Announcement of the 2022 Nobel Prize in Physics Transcript

Speaker 1: (07:05)
Welcome to this press conference at the Royal Swedish Academy of Sciences. [foreign language 00:09:41]. I think we will be on time, maybe one or two minutes late. Thank you.

Hans Ellegren: (17:30)
[foreign language 00:17:30]. Welcome to the Royal Swedish Academy of Sciences and this press conference, when we will announce this year’s Nobel Prize in physics. We will keep to our tradition and begin the presentation in Swedish and then continue in English. You are of course later on welcome to ask questions in either of these languages. [foreign language 00:17:54]. My name is Hans Ellegren. I’m the Secretary General of the Royal Swedish Academy of Sciences. And to my right is professor Eva Olsson, member of the Nobel Committee in Physics. And to my left, Professor Thors Hans Hansson, also member of the Nobel Committee in Physics, and expert in this field.

[foreign language 00:18:51]. This year’s prize is about the power of quantum mechanics. [foreign language 00:19:06]. The Royal Swedish Academy of Sciences has this morning decided to award the 2022 Nobel Prize in Physics in equal share to Alain Aspect, Université Paris-Saclay and École Polytechnique, Palaiseau, France. John F. Clauser, J.F. Clauser and Associates, Walnut Creek, California, USA. And to Anton Zeilinger, University of Vienna, Austria. They receive the price for experiments with entangled photons, establishing the violation of Bell inequalities and pioneering quantum information science. Professor Olsson will now give us a short summary, please.

Eva Olsson: (20:35)
Thank you. So quantum information science is vibrant and rapidly developing field. It has broad and potential implications in areas such as secure information transfer, quantum computing and sensing technology. Its origin can be traced to that of quantum mechanics, its predictions have opened doors to another world, and it has also shaken the very foundations of how we interpret measurements. What today is considered logical, measurable, and quantifiable was initially debated by Niels Bohr and Albert Einstein in philosophical terms. John Bell transformed the philosophical debate into science and provided testable predictions that launched experimental work. This year’s Nobel Prize in Physics honors the groundbreaking work and science of the central figures, Alain Aspect, John Clauser and Anton Zeilinger, who took up the challenges of Bell and tackled them in the laboratories. Professor Thors Hans Hansson will present the details of the work. Thank you.

Thank you, Professor Olson. And I’ll [inaudible 00:22:17] with Professor Thors Hans Hansson for a more detailed presentation.

Thors Hans Hansson: (22:21)
Thank you, Eva, for the introduction. Einstein, in a letter to a colleague, famously wrote, “I’m convinced that he…” And he meant God, “does not play dice.” And what did he mean with this? Quantum mechanics, the theory of atoms and life, had been immensely successful, but it was also very weird. For instance, take the simplest atom, hydrogen. Just one electron moving around the proton. Quantum mechanics couldn’t even tell you where the electron was, just the probability to find it somewhere. Einstein didn’t like that. He thought that good theory should give you precise predictions, just as Newton’s theory tells you exactly where the Moon is in its orbit around the Earth at every moment. Not everybody agreed.

Here are two of the founding fathers of quantum mechanics, Niels Bohr and Edwin Schrödinger. They thought that quantum mechanics was okay as it was, didn’t need anything more to just have to accept the peculiarities. And this position was put very clearly in this paper, written in 1935, by Edwin Schrödinger. It was an answer to a paper written earlier that year by Einstein Boris Podolsky and Nathan Rosen, and they had come up with the thought experiments, which they thought proved, demonstrated that quantum mechanics couldn’t be the full story. And now I will explain to you a modern version of that experiment. So here you see a source. These source emits pairs of particles, entangled pairs, Bell pairs. We’ll come back to that concept. And they reach Alice and Bob, who makes a measurement. They measure a property of these particles that is called spin.

