Always Calculate: Physicist Ivan Terekhov on Fundamental Studies and Scientific Anecdotes

How did you decide on your career? Have you known since childhood you were going to be a scientist?

I grew up in a rural area in Irkutsk Oblast, where my chores were feeding the pigs and chickens; I also did sports – but otherwise, I was free to do as I pleased. I remember being glued to the children’s encyclopedia in second grade: it had many beautiful pictures, but I was most drawn to the laser. I understood that it only took three ingredients to make one: a ruby crystal, a mirror, and a lamp. With the last two it was easy, but the ruby was more challenging. Then I remembered that my mom had a ruby ring. So I brought it all to my dad and said “Let’s make a laser!” He took a hard look at me and suggested that we don’t do it, because mom would be upset. In any case, the ruby in the ring wasn’t fit for a laser – it had a different structure.

Did anything else pique your interest?

Generally, I really enjoyed pop-sci books. For example, I remember that in primary school I learned about the imaginary unit in math from a book, but it was only briefly mentioned, without a sufficient explanation. I tried asking the teachers at school; some said I would find out when I'm a little older. But someone advised me to talk to a high school teacher. I was surprised to learn that the imaginary unit is just a square root of -1, but then in middle school, when we studied equations, I could fully appreciate algebraic abstractions.

So your teachers supported your passion?

I had a great math teacher, Valentina Prichko. Even though she never raised her voice, everyone behaved in her class. What’s most important, though, is that she would assign everyone the tasks that suited their abilities. When my classmate and I developed an interest in math, she offered us problems for university applicants. This motivated me to study even more.

Later, in seventh grade, I was set on getting into the math-focused class, but my grades in other subjects were not on par with the requirements. I was so angry that I solved everything we were assigned to solve in the lesson within the first ten minutes. The teacher, who hadn’t worked with me before, was surprised – I clearly was fit for the math class – and three weeks later I was finally transferred there.

By that time, my classmates had covered quite a lot of geometry and I had to catch up. I remember the feeling of pieces finally clicking together after I solved several of the assigned problems – it was such a great pleasure.

Moreover, I happened to choose my future university in seventh grade, too. My physics teacher recommended that I go to Novosibirsk, not Moscow. Nearly all lecturers at the Faculty of Physics of Novosibirsk State University were researchers engaged in major projects at various institutes of the Russian Academy of Sciences. It was wonderful to learn first-hand about the top frontier fields and visit various labs to choose my specialization.

As far as I know, at university you focused on particle physics. What drew you to this theoretical field? It seems like experimental research is often considered more interesting.

As a second-year student, I visited the Budker Institute of Nuclear Physics as part of a tour: at that time, we had to choose our specializations. I remember as we sat in a big hall and every scientist came up to share their research. Then came the turn of Prof. Iosif Khriplovich, who said: “Do you really think that theoretical physicists come to the institute to think about great problems? No. Being a theoretical physicist means coming to work, pen in hand, and performing calculations. If you are stuck, you switch to another problem. The main thing here is to have discipline.” I remembered how I loved solving mathematical problems in school and realized that was what I wanted. Now I spend my days just like the professor described – I calculate my days away.

As a Bachelor’s student, I switched my specialization several times. First, I belonged to the Department of Plasma Physics, but I realized that I didn’t want to attend the same lectures for a second time – and switched to physics of nonequilibrium processes. There, I studied turbulent theory for a short time, right until I was offered a boring problem to solve.

As a Master’s student, I returned to particle physics, working under the supervision of Alexander Milstein. He had an interesting approach that meant you should be doing calculations all the time, even when you don’t want to. Prof. Milstein always offered his students the same task that he was working on. If a problem couldn’t be solved head-on, we came up with tricks – this way I studied and worked at the same time.

My experience at the institute taught me that there is no division between experimental and theoretical physicists. We all study