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Quantum Chance: Nonlocality, Teleportation and Other Quantum Marvels

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Quantum physics, which offers an explanation of the world on the smallest scale, has fundamental implications that pose a serious challenge to ordinary logic. Particularly counterintuitive is the notion of entanglement, which has been explored for the past 30 years and posits an ubiquitous randomness capable of manifesting itself simultaneously in more than one place.
This amazing 'non-locality' is more than just an abstract curiosity or it has entirely down-to-earth applications in cryptography, serving for example to protect financial information; it also has enabled the demonstration of 'quantum teleportation', whose infinite possibilities even science-fiction writers can scarcely imagine.
This delightful and concise exposition does not avoid the deep logical difficulties of quantum physics, but gives the reader the insights needed to appreciate them. From 'Bell's Theorem' to experiments in quantum entanglement, the reader will gain a solid understanding of one of the most fascinating areas of contemporary physics.

132 pages, Paperback

First published June 6, 2014

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Nicolas Gisin

6 books11 followers

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Profile Image for Charles Daney.
78 reviews28 followers
April 29, 2016
The author, Nicolas Gisin, is a world-class expert in the subject of the book's subtitle: quantum "nonlocality, teleportation, and other quantum marvels". He was a principal investigator of an experiment – performed in 1997 near Geneva, Swizerland – that gave nearly watertight evidence for one of the strangest properties of quantum theory: "nonlocality". This is the main topic of the book, which was published in 2014 and is just about the most recent one that covers the subject for the non-professional reader.

What is "nonlocality”? Answering that question, in terms an educated layperson can understand, is the purpose of the book. All I can do here is try to indicate the gist of the matter. In 1935 Albert Eistein, with two collaborators (Boris Podolsky and Nathan Rosen) published a paper describing a thought experiment that seemed to show an inconsistency between quantum mechanics and special relativity. This became known as the "EPR paradox”. The thought experiment was based on a pair of elementary particles, such as electrons, that had been prepared in what is called an "entangled” state. That means any measurement made on certain properties of one particle must be correlated with a related measurement of properties of an entangled particle (as long as they don't interact with any other particles). And this must be true no matter how far the particles are separated in space and time when the measurements are made.

The possibility of entanglement of quantum particles is predicted by quantum theory. However, because of Heisenberg's uncertainty principle it leads to an apparent paradox if the particles happen to be far enough apart at the time of measurement so that no signal can pass between them in the time between the two measurements. That's because Einstein's Special Theory of Relativity requires that no information can be transmitted from one point to another faster than the speed of light.

When certain measurements are made on one particle of an entangled pair, then a related measurement on the other particle must turn out in a specific way no matter how far apart the particles are. And the result of measuring the second particle would probably have been different if the first particle hadn't been measured. In other words, a measurement at one place seems able to affect instantaneously a measurement somewhere perhaps very distant, in apparent violation of the special theory of relativity.

This also seems to violate the kind of indeterminacy required by quantum mechanics, because typically measurement of quantum properties can yield a number of distinct results, each with a particular probability. More specifically, a quantum particle can be in a "superposition” of distinct "pure states". After the measurement, the particle will be in only one of the pure states, with perhaps a different probability for each result. However, for particles that are entangled, the result of the first measurement can uniquely determine the result of the second. It is as though information about the first measurement somehow influences the other one.

Yet if the particles are so far apart that no information can pass from one particle to the other at less than or equal to the speed of light, then there is no way the second particle can know what measurement was made on the first particle or what the results were. To Einstein and many others it appeared that the only way out was that there must be some sort of unknown property (a "hidden variable") that was shared by both particles.

In order to perform an experiment to test this hypothesis (so that quantum mechanics and special relativity would be compatible) it was necessary to be able to create appropriate pairs of entangled particles, separate them at a distance large enough that no information could propagate from one to the other in the time between measurements, and derive an estimate of how much statistical discrepancy was possible between the measurements.

