat that is either alive or dead.

关系诠释relational interpretation认为人类实验者、猫或装置之间，或者生命体与非生命体之间没有本质区别；所有这些遵循相同波函数演化规则的量子系统都可以被认为是“观察者”。但是关系诠释允许不同的观察者根据掌握的不同盒内系统信息，对同一系列事件给出不同的解释。猫可以被认为是装置的观察者；同时，实验者可以被认为是盒内系统（猫和装置）的另一个观察者。在盒子被打开之前，根据自身的死活，猫拥有关于设备状态的信息（原子要么已经衰变要么没有衰变）；但是实验者并不掌握这些信息。这样，在同一时刻两个观察者对于盒子的状态有不同的描述：对猫来说，装置的波函数“坍缩”了，对实验者来说，盒内系统处于叠加态。直到盒子被打开，两个观察者对所发生的事情都掌握了同样的信息，两个系统才“坍缩”为同样一个确定结果，既猫不是活着就是死了。

===Transactional interpretation===
交易诠释

In the transactional interpretation the apparatus emits an advanced wave backward in time, which combined with the wave that the source emits forward in time, forms a standing wave. The waves are seen as physically real, and the apparatus is considered an "observer". In the transactional interpretation, the collapse of the wavefunction is "atemporal" and occurs along the whole transaction between the source and the apparatus. The cat is never in superposition. Rather the cat is only in one state at any particular time, regardless of when the human experimenter looks in the box. The transactional interpretation resolves this quantum paradox.

In the transactional interpretation the apparatus emits an advanced wave backward in time, which combined with the wave that the source emits forward in time, forms a standing wave. The waves are seen as physically real, and the apparatus is considered an "observer". In the transactional interpretation, the collapse of the wavefunction is "atemporal" and occurs along the whole transaction between the source and the apparatus. The cat is never in superposition. Rather the cat is only in one state at any particular time, regardless of when the human experimenter looks in the box. The transactional interpretation resolves this quantum paradox.

在交易诠释transactional interpretation中，实验装置发射一个逆着时间行进的超前波，超前波与粒子源发射的顺着时间行进的波相互作用，形成驻波。这些波被认为是真实存在的，装置被视为“观察者”。在交易诠释中，波函数的坍缩是“非时间性的”，并且发生在粒子源与实验装置相互作用的整个阶段。猫从未处于叠加态，相反，不管人类实验者什么时候看盒子，猫在任何特定时间都只处于一种状态。这样交易诠释就解决了这一量子悖论。

===Zeno effects===
量子芝诺效应

The Zeno effect is known to cause delays to any changes from the initial state.

The Zeno effect is known to cause delays to any changes from the initial state.

量子芝诺效应zeno effect指延缓量子从对初始状态到其他状态的演化。

On the other hand, the anti-Zeno effect accelerates the changes. For example, if you peek a look into the cat box frequently you may either cause delays to the fateful choice or, conversely, accelerate it. Both the Zeno effect and the anti-Zeno effect are real and known to happen to real atoms. The quantum system being measured must be strongly coupled to the surrounding environment (in this case to the apparatus, the experiment room ... etc.) in order to obtain more accurate information. But while there is no information passed to the outside world, it is considered to be a quasi-measurement, but as soon as the information about the cat's well-being is passed on to the outside world (by peeking into the box) quasi-measurement turns into measurement. Quasi-measurements, like measurements, cause the Zeno effects. Zeno effects teach us that even without peeking into the box, the death of the cat would have been delayed or accelerated anyway due to its environment.

On the other hand, the anti-Zeno effect accelerates the changes. For example, if you peek a look into the cat box frequently you may either cause delays to the fateful choice or, conversely, accelerate it. Both the Zeno effect and the anti-Zeno effect are real and known to happen to real atoms. The quantum system being measured must be strongly coupled to the surrounding environment (in this case to the apparatus, the experiment room ... etc.) in order to obtain more accurate information. But while there is no information passed to the outside world, it is considered to be a quasi-measurement, but as soon as the information about the cat's well-being is passed on to the outside world (by peeking into the box) quasi-measurement turns into measurement. Quasi-measurements, like measurements, cause the Zeno effects. Zeno effects teach us that even without peeking into the box, the death of the cat would have been delayed or accelerated anyway due to its environment.