And in quantum mechanics, this spin can only take two values, plus or minus. So what happens when you do it many times? Alice will see a sequence of pluses and minuses. Plus, minus, plus, plus, minus, minus, plus, et cetera. Looks completely random. And the same is true for Bob. But the strange thing is that when they compare the measurements, every time Alice sees a plus, Bob will see a minus and vice versa. And that’s very strange because they are far away from each other and these articles look exactly the same. Well perhaps, let’s look at it. Here we have the quantum cards. They look all the same, huh? We shuffle them or entangle them. And then here they go, and they can answer questions on signs. What sign do you have? Plus. What sign do you have? Minus. Okay. Let’s take another set of quantum cards. Here they go. What sign? Plus. What sign? Minus. Hmm. Strange. They look the same. How could they know what sign they had? Well, you see, here it is a trick. That is the following thing. Look, that was a minus and that was a plus. So each entangled pair had one plus and one minus. I [inaudible 00:26:19] whether the minus went there or there, but it was always one plus and one minus. So could it be that quantum mechanics was the same? Could it be that there were hidden information like on the cards? Could it be that nature was a trickster, just like I was before? Perhaps quantum mechanics is not complete. Perhaps there is something hidden. Einstein would have liked that, and it’s a very natural way to think that it would be like that. But years went on, decades went on. No one found such a theory that could explain the experiments with such hidden variables. So this became something more of a philosophical question.

Most physicists didn’t care very much, until in 1964, John Bell made an amazing theoretical discovery by looking at a variation of this experiment that I have told you about. He could show that in that case the predictions of quantum mechanics couldn’t be reproduced by any kind of theory based on hidden variables, however complicated. And when you think of it, that’s really strange because that means that when you measure on one of these particles, it’s not so that you asked to reveal a property that is already there and measure it. No. The quantum information about the state is in the full entangled state of both particles. Indeed, very strange.

And so thought the young John Clauser who said, “Ah, let’s do Bell’s experiment. Let’s perform it in the lab. Perhaps quantum mechanics isn’t right in that situation.” Now, that was easy to say, not so easy to do because with the existing lab equipment you couldn’t perform that experiment. But with collaborators, he came up with a variation of the experiment that could be performed. And he and the late Stewart Friedman went to the lab. They did it. And they found that quantum mechanics works also in this case.

Now, there were loopholes. And one particular loophole that John Bell had been very concerned about was that of locality. That means that Alice shouldn’t be able to send signals to Bob, so they could sort of agree on the result of the measurements. And that was hard to exclude experimentally. But in 1976, Alain Aspect wrote the paper where he proposed such an experiment, and a couple of years later went to the lab, performed the experiment, and yes, again, quantum mechanics rules. So why is this a big deal? They didn’t even know that quantum mechanics works. Well, to explain to you why it’s such a big deal, let’s go back again to 1935. Here is another paper by Schrödinger, in which he says, “I would not call entanglement one, but rather the great trait of quantum mechanics.” So now, much later in retrospect-

So now, much later in retrospect we understand that in addition to the profound philosophical and foundational implications of the studies of Bell states, the experiments performed by Clauser and Aspect opened the eyes of the physics community to the depth of Schrodinger’s statement. And provided tools for creating, and manipulating, and measuring states of particles that were entangled, although they were far away. And physicists now started to understand that entanglement and Bell pairs is a quantum resource that you can use to achieve amazing new things. And there’s no time here to even start to tell you that story. I will just give you one example which is picked, because it illustrates one of the many groundbreaking contributions by the third of this year’s laureates, Anton Zeilinger. So to understand this, you have to know that goal of quantum mechanics today is to build a quantum network.

What is that? A quantum network is a series of nodes and these nodes should be able to communicate via quantum entanglement. In these nodes you can have quantum devices like encryption devices. How do you build such a network? It’s difficult. Because entanglement is brittle. If you send it through an optical fiber, it very easily gets destroyed. So you need some new trick. And just an amplifier won’t work, because amplifiers destroy entanglement. So here is the trick, the method that Anton Zeilinger came up with. It’s called entanglement swapping. You have two of these Bell pairs like this. One of the particles, here one. And the other four goes far away from each other. The two other comes together. Here you make a measurement, so you entangle particle two and three. And then magically, one and four becomes entangled although they had never been close to each other. It’s wonderful.