At the time of the EPR paper in 1935, physicists had no idea how to meet all those conditions. There were two reasons. First, there was no adequate technology then for creating and measuring entangled particles (e. g. electrons or photons) in order to carry out the experiment. Second, there was no clear idea of what sort of correlation would show whether or not hidden variables existed. The problem is that some correlations (greater than zero) could be expected depending on the nature of the experiment. (If two people each toss a coin, the results will agree half the time, a 50% correlation, even though it's completely random.)

The second problem was solved in 1964 by physicist John Bell. He proved mathematically that there was a numerical upper bound to a certain quantity that reflects correlations of the measurements, assuming that hidden variables exist and the rules of both special relativity and quantum mechanics applied. This numerical relation is called "Bell's inequality”.

In the early 1980s, Alain Aspect (who much later wrote the foreword to Gisin's book) and others were able to perform an actual experiment – and it was found that in fact Bell's inequality was violated. When a series of many tests were performed in which one of two related measurements were performed randomly (50% probability) on separated but entangled particles, the relevant quantity was larger than allowed by Bell's inequality if hidden variables existed. This cast substantial doubt on the idea of hidden variables (but only if they were "local", meaning they couldn't communicate information about their values at faster than the speed of light).

It's an important feature of such experimenta that there are two possible measurements that can be made. A hidden variable shared by the entangled particles might determine what outcome should occur for each measurement. Also, a hidden variable, if it existed, might carry information about which measurement was made on the first particle or the result. But the hidden variables assumed in Bell's theorem are local. Hence if the measurements are made when the particles are so far apart that no information from one measurement can reach the other before it's measured, then there is no way the second particle to be measured can "know" what measurement was made on the first one. The second particle "sees" the first particle as it existed before any measurement was made. (The existence of "nonlocal" hidden variables, whose information could be accessible everywhere in the universe instantaneously, is conceivable, but that's considered a very far-fetched possibility.)

More recently, Gisin's team and others have performed more rigorous experiments that make the conclusion even more watertight. Until quite recently there had been certain "loopholes” in experiments, related to the details of the experiment, that could cast doubt on the validity of the findings. But in 2015 results were published of three separate experiments that seem to close all loopholes physicists consider plausible. The conclusion is quite clear: Bell's inequality is violated. So unless either quantum mechanics or special relativity is wrong, there cannot be any "local hidden variables".

Since the particles in the recent experiments are sufficiently far apart when they are measured, special relativity doesn't allow information to pass from one measurement to the other. But since the measured correlations are found despite the large distance, the resulting correlation is called "nonlocal". In principle, it seems as though the separation can be as great as the size of the visible universe. This is why nonlocality, though now confirmed, is such a mysterious finding.

The key element in these experiments is the entanglement between the particles being measured. The modern theory of quantum mechanics was formulated a few years before 1930, and physicists knew about entanglement very soon afterwards. But it wasn't considered especially important or consequential before the EPR paper was published. Very few physicists saw its importance at an early date. Erwin Schrödinger was among the few, writing:

Entanglement is not one, but rather the characteristic trait of quantum mechanics, the one that enforces its entire departure from classical lines of thought.


Today, the phenomenon of entanglement is of utmost importance, not only theoretically, but also for practical applications. Without entanglement quantum communication, quantum cryptography, quantum "teleportation", and quantum computing would all be impossible. Some of these things are already commercially available products, not just laboratory curiosities.

Gisin's book further explains things mentioned in this review, especially the nature of the experiments that showed violations of Bell's inequality. However, not all of these topics are covered as thoroughly as they should be for a proper understanding. Quantum computing, for example, is hardly covered at all. The book's brevity (about 110 pages, not counting front material) is a virtue, in that it allows a focus on the central topic. But it's also a drawback because of how much of the whole story is omitted.

Here then are some shortcomings that you should be aware of.