另一方面，存在加速量子系统演化的反芝诺效应。例如，如果你频繁地窥视放置猫的盒子，你可能会延迟或加速决定性选择。芝诺效应和反芝诺效应都是真实存在的，并且已知会发生在真实的原子上。被测量的量子系统必须与周围环境（在这个例子中是实验装置、实验室等）强耦合，以获得更准确的信息。但是，在薛定的猫实验中，没有信息传递到盒子外部，这种与环境的耦合被认为是一种准测量，但是一旦猫的生死（通过窥视盒子）传递到了盒子外部，准测量就变成了测量。准测量和测量一样都会引起芝诺效应。芝诺效应告诉我们，即使不窥视盒子，猫的死亡也会因为环境而被延迟或加速。

===Objective collapse theories===
客观坍缩理论

According to objective collapse theories, superpositions are destroyed spontaneously (irrespective of external observation), when some objective physical threshold (of time, mass, temperature, irreversibility, etc.) is reached. Thus, the cat would be expected to have settled into a definite state long before the box is opened. This could loosely be phrased as "the cat observes itself", or "the environment observes the cat".

According to objective collapse theories, superpositions are destroyed spontaneously (irrespective of external observation), when some objective physical threshold (of time, mass, temperature, irreversibility, etc.) is reached. Thus, the cat would be expected to have settled into a definite state long before the box is opened. This could loosely be phrased as "the cat observes itself", or "the environment observes the cat".

根据客观塌缩理论objective collapse theories，当达到某些客观物理阈值（时间、质量、温度、不可逆性等），叠加态会自动地被破坏（与外部观察无关）。因此，猫应该早在盒子被打开之前很久就已经稳定在一个确定状态。这可以粗略地称为“猫观察自己”，或者“环境观察猫”。

Objective collapse theories require a modification of standard quantum mechanics to allow superpositions to be destroyed by the process of time evolution.

Objective collapse theories require a modification of standard quantum mechanics to allow superpositions to be destroyed by the process of time evolution.

客观坍缩理论需要对标准量子力学进行修改，以允许叠加态被时间演化破坏。

==Applications and tests==
应用和测试

文件:Quantum superposition of states and decoherence.ogv

Schrödinger's cat quantum superposition of states and effect of the environment through decoherence

Schrödinger's cat quantum superposition of states and effect of the environment through decoherence

薛定谔的猫量子叠加态和退相干环境效应

The experiment as described is a purely theoretical one, and the machine proposed is not known to have been constructed. However, successful experiments involving similar principles, e.g. superpositions of relatively large (by the standards of quantum physics) objects have been performed. These experiments do not show that a cat-sized object can be superposed, but the known upper limit on "cat states" has been pushed upwards by them. In many cases the state is short-lived, even when cooled to near absolute zero.

The experiment as described is a purely theoretical one, and the machine proposed is not known to have been constructed. However, successful experiments involving similar principles, e.g. superpositions of relatively large (by the standards of quantum physics) objects have been performed. These experiments do not show that a cat-sized object can be superposed, but the known upper limit on "cat states" has been pushed upwards by them. In many cases the state is short-lived, even when cooled to near absolute zero.

薛定谔的猫实验是纯理论性的，所涉及的实验装置并被制造出来。但是，很多涉及类似原理的实验已经取得成功，例如一些（在量子力学标准中）相对较大系统的叠加态已经实现。这些实验并没有表明与猫大小一样的物体可以处于叠加态，但是这些实验提升了存在“猫态”的系统的大小上线。在很多实验中，即使冷却到接近绝对零度，猫态也只能短暂存在。

• A "cat state" has been achieved with photons.
  多光子的“猫态”已经实现。

• A beryllium ion has been trapped in a superposed state.
  观测到处于叠加态的被捕获的铍离子。

• An experiment involving a superconducting quantum interference device ("SQUID") has been linked to the theme of the thought experiment: "The superposition state does not correspond to a billion electrons flowing one way and a billion others flowing the other way. Superconducting electrons move en masse. All the superconducting electrons in the SQUID flow both ways around the loop at once when they are in the Schrödinger's cat state."
  一项涉及超导量子干涉仪（ SQUID）的实验与薛定谔思想实验的主题联系在一起：“叠加态并不是说十亿个电子正向流动，十亿个电子反向流动。超导电子总是沿同一方向移动，当超导量子干涉仪中的所有超导电子都处于薛定谔的猫态时，它们会同时在回路中双向流动。“

• A piezoelectric "tuning fork" has been constructed, which can be placed into a superposition of vibrating and non vibrating states. The resonator comprises about 10 trillion atoms.
  一种压电“音叉”已经被制造出来，可被置于振动和非振动状态的叠加态。谐振器包含约10万亿个原子。

• An experiment involving a flu virus has been proposed.
  一项涉及流感病毒的实验已被提出。

• An experiment involving a bacterium and an electromechanical oscillator has been proposed.
  一项利用机电振荡器和细菌的实验已被提出。

In quantum computing the phrase "cat state" sometimes refers to the GHZ state, wherein several qubits are in an equal superposition of all being 0 and all being 1; e.g.,

