This Tuesday the names of the three winners who will share the 2022 Nobel Prize in Physics were announced, they are Alain Aspect, John F. Clauser and Anton Zeilinger “for their experiments with entangled photons, establishing the violation of Bell’s inequalities and being pioneers in quantum information science.”
This in simpler words means that their results have cleared the way for new technologies based on quantum information, according to the Royal Swedish Academy of Sciences, the institution in charge of making the announcement, they have demonstrated the potential to investigate and control particles that are in entangled states. “What happens to one particle in an entangled pair determines what happens to the other, even if they are actually too far apart to affect each other.”
Regarding this award, El Economista spoke with Dr. Daniel Sahagún Sánchez, a researcher at the Department of Quantum Physics and Photonics and head of the Cold Atoms and Quantum Optics Laboratory at the National Autonomous University of Mexico (UNAM).
Sahagún Sánchez assures that this award is very exciting because John F. Clauser is a theoretician and participated in the first publication of Bell’s inequalities applied to a measurable system, which is when it was proven that quantum entanglement existed, later Alain Aspect did a better experiment and became famous, “so much so that for years those of us who are in the area and know him personally wondered why they hadn’t given it to him. That answer was because they were going to give it to him later (laughs the researcher)”.
The also atomic physicist shares that he knows the work of the winners because from the laboratory that he coordinates, experiments are carried out that have to do with the work of the three, especially with those of Clauser and Aspect, because they use atoms, while Anton Zeilinger uses crystals, that is, they use different material to generate twin photons.
He shares as an anecdote that he did his doctorate in England and his supervisor, Edward Hinds, was a friend of Alain Aspect, that’s why he had contact with his group, because they were also doing similar experiments, “we helped each other a little, we had small congresses, that’s why I feel part of this community and every time someone who belongs to it wins a Nobel Prize, I feel happy”. He said that although it is an achievement of theirs, it is definitely exciting that the area has their recognition, now because quantum technology is exploiting today.
Today in the country, Sahagún Sánchez is the only one that works in this area with atoms, even in Latin America there is only one other group, in Brazil; In fact, the researcher was inspired by the laboratory of his colleagues in that country to set up the one here. Four other laboratories in Mexico also carry out work, but with crystals.
quantum information
For most people, the term quantum information is beyond us, so the researcher gives us some clues to understand what is being rewarded today.
Sahagún Sánchez works on quantum optics, which is the application of quantum mechanics to light. “Any study of light with quantum properties, essentially the additional ingredient is quantum entanglement.”
He explains that this is a real problem and, in fact, what keeps them very busy “we are just working on the control of quantum states, it is something difficult and it is also difficult for us to understand it, especially since we can only create it in very particular situations And they have to be very controlled.”
The two methods of generating entangled photons are with lasers (by doing a special excitation on a crystal or atomic gas, which are nonlinear materials). When the excitations decay, occupying the same volume, the entangled photons are born; they are called that because they occupy the same quantum state and mathematically it is not possible to separate them.
He explains that this caused the community a lot of concern, in fact Albert Einstein was angry with the implications of quantum mechanics, he said that something was wrong because reality could not be probabilistic, “today experiments prove that at least once, Einstein was wrong.”
“What quantum mechanics predicts is that, for a single question, there are multiple answers and there isn’t one right and one wrong. What happens is that if you do the same experiment many times, it will not give the same answer every time, but on average it will always be the same answer, this is quantum mechanics”.
A new kind of quantum technology
The specialist explains that this is the second time that quantum technology has revolutionized the market. The first time was with the GPS. GPS works thanks to the fact that the satellites and the nodes here on earth have atomic clocks, which measure time with great precision and manage to synchronize the transactions to know if they are real because there must be a certain maximum time difference between emission and reception.
The other more visible to people is the location, the GPS has to measure time and distance, triangulate with a relatively simple mathematical model to generate your coordinates.
The second revolution is based on intertwining, a subject that today is awarded the Nobel Prize and is happening.
The most tangible example on the market is quantum cryptography, today there are many companies and startups working on it, companies like Google or Amazon are clear about it. “Amazon has just stopped a building in front of Caltech dedicated to quantum technologies and has just made an agreement with Harvard.”
“Here the entanglement element is used to make it more secure because almost all the information can go in a photon, that is, in a particle of light and if someone wants to intercept it, it destroys it. This is practically impossible to violate, according to physics.”
Currently, Sahagún Sánchez is working on developing the quantum internet hardware, he explains that in certain ways it is sophisticated, but in others not so much, that is, it can use the same fiber optic infrastructure that exists now, because light is light , but instead of sending laser light, entangled light is sent. “Today the repeaters are a problem and it is where I am doing experiments, my intention is to contribute in this area”.
What does quantum communication or information refer to?
It is possible to control particles in quantum entanglement, a state in which what happens to one particle determines what happens to another, despite being even miles away.
