我們找到了一種新的方式來解釋為什么我們對實在的本質達成共識。

一個受進化論啟發(fā)的框架解釋了量子模糊性如何產生我們的經典世界，它表明即使是不完美的觀察者最終也能就客觀現實達成一致。

作者：卡梅拉·帕達維奇-卡拉漢

2026年1月27日

我們通常能對物體的外觀達成共識，但為什么呢？
Martin Bond / Alamy

從量子層面來看，我們的世界似乎本質上是模糊的，但我們實際體驗到的卻并非如此。研究人員現在開發(fā)出一種方法，可以測量我們所體驗到的客觀現實從這種模糊狀態(tài)中涌現的速度，這進一步證實了受進化原理啟發(fā)的框架能夠解釋客觀實在的涌現機制。

在量子領域，每個物體——例如單個原子——都存在于一系列可能的狀態(tài)之中，只有在被測量或觀測之后才會呈現出明確定義的“經典”狀態(tài)。但我們觀測到的卻是完全經典的物體，它們不存在任何模糊不清的部分，而造成這種現象的機制長期以來一直困擾著物理學家。

2000年，新墨西哥州洛斯阿拉莫斯國家實驗室的沃伊切赫·祖雷克提出了“量子達爾文主義”。他認為，類似于自然選擇的過程能夠確保我們所觀察到的物體狀態(tài)，是所有可能狀態(tài)中最“適應”的狀態(tài)，因此也是在到達觀察者的過程中，通過與環(huán)境相互作用而最能自我復制的狀態(tài)。當兩個只能接觸到物理實在片段的觀察者對某些客觀事實達成一致時，是因為他們觀察到的都是這些相同的復制體之一。

都柏林大學學院的史蒂夫·坎貝爾和他的同事們現在已經證明，即使不同的觀察者收集有關物體的信息的方式（即觀察物體的方式）不是最復雜或最精確的，他們也可能對客觀實在達成一致。

“如果一個觀察者捕捉到某個片段，他/她可以選擇進行任何他/她想做的測量。我也可以捕捉到另一個片段，我也可以選擇進行任何我想做的測量。那么，經典客觀性是如何產生的呢？這就是……”“我們出發(fā)的地方，”他說。

研究人員將客觀性涌現的問題重新定義為量子傳感中的一個問題。例如，如果待測的客觀事實是物體發(fā)光的頻率，那么觀察者必須獲得關于該頻率的精確信息，類似于配備光傳感器的計算機的工作方式。在理想情況下，這種裝置可以進行超精確的測量，并迅速得出關于光頻率的明確結論——這種情況可以用一個名為“量子費舍爾信息”（QFI）的數學公式來量化。在這項新研究中，研究人員紐約州羅切斯特大學的團隊成員加布里埃爾·蘭迪表示，他們以 QFI 為基準，比較了不同的、不太精確的觀測方案如何得出相同、準確的結論。

引人注目的是，該團隊的計算表明，對于足夠大的物理實在碎片，即使是進行不完美測量的觀察者最終也可以收集到足夠的信息，從而得出與理想的 QFI 標準相同的關于客觀性的結論。

蘭迪說：“一種簡單的測量方法實際上可以和更復雜的測量方法一樣有效。這是理解古典性出現的一種方式：當碎片變得龐大時�！弊銐蚨嗟臅r候，觀察者們甚至在簡單的測量上也開始達成一致�！� 通過這種方式，這項研究為我們理解為什么當我們觀察宏觀世界時，我們會對其物理屬性（例如一杯咖啡的顏色）達成一致提供了又一步。

“這項研究表明，完美、理想的測量并非必要，”阿根廷布宜諾斯艾利斯大學的迭戈·維斯尼亞奇（Diego Wisniacki）說道。他表示，量子信息不穩(wěn)定性（QFI）是量子信息理論的基石，但此前從未被引入量子達爾文主義，因此它可以將這個仍處于理論階段的量子框架與成熟的實驗（例如量子器件中的實驗）聯系起來。利用光基或超導量子比特。

“這是我們理解量子達爾文主義的又一塊‘磚’，”意大利巴勒莫大學的G·馬西莫·帕爾馬說。“而且，這種研究方法更接近于實驗學家對實驗室實際觀察結果的描述�！�

他說，研究人員在研究中使用的模型非常簡單，因此，雖然他們的方法可能為新的實驗打開大門，但還需要對更復雜的系統(tǒng)進行計算，才能使量子達爾文主義建立在更堅實的基礎之上。“如果我們能夠超越現有模型，那將是一項真正的重大突破。”帕爾馬說：“簡單的玩具模型。”

蘭迪表示，研究人員已經對將他們的理論研究轉化為實驗很感興趣——例如，使用由囚禁離子制成的量子比特，他們可以觀察客觀性出現的時間尺度與已知這些量子比特保持其量子性的特定時間相比如何。

期刊參考文獻：
《物理評論A》DOI：10.1103/hn78-7xx3
主題：
量子物理學

計量學方法論視角下的古典客觀性

安東尼·基利、戴安娜·A·奇澤姆、阿克拉姆·圖伊爾、塞巴斯蒂安·德夫納、加布里埃爾·蘭迪和史蒂夫·坎貝爾

《物理評論A》—— 2026年1月14日接收

DOI：https://doi.org/10.1103/hn78-7xx3

導出引用

摘要

我們提出了一種精確刻畫經典性出現過程的方法，該方法結合了量子達爾文主義的形式體系和量子計量學的工具。我們證明，量子費舍爾信息為評估經典客觀性涌現的速率提供了一個有用的度量。此外，我們的形式體系允許我們探究測量方法的選擇如何影響觀察者確定系統(tǒng)狀態(tài)的精度。對于自旋星模型的典型例子，我們證明了最優(yōu)測量會導致經典性以指數級速率涌現。雖然其他測量必然會導致較慢的涌現速度，但我們的重要發(fā)現是，次優(yōu)測量仍然可以達到克拉默-拉奧界限。通過將涌現的經典性重新表述為信息獲取協議，我們的框架為量子達爾文主義提供了一個精確的操作描述。