So now you can think of doing it in a chain. You do one, you could do another, you do a third, et cetera, and you can build up a network. Another method to get long range entanglement is not to use optical fibers, but to send just light through the air. And I’ll just give you one spectacular example of this. And that was in 2018 where there was an intercontinental quantum link set up using the Chinese Micius quantum satellites between the group of Jian-Wei Pan, The Academy of Science in China, and with Anton Zeilinger’s group in Austria, over 7,600 kilometers. Pretty amazing.

And now we are at the forefronts of current research. And I will just end with a few comments. So today we honor three physicists whose pioneering experiments showed us that the strange world of entanglement and Bell pairs is not just the microworld of atoms, and certainly not the virtual world of science fiction or mysticism, but it’s the real world that we all live in. And researchers now all over the world, they use entanglement and Bell pairs, both in curiosity driven fundamental research and in utility driven applications, such as quantum cryptography or quantum computing. Thank you for listening.

Thank you. From Prof. Hansson. Now we shall see if we may have one of the laureates with us. Prof. Anton Zeilinger, are you there?

Anton Zeilinger: (34:36)
Yes, I’m here.

Good. Good morning Prof. Zeilinger.

Thank you.

Please accept our warmest congratulations to receiving the Nobel Prize in physics.

Thank you very much. It was very kind to receive your phone call just about an hour ago, and I’m still kind of shocked, but it’s a very positive shock. Thank you very much.

So were you surprised to get the call?

Yes, I was actually very surprised to get the call. Thank you.

Yeah, I’m sitting here in the session hall of the Royal Swedish Academy of Sciences, and we are at a press conference live here. There are many interested journalists from the international press, as well as from Sweden. Would you be ready to take some questions from them?

With pleasure, yes. But I don’t understand Swedish. But anyway…

I’m sure they will ask in English at least. Questions?

Right.

[inaudible 00:35:45]

Speaker 2: (35:50)
Hello, Prof. Zeilinger. Hello Prof. Zeilinger. [foreign language 00:35:52]. Congratulations. This is Swedish television. I’m curious, could you say something, you can read in the paper here that you demonstrated quantum teleportation, which does sound like something absolutely impossible. Could you say something, how it is possible?

Yes. Actually quantum teleportation uses the features of entanglement. It is not like in the Star Trek films or whatever, transporting something, certainly not a person, over some distance. But the point is using entanglement, you can transfer all the information which is carried by an object over to some other place where the object is, so to speak, reconstituted. And this is done, and that is actually the surprising feature. You can transfer the information without knowing the information. Because to know the information would violate I think perhaps, the uncertainty principle. So far this is only done this very small parties. And it is certainly, absolutely impossible to think of very large objects. But it’s fundamentally important for transferring information, maybe between quantum computers.

Okay. We have several hands raised. There was the one here, please.

Speaker 3: (37:34)
Yeah. Hi, Anton. This is Nordic Chinese Hands. First, congratulations on getting this year’s Nobel Prize in physics. Can you kindly share with us what inspired you of the idea of this topic? And to what extent will the work influence the future of the quantum physics, or even science in general?

Thank you very much for that question. I have to say that I was always interested in quantum mechanics, from the very first moments when I read about it. And I was actually struck by some of the theoretical predictions, because they did not fit the usual intuition which one might have. So I was lucky to work in Vienna with my supervisor, [inaudible 00:38:31], who is a pioneer in quantum physics. And he provided the freedom to do this, his experiments, which at that time were completely philosophical, without any possible user application. And this has changed now, as it has been mentioned. There are possible applications discussed, and also implemented in laboratories. The interesting point is that some of the fundamental questions, the very question, what does this really mean in a basic way, are still answered in my eyes. And that is an avenue for new research.

Speaker 3: (39:15)
Thanks so much for sharing.

Yeah. One question, there at the back.