1. The book uses hardly any mathematics at all, except for some simple probability arguments. Relatively simple mathematics could have been used effectively to better explain entanglement, Bell's inequality, and how things like quantum teleportation and quantum computing work.

2. The most difficult chapter in the book describes a "game" having a structure that reflects what is done in actual experiments. It may be more understandable, since the mathematics is slightly more transparent, but the game differs a lot from the physical experiments. It doesn't involve quantum concepts at all.

3. There is a very short discussion of quantum cryptography, but it's much too short for even a rudimentary understanding of how it works. So a reader never learns how quantum encryption makes it possible to detect any eavesdropping on a conversation.

4. There is no index or bibliography in the book. Lack of an index makes it difficult for a reader to locate where a particular topic or concept has previously been explained. Although some important references are given in footnotes, there's little help for a reader who wants to go more deeply into various important topics. This is especially a problem, since the book itself doesn't try to cover many topics in any real detail.

Despite these shortcomings, what the book does offer is very well done.

I've written another review of Gisin's book that goes into more a little more detail on some of the relevant physics. It's here.
415 reviews5 followers
January 1, 2019
I read this book under the recommendation of a Physics professor. To me, the book is a mixture of excitement and disappointment.
The topic of “quantum chance,” namely, the uncertainty in quantum measurement results, is a fundamental issue in quantum mechanics. Besides its profound philosophical and methodological implications, this topic also plays a critical role in various quantum technologies. Amazingly, in the past century, quantum physicists managed to make huge strides in quantum theory and applications, without fully understand the topic. Therefore, a book devoted to the issue of quantum chance would be very attractive to both physicists and none-physicists.
“Quantum Chance” started with an excellent explanation of the “Bell Game,” which shows that the correlation in measurements cannot be explained by local mechanisms (such as the hidden variables). The Bell game (and associated Bell Inequality) is the key verification of the non-locality of quantum mechanics. (Non-locality simply means that components in a quantum system are correlated in their measurements. Such a correlation cannot be explained by any local interactions. However, Bell Game does not provide more insight into such “non-local” interactions.)
Furthermore, the author argues that because of the non-locality and Einstein’s principle that no communications (i.e., exchange of information) can be conducted above light speed, a single measurement of a quantum quantity must be truly random (i.e., cannot be predicted by any current or future theories). Such argument rules out the “hidden variable” hypothesis. I am not sure if this is the standard reasoning as I was not exposed to the academic literature on this topic.
The book goes on to discuss some experimental details for verifying the Bell Inequality and efforts to remove various alternative explanations that preserve locality. The book then moves on to the topic of quantum cryptography, quantum computing and teleporting (as a way to transmit information rather than moving an object). A discussion of open research topics closes the book.
Overall, “Quantum Chance” provides a good introduction to the subject. However, its discussions are too centered on the Bell Inequality experiment, which is only a part of the puzzle of quantum entanglement. Therefore, I feel that “Quantum Chance” is not an appropriate title for the book. I’d prefer something like “non-locality” or “super correlation” based on the content.
Also, the narrative of the book is too repetitive. The same concept and statements appear multiple times, impeding the rhythm. Often times I open to a page and cannot tell whether it was read before. Perhaps the best way to read it is scanning quickly, and delve to details only when questions arise. I hope someone can condense the book to a much shorter version.
Profile Image for Anthony O'Connor.
Author 5 books34 followers
November 6, 2020
Excellent

