Conversation Nobel Laureate John Clauser Quantum computers are being exaggerated ......
The latest data show that Nobel Prize winners in physics typically wait an average of 20 years for the prestigious honor.
-- For John Clauser, that wait is more than twice as long.
On October 4, 2022, the 80-year-old physicist was named a co-recipient of the Nobel Prize in Physics, along with Alain Aspect and Anton Zeilinger. They are widely credited with conducting the groundbreaking "entangled photon experiment that established the violation of Bell's inequality and pioneered the science of quantum information.
Krause's research dates back to 1972: he confirmed the correctness of quantum mechanics and laid the foundation for emerging applications in cryptography and computing.
Recently, Krause is visiting Korea and gave a special lecture at Quantum Korea 2023, an international conference on quantum information hosted by the Ministry of Science and ICT and Korea University. The conference is part of the next Smart Forum to celebrate the university's 120th anniversary in 2025.
John Krause speaks with a reporter from the Korean newspaper JoongAng Ilbo at a hotel in Dongdaemun-gu, east of Seoul.
A reporter from Korea's largest media outlet, JoongAng Ilbo, met with the Nobel laureate at a hotel in Dongdaemun-gu, eastern Seoul, on June 26 to discuss his prize-winning achievements.
Q: Tell us about your award-winning research?
Krause: Basically, there was a debate between Niels Bohr and Albert Einstein about the meaning of quantum mechanics and whether quantum mechanics is a complete theory. It turned out that it was never fully resolved. In an attempt to understand where randomness comes from and where superposition in quantum mechanics comes from, he (Einstein) argued that quantum mechanics was not a complete theory. He wanted to add extra variables not in the theory - "hidden variables" - to explain entanglement.
So, what is entanglement? Schrödinger came up with two equations. The first equation describes hydrogen, which has one electron; the second equation describes helium, which has two electrons. In the second equation, he found that these two electrons were somehow intertwined and entangled; as Schrödinger claimed, this is a very complex way that is not understood, but it is necessary in order to explain the spectrum of helium.
According to Schrödinger's second equation, when two electrons are widely separated, they are still entangled in a very strange, intimate way. So the question then was, is this really correct? If they're closely together inside a helium atom, of course they're interacting. But if you separate them very far apart, they still interact according to quantum mechanics. This was very disturbing to both Schrödinger and Einstein. So Schrödinger even suggested that maybe the equation was wrong; maybe the entanglement of the electrons disappeared, but that would change the predictions of the theory. So this became a debate between Bohr and Einstein.
Einstein wanted to add extra variables, and Bohr said no: they weren't needed. Any change we can think of to the theory will change the predictions; and no one wants to admit that the predictions could be wrong.
--something just went wrong. So basically, this situation continued until 1964 when John Bell studied the theory.
What he found was a very surprising result. The fact that adding these extra variables to quantum mechanics, contrary to what Einstein, Boris Podolsky, and Nathan Rosen had predicted, was completely incompatible with, and changed, the predictions of quantum mechanics, is pure irony.
Then in 1969, when I was a graduate student, Michael Horne, Abner Shimony, Richard Holt, and I said that maybe quantum mechanics wasn't always completely correct. So we changed Bell's result into a form that could actually be tested experimentally.
So I ended up doing an experiment with Stuart Friedman in 1972. At the time, I didn't know what I was going to get when I did this experiment; but I knew I was going to somehow settle the debate between Bohr and Einstein. Frankly, I bet on Einstein: he was one of my big heroes; but what I didn't know was that in doing the experiment, I would find out that Einstein was wrong and Bohr was right.
I took the plunge and actually went out and tried to test it. In fact, I did four different experiments in the early '70s. Then the work of my co-Nobel laureate, Alain Aspe from Paris, was done in the '80s; Anton Zeilinger started in the late '80s and continued through the '90s and 2000s.
Since then, things have evolved significantly.
On November 7, 1975, Krauser and Stuart Friedman were at the quantum mechanics experiment used to test Bell's theorem at the University of California, Berkeley, where Krauser was a postdoctoral fellow.
Q: You mentioned in a previous article that when deciding to test Bell's proposal, everyone told you it was impossible, even your mentor. What prompted you to conduct this experiment?
Krause: I realized what was at stake; what was at stake was the entire platform of physics. Starting with Galileo and Newton and continuing with Einstein, there was a desire for a physical description, a description of how things move as a function of time in the three-dimensional world we live in, covered by differential equations.
The theory that Mike Horne and I have proposed shows that this is not possible. This is the whole basic platform that underpins Einstein's plan of attack for physics; unfortunately, we've pulled all the legs out from under the table on this one.