In quantum computing the phrase "cat state" sometimes refers to the GHZ state, wherein several qubits are in an equal superposition of all being 0 and all being 1; e.g.,

在量子计算中，“猫态”有时指GHZ态（Greenberg-Horne-Zeilinger态），其中若干量子比特处于全为0和全为1两种态的相等叠加态。

[math]\displaystyle{ | \psi \rangle = \frac{1}{\sqrt{2}} \bigg( | 00\ldots0 \rangle + |11\ldots1 \rangle \bigg). }[/math]

[math]\displaystyle{ | \psi \rangle = \frac{1}{\sqrt{2}} \bigg( | 00\ldots0 \rangle + |11\ldots1 \rangle \bigg). }[/math]

(| 00 ldots0 rangle + | 11 ldots1 rangle bigg).数学

According to at least one proposal, it may be possible to determine the state of the cat before observing it.

According to at least one proposal, it may be possible to determine the state of the cat before observing it.

至少有一种观点认为，有可能在观察猫之前就确定它的状态。

==Extensions==
扩展

Wigner's friend is a variant on the experiment with two human observers: the first makes an observation on whether a flash of light is seen and then communicates his observation to a second observer. The issue here is, does the wave function "collapse" when the first observer looks at the experiment, or only when the second observer is informed of the first observer's observations?

Wigner's friend is a variant on the experiment with two human observers: the first makes an observation on whether a flash of light is seen and then communicates his observation to a second observer. The issue here is, does the wave function "collapse" when the first observer looks at the experiment, or only when the second observer is informed of the first observer's observations?

“维格纳的朋友”是薛定谔实验的一个变体。实验中有两个人类观察者：第一个观察者通过观察确定是否看到闪光，然后将观察结果传递给第二个观察者。问题是，波函数究竟何时“坍缩”？是在第一个观察者进行观察时，还是只有当第二个观察者知道了第一个观察者的观察结果时？

In another extension, prominent physicists have gone so far as to suggest that astronomers observing dark energy in the universe in 1998 may have "reduced its life expectancy" through a pseudo-Schrödinger's cat scenario, although this is a controversial viewpoint.

另一方面，一些著名的物理学家甚至认为，通过一种伪薛定谔猫效应，天文学家在1998年对宇宙暗能量的观测可能会“缩短宇宙的预期寿命”，但这种观点非常具有争议。

| id =|bibcode = 2008PhRvL.100q1301K }}</ref>

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==See also==
另请参阅

• 基本功能 Basis function

• 互补性（物理） Complementarity (physics)

• 共识现实 Consensus reality

• 双缝实验 Double-slit experiment

• Elitzur–Vaidman炸弹测试仪 Elitzur–Vaidman bomb tester

• 半衰期 Half-life

• 海森堡切 Heisenberg cut

• 麦克斯韦的恶魔 Maxwell's Demon

• 测量问题 Measurement problem

• 微黑洞 Micro black hole

• 情态现实主义 Modal realism

• 观察者效应（物理） Observer effect (physics)

• 薛定谔故障 Schroedinbug

• 流行文化中的薛定谔的猫 Schrödinger's cat in popular culture

Further reading

• The EPR paper: Einstein, Albert; Podolsky, Boris; Rosen, Nathan (15 May 1935). "Can Quantum-Mechanical Description of Physical Reality Be Considered Complete?". Physical Review. 47 (10): 777–780. Bibcode:1935PhRv...47..777E. doi:10.1103/PhysRev.47.777.

• Leggett, Tony (August 2000). "New Life for Schrödinger's Cat" (PDF). Physics World. pp. 23–24. Retrieved 28 February 2020. An article on experiments with "cat state" superpositions in superconducting rings, in which the electrons go around the ring in two directions simultaneously.

• Trimmer, John D. (1980). "The Present Situation in Quantum Mechanics: A Translation of Schrödinger's "Cat Paradox" Paper". Proceedings of the American Philosophical Society. 124 (5): 323–338. JSTOR 986572.模板:Registration required

• Yam, Phillip (October 9, 2012). "Bringing Schrödinger's Cat to Life". Scientific American. Retrieved 28 February 2020. A description of investigations of quantum "cat states" and wave function collapse by Serge Haroche and David J. Wineland, for which they won the 2012 Nobel Prize in Physics.

External links

• A spoken word version of this article (created from a revision of the article dated 2013-08-12).

• Schrödinger's Cat from the Information Philosopher.

• Schrödinger's Cat - Sixty Symbols - a video published by the University of Nottingham.

• Schrödinger's Cat - a podcast produced by Sift.

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This page was moved from wikipedia:en:Schrödinger's cat. Its edit history can be viewed at 薛定谔的猫/edithistory