• ACCEPTED PAPER

Anthony Kiely, Diana A. Chisholm, Akram Touil, Sebastian Deffner, Gabriel Landi, and Steve Campbell

Phys. Rev. A -Accepted14 January, 2026

DOI: https://doi.org/10.1103/hn78-7xx3

Export Citation

Abstract

We present a precise characterization of the onset of classicality that combines the formalism of quantum Darwinism with the tools from quantum metrology. We show that the quantum Fisher information provides a useful metric for assessing the rate at which classical objectivity emerges. Furthermore, our formalism allows us to explore how the choice of measurement impacts the precision with which an observer can determine the state of the system. For a paradigmatic example of the spin-star model, we demonstrate that optimal measurements lead to the emergence of classicality at an exponential rate. Although other measurements necessarily lead to slower emergence, we importantly show that suboptimal measurements can still saturate the Cramér-Rao bound. By recasting emergent classicality as an information acquisition protocol, our framework provides a precise operational description of quantum Darwinism.

We have a new way to explain why we agree on the nature of reality

An evolution-inspired framework for how quantum fuzziness gives rise to our classical world shows that even imperfect observers can eventually agree on an objective reality

By Karmela Padavic-Callaghan

27 January 2026

We can usually agree what objects look like, but why?

Martin Bond / Alamy

Our world seems to be fundamentally fuzzy at the quantum level, yet we do not experience it that way. Researchers have now developed a recipe for measuring how quickly the objective reality that we do experience emerges from this fuzziness, strengthening the case that a framework inspired by evolutionary principles can explain why it emerges at all.

In the quantum realm, each object – such as a single atom – exists in a cloud of possible states and assumes a well-defined, or “classical”, state only after being measured or observed. But we observe strictly classical objects free of existentially fuzzy parts, and the mechanism that makes this so has long puzzled physicists.

In 2000, Wojciech Zurek at Los Alamos National Laboratory in New Mexico proposed “quantum Darwinism”, where a process similar to natural selection would ensure that the states of objects that we see are those that are most “fit” among all of the many states that could exist, and therefore best at replicating themselves through their interactions with the environment on their way to an observer. When two observers that only have access to fragments of physical reality agree on something objective about it, it is because they are both observing one of these identical copies.

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Steve Campbell at University College Dublin and his colleagues have now proved that different observers are likely to agree on an objective reality even if the way they gather information about an object – the way they observe it – is not the most sophisticated or optimally precise.

“If one observer captures some fragment, they can choose to do whatever measurement they want. I can capture another fragment, and I can choose to do whatever measurement that I want. So how is it that classical objectivity arises? That’s where we started,” he says.

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The researchers recast the problem of objectivity’s emergence as a problem in quantum sensing. If the objective fact at hand is, for example, the frequency at which an object shines light, then the observers must obtain accurate information about that frequency, in a similar way to how a computer equipped with a light sensor would. In the best-case scenario, this set-up could capture super-precise measurements and quickly reach a definitive conclusion about light’s frequency – a scenario quantified by a mathematical formula called “quantum Fisher information”, or QFI. In the new work, the researchers used QFI as a benchmark against which they could compare how different, less precise observation schemes reach the same, accurate conclusions, says team member Gabriel Landi at the University of Rochester in New York state.

Strikingly, the team’s calculations showed that for big enough fragments of physical reality, even observers doing imperfect measurements could eventually gather enough information to reach the same conclusions about objectivity as the ideal QFI standard.

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“A silly measurement can actually do as well as a much more sophisticated measurement,” says Landi. “That’s one way of seeing the emergence of classicality: when the fragments become big enough, observers start agreeing even with simple measurements.” In this way, the work offers another step towards understanding why when we observe our macroscopic world, we agree on its physical properties, such as the colour of a cup of coffee.

“The work highlights that perfect, ideal measurements are not required,” says Diego Wisniacki at the University of Buenos Aires in Argentina. He says that QFI is a mainstay of quantum information theory but it hadn’t been introduced into quantum Darwinism before, so it could bridge this still rather theoretical quantum framework with well-established experiments – for example, in quantum devices with light-based or superconducting qubits.

“This is one more ‘brick’ in our understanding of quantum Darwinism,” says G. Massimo Palma at the University of Palermo in Italy. “And is a way [of studying it] which is closer to an experimentalist’s description of what you actually observe in a lab.”

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The model the researchers used in their study is very simple, so while their method may open doors to new experiments, calculations for more complex systems will be needed to put quantum Darwinism on even firmer foundations, he says. “It would be a really great breakthrough if we could go beyond simple toy models,” says Palma.

Landi says the researchers are already interested in turning their theoretical investigations into an experiment – for example, with qubits made from trapped ions, where they could see how the timescale for the emergence of objectivity compares to the specific times during which those qubits are known to keep their quantumness.

Journal reference:

Physical Review A DOI: 10.1103/hn78-7xx3

Topics:

• Quantum Physics