David Keaton: (39:20)
David Keaton from the Associated Press. Congratulations, Professor. First of all, I’d like to ask, what in your opinion signifies this prize for the field in general of quantum mechanics? What does it mean for this field of research, do you believe? And second of all, in 2022 today, what excites you the most in this field? What areas do you think are going to be yielding the most new discoveries, both theoretical, but also maybe practical? Thank you.

Well, I guess this prize is an encouragement to young people. And I would mention here that the prize would not be possible without more than 100 young people who worked with me over the years and made all this possible. Because I alone could not have achieved this. That is quite clear. So I look at it as an encouragement, particularly for young people. My advice would be to do what you find interesting, and don’t care too much about possible applications. On the other hand, I understand this recognition is very important for the future development of possible applications. And this is going be quite interesting. I’m curious what we will see in the next 10 or 20 years. In my eyes, this is absolutely quite open. On the foundations, the fundamental thing, the issues about reality and the role of space- time in a very fundamental way is still not answered. And I expect some interesting experiments there in the coming years.

Okay. We have more question here, please.

Speaker 4: (41:16)
Congratulations, Prof. Zeilinger. So this is [inaudible 00:41:20] speaking from Geneva Observatory. So my question is, what happens if we send an entangled particle into a black hole? Do we still get information from it? Thanks.

Oh, this is a very basic question about the nature of black holes. And I should say I’m not a specialist on that. Well, you know that last year there was… Well, no there various different prizes for black holes. Also, there is the black hole in the center of the universe. And probably Prof. Genzel and Prof. Penrose can better…

I have a naive idea. My naive idea is that I think information cannot be lost forever. But that is just my personal opinion.

Yes, please.

Anneli Megner: (42:23)
Anneli Megner on Swedish TV4. Congratulations on the prize. I would like to fill in Thomas Von Heijne’s question from SVT. And when you were talking about teleportation, when I think of teleportation, I think teleportation of mass, like a person is jumping from here to there in different galaxies. But you said teleportation of information only. Is that correct? So there is no mass involved here?

Well, this is a very good question actually. I like that. The point is actually that it does not matter which mass something is composed of. So example, if I exchange all the carbon atoms in my body with the carbon atoms in somebody else’s body, I am still the person. That method, important is the information. Important is, how is the object constituted? How are all these constituents arranged together? And that is what defines individuality and so on, not the matter of which we…

Anneli Megner: (43:39)
So you mean that in the very, very future, maybe 10,000 years from now, you might be able, not to actually jump to another galaxy, but have yourself building up again from different material at another place? Like the same that we are sending TV now, for instance, that you get-

Well, at first I might say that I don’t think that I will experience anything in 10,000 years. So that’s a different question. The teleportation of people today, it’s the same kind of science fiction as it always was. So this is just science fiction and in my eyes, it is not a question of science.

Okay. Obviously very exciting topic with an exciting last question here. I think this was the last question from the press to you, Prof. Zeilinger. Thank you. And once again, our warmest congratulations for receiving the Nobel Prize in physics. We look forward to meet you here in Stockholm.

The Nobel Prize in physics. We look forward to meet you here in Stockholm in December at the Nobel Prize ceremony. See you then, Professor.

Speaker 7: (45:09)
Thank you very much again.

Bye-bye.

Okay, let’s move on to more questions about the Nobel Prize in physics, about the research, about the work of the committee, et cetera. Please, in either language, Swedish or English.

No questions. One here. Please, yes.

Speaker 5: (45:48)
Yes. Hello, my name is Linda Norasted. I’m from the technology newspaper, New Technique. I wonder if you could tell us a little bit about why you chose these three. Why is this knowledge worth the Prize?

Professor Hansson?

Well, in my presentation, I try to make clear what the three laureates did. And I should add, and I think I alluded to that in my explanation, that of course, Professor Zeilinger has also made a number of other groundbreaking contributions to the further developments. But when looking at the complete field that started, that was initiated by these groundbreaking experiments, the committee found that it would be wrong to just pick some of the very spectacular elements that has appeared lately, like teleportation. It’s something that really makes headlines, but we wanted to go back and also honor the people who laid the ground for what was to become. So that, in short, was the motivation.