An excellent account of Bell’s inequality - fully detailed in the form of a game where it is shown there is no possible way to get a score above three out of four in any kind of fully local process. Then we are shown how entanglement and non-local correlations from quantum physics enable us to get a higher score. Thus violating Bell’s inequality. All the way up to 3.4 or so. But intriguingly no higher. There is still no conceivable way to get a perfect score of 4. So nature is non-local but only so far. Relating to degrees of entanglement, still very much a research issue. The author presents some ideas on this and stresses why we should be puzzled. There is a beautiful explanation why non-local correlations imply true randomness. The other distinguishing feature of quantum physics in his view. There is an account of some of his own research - including the first case of producing entanglement outside the lab. Over 10 km! There are some astute and acerbic comments on the social/political history of quantum physics and the negative impacts of authority and tradition and the innate conservatism of any kind of established group. And yet stunning progress was accomplished anyway. A great introductory book. To be devoured with great enthusiasm.
Profile Image for Uladzislau.
369 reviews8 followers
September 23, 2023
В предисловии к этой небольшой книжке нобелевский лауреат 2022 г. по физике Ален Аспе пообещал, что выдающийся физик-экспериментатор, как швейцарец Николя Жизан, съевший собаку на квантовой запутанности, изложит читателю эту самую запутанность с такой подкупающей простотой и ясностью, что читателю останется только хлопнуть себя по лбу - как же он не дошел до сути вещей сам.
И начал Николя Жизан очень даже неплохо - парадокс ЭПР, игра Белла, Алиса и Боб, нелокальность - ну все хорошо, все понятно, благо теория вероятностей входит в круг моих профессиональных интересов и самую трудную, по словам автора, часть книги, я проскочил кавалерийским наскоком за полчаса, прискакал к самой квантовой запутанности, приготовился и ее понимать... И тут автор скромно заявляет, что на интуитивном уровне он эту квантовую запутанность объяснить не сможет, просто примем, что она существует, нарушает принцип локальности, посрамляет Эйнштейна, и теперь он нам расскажет как с ее помощью Алиса и Боб могут выиграть в игру Белла, а также какие захватывающие перспективы открываются в квантовой криптографии и иных сферах, как только мы сумеем эту запутанность ну сколь-нибудь надежно воспроизводить. Оставшаяся треть книги посвящается экспериментам автора и этим самым захватывающим перспективам.
Сказать, что я был разочарован - это ничего не сказать. С другой стороны, без привлечения головоломного математического аппарата, на интуитивном уровне нарушение локальности в виде квантовой запутанности объяснить профанам все равно не сумеет никто. В любом случае книга написана - ни о чем. Хорошо еще, что у автора хватило благоразумия ни словом упомянуть о таком мыльном пузыре последних лет, как "квантовый компьютер". Хотя та же квантовая криптография недалеко от него ушла. Ушла примерно в том направлении, где уже столько лет томятся такие пузыри, как сверхпроводимость при комнатной температуре, управляемый термоядерный синтез и нанотехнологии. Но я об этом громко говорить не буду, ибо такие пузыри нужны ученым, занимающимся фундаментальными исследованиями, чтобы выбивать финансирование. И я их в этом смысле понимаю.
Но, скажем так, потраченного на нее времени книга не стоит. Квантовая запутанность вам яснее не станет абсолютно.
Да, вот еще про что надо сказать, перевод книги - безобразен. Мало того, что он тяжеловесен и неудобочитаем, он еще изобилует ошибками, вызванными непониманием текста оригинала. Этот халтурщик - некто К. Ефимова.

P.S. Самое лучшее объяснение квантовой запутанности, которое мне попадалось - если вы надели носок на левую ногу, второй носок автоматически становится правым, сколь бы велико не было расстояние между ногами.
Profile Image for Peter Ells.
Author 2 books3 followers
February 21, 2022
I'll add more to this book review as I continue to read it.
Foreword
Alain Aspect, who wrote the Foreword, is extremely eminent. It was his team of scientists who performed the experiment that fist gave definitive evidence of quantum entanglement. During this, he restricted himself to scientific comments, merely noting that the experimental results proved that these strange correlations existed. Here he gives his philosophical views on realism and on free will.
On realism he writes (echoing Einstein, Schrödinger, and Einstein):
"The idea that one should give up the notion of physical reality is not one I find convincing, because it seems to me that the role of a physicist is precisely to describe the reality of the world, and not just to be able to predict the results that show up on our measurement devices".