-- This was very disappointing; I recognized from the beginning that this was going to be a problem. mike Horne and I finally worked out all the details of doing this. No one else seemed to realize how risky it was to do these experiments, and that's what kept me going. Despite what everyone else told me, I was completely crazy to do these experiments and that it would ruin my career. Well, that's true. I've never been a professor.
But I think all my experiments are important.
Q: There are various quantum technologies being developed now that take advantage of quantum entanglement, such as quantum computers and quantum encryption satellites. What technologies do you consider to be the highest priority in terms of national development?
Krause: I suspect that, frankly, quantum computers are a bit overstated. The number of problems that ordinary computers can solve is in the millions or billions; there are only a handful of problems that quantum computers can usefully solve. Quantum encryption is the main driver of the new technology. Of course, the financial industry is very interested in encryption because it is able to send fully encrypted financial transactions and similar communications, just as all government agencies do with their secrets. Therefore, encrypted communication (even if it's just on your phone) is very important today. Therefore, quantum encryption is quite valuable; I would say it is more valuable than quantum computing.
Q: What is the required scale or number of entangled particles for satellite quantum communication, and is it possible to maintain entanglement at that scale?
Krause: It is possible. The first such satellite was the Chinese "Mozi" satellite, which was launched a few years ago. As far as I know, according to an article in Optics & Photonics News, the U.S. does not have any satellites for quantum encryption. Many other countries have projects that do quantum encryption.
As far as I know, the only real quantum encryption satellite in flight right now is the Chinese Mozi satellite. I think I've asked my colleagues why there are no U.S. satellites. And the best guess is that there are too many (potential) leaks along the way, too many ways to actually get it hacked, and too many ways to get it off the station.
Q: What other areas in quantum do you think have the potential to win the next Nobel Prize?
Krause: Good luck to them! It took me 50 years, and I don't know why it took so long. I guess some Nobel prizes have politics involved, and I'm just glad I got one. In physics, the most pressing problem I see is to somehow unify general relativity with quantum mechanics - I think entanglement is the source of some kind of problem in bringing the two together.
Q: What research topics do you think are critical for academia to create breakthroughs in quantum?
Krause: It's anyone's guess. Certainly, all of us who are doing this work are not expecting applications. We're just working on pure physics. But it's critical to have a good, strong scientific research program. Without that, we will get nowhere. Now, there are areas of physics that are being studied that I think are silly, such as string theory. But who knows? I can't predict that.
Now that you mention it, hopes are really high for quantum technology after quantum entanglement has been proven. Some say the market size will be worth more than 1 trillion won, or $77 billion, by 2030. Did you expect the market to grow that big 50 years ago?
Absolutely not. It's totally beyond what I ever dreamed of. At the time I did the experiment, I had no idea what results I would get. I bet on Einstein, but I didn't know what the result would be. I knew I would get a result, and I knew I would solve the debate. Other than that, I didn't know anything.
Q: Quantum is actually one of Korea's 12 national strategic technologies (technologies that the Korean government seeks to develop strategically). Do you have any thoughts on quantum research in South Korea?
Krause: I don't know enough about it to answer.
Q: What is the status of quantum research in the United States?
Krause: Certainly for science, U.S. science has been severely underfunded since Ronald Reagan's presidency. The science budget as a percentage of GDP has been routinely declining since the Reagan administration. Under Republicans, it has been declining. Under Democrats, it has tended to flatten. But the end result is that over the years it has fallen to one of the lowest levels in the world.
I'm very disappointed in the state of scientific research in the United States. In addition, there is competition between the so-called STEM universities and the liberal arts. The liberal arts seem to be trumping STEM. the end result is that science literacy, and especially math literacy, has declined. I strongly suspect that the Korean population may be better educated than the US population in general. I don't have statistics on that, but I wouldn't be surprised.
Q: In the long run, what do you see as the problem with underfunded STEM research?
Krause: It takes money to do research.
The United States effectively became the world leader in World War II. There was a lot of money going into scientific research, aeronautics, radar electronics, physics and atomic bomb research. There was just a lot of money being poured in: at the end of the war, scientists were leaving with a lot of new technology that they could apply to experimental physics that simply didn't exist before the war. It was an overnight change in the state of technology. It all had to do with the massive amount of government funding for the WWII effort.
Reference links:
[1] https://koreajoongangdaily.joins.com/2023/07/02/national/socialAffairs/korea-nobel-quantum/20230702123303418.html
[2] https://www.nobelprize.org/prizes/physics/2022/press-release/