By that, we will close the press conference. Thank you all for attending, and we hope to see you again here tomorrow at the same time. And we will present the Nobel Prize in chemistry for 2022. So thank you.

Speaker 6: (51:31)
Professor Thors Hans Hansson, member of the Nobel committee. Please explain what is this year’s prize about?

This year’s prize is about quantum mechanics, and I’m sure you’ve heard of quantum mechanics. And it usually is portrayed as something which is sort of very weird, very mystical. And it’s true, there are weird and almost mystical aspects of it. But this year’s prize is work that has made clear what quantum mechanics really means. And the really sort of funny thing with quantum mechanics is that normally you think if you have, say billard balls or something, you have one ball here, you have one ball there, you have one ball there. And you can look at this ball and you can say, Is it red or yellow or white? And you can look at it and it’s red, yellow, and white. Has nothing to do with the other balls. And then you can look at one of the others and see what color does that have.

In quantum mechanics, it works different. You can have quantum mechanical states, which are called entangled. And then when they are entangled, then you cannot just look at this one and say it’s yellow without somehow affecting what is happening to the other one. This is a very, very strange property of quantum mechanics. And what this year’s prize laureates have done is to make us understand a bit better about what is going on. They understand more about the nature, this peculiar feature of quantum mechanics.

Speaker 6: (53:27)
And how does it affect our daily lives or our lives?

Well, that’s a question you always get for the Nobel Prizes.

Speaker 6: (53:36)
Why not?

Yes, why not? So if we discover something about cosmos, what does it have to do with everyday life? Well, perhaps nothing, but it’s still wonderful that we can understand these things. And one aspect of this prize is exactly that. We something about nature that we didn’t understand or didn’t understand properly before. And that is something which is, in the committee’s opinion, is prize worthy in itself.

Then come to applications because there are certain prize. One year there was a price for blue dials, directly of importance for the bulbs you put in your socket. And there are aspects of this year’s prize that have some practical implications. For instance, you can have something that is called quantum cryptography. That is a way to use entanglement, this funny property I told you about, to send secret messages in a way that cannot be intersected, cannot be eavesdropped too. So that is one application that actually exists today, those devices you can buy. If they will become very important in the future, will it be only something for banks and militaries? I don’t know. But it is a practical application. Quantum computers might in the future. That’s in the doing. Still, we don’t have a quantum computer, but who knows?

Speaker 6: (55:17)
So why is this recognized now? Why now?

All of the experiments. The first experiments came very early. Still, the implications of the development that was set in motion hasn’t been clear before much later. I would say within the last 10, 15, 20 years. And then of course it’s always why this prize this year? That we never answer because there are of course many alternatives, and this year this alternative came on top.

Speaker 6: (56:01)
You were a little late and there are three laureates this year. Was there a problem finding them or?

Not so much actually.

Speaker 6: (56:14)
Could you tell us something personal about any of them? Is there something specifically interesting?

Oh, you mean finding-

Speaker 6: (56:21)
The laureates. No The laureates themselves as personalities.

Not really. I listened to talks to them, but I don’t know them personally.

Speaker 6: (56:32)
Yes, we heard Professor Zeilinger talk and he was really surprised and happy, of course. So finally, if you could tell me in 30 seconds why you specifically are so excited by this price, what would you say?

Well, quantum mechanics is an old love of mine. I wanted to become a mathematician. When I took it course from the mechanics, I decided to become a physicist. So quantum mechanics is the thing that made me start in physics. And I think I’m not the only physicist to have that experience.

Speaker 6: (57:06)
And the quantum world itself?

That is something that you never get finished with. You always ponder what is it? How do you understand it? And you try to go deeper and deeper into it.

Speaker 6: (57:22)
Thank you very much, Professor Thors Hans Hansson, member of the Nobel committee. Thank you.

Okay. [foreign language 00:57:32].

Speaker 6: (57:32)
[foreign language 00:57:32].

Announcement of the 2022 Nobel Prize in Physics Transcript

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