On free will he writes:
"We may forget the desperate solution that consists in rejecting the notion of free will, a step that would make human beings into mere puppets under the direction of goodness knows what kind of Laplacian determinism".
Profile Image for Petr.
437 reviews
May 8, 2023
Although quantum physics are mind tangling, Mr Gisin manages to present them in a very accessible manner while still maintaining the awe connected to this field of physics and our venture into this incredible realm. The ultimate power move of Mr Gisin is demonstrating that the presented theory has already practical applications and is being used.

I would strongly recommend to anyone interested in quantum physics to read this book.
Profile Image for Eusse.
48 reviews5 followers
October 31, 2024
Un libro corto para adentrarse en el fascinante mundo del entrelazamiento y la no localidad. El autor se esmera en explicar, en un lenguaje simple y sencillo, cómo las predicciones de la mecánica cuántica van en contra del principio de localidad, dando paso a un fenómeno novedoso: la no localidad. Gisin expone, desde su perspectiva, cómo la no localidad tiene interesantes consecuencias sobre cómo entendemos el mundo, y cómo podemos construir tecnologías novedosas utilizando esta no localidad.
Profile Image for Harshal.
40 reviews3 followers
August 15, 2020
There's an intellectual revolution ongoing - and it's called quantum physics. Complex theoretical concepts explained in a simple, understandable manner. This book opens the door for further learning on nonlocal correlations & true randomness for the general audience.
Profile Image for Yasir Noori.
41 reviews
April 29, 2021
A wonderful book on some of the most mysterious natural phenomena that we know about. Nicolas Gisin, an expert who made many contributions to this field, explains it in very simple terms for the layman to understand. I highly recommend it.
Profile Image for Brendan .
784 reviews37 followers
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July 17, 2021
" No one knows what the universe is non-local "
Profile Image for Wing.
374 reviews19 followers
January 17, 2015
This book is miraculous. It manages to explain what Bell's inequalities are fully and comprehensively without using a single equation. Its trick is spreading the explanation well over 30 pages of very clear prose. It is written for lay readers who have already read something about quantum physics but who want to more deeply understand what entanglement is all about. I am a physician by trade and my mathematics is at high school level only. Yet I can honestly say I enjoy this book thoroughly. The book has an authoritative feel as the author is an engineer who has performed experiments to confirm quantum entanglement and is involved in producing quantum random number generators and quantum cryptography. These, together with quantum teleportation, are discussed, albeit rather briefly. For instance, only four pages are devoted on cryptography. Another highlight of the book is the philosophical implication of non-locality and entanglement this truly is very fascinating. Five stars!
Profile Image for Philip Holman.
15 reviews1 follower
July 29, 2015
Good information but........

I had a specific learning goal about entangled photons which unfortunately this book did not cover. My fault. I wonder too about the analogy of using the boxes to illustrate the concept of entanglement and correlation and the overall dilemma of EPR and Bell's inequality, something I understand but was confused in trying to follow the rules and strategy of the Bell game. I found the information on applications very interesting.
Profile Image for Serg.
16 reviews2 followers
June 26, 2018
Очень крутая книга хорошо описывающая квантовую запутанность. Но стало понятно, что у науки больше вопросов чем ответов. Мне понравился подход автора, он искренне стремится докопаться до сути вещей. Еще захотелось перечитать доклад Исконная Физика АллатРа, ведь именно он является "путеводной звездой" в мире физики тонких энергий.
Profile Image for Ilya Mamontov.
3 reviews1 follower
November 6, 2021
Непростая книга, сложные концепции. Тем не менее, это отличная работа, позволяющая понять концепцию квантовой физики практически без матаппарата. Рекомендую всем, кто не действующий физик, но интересуется состоянием современной науки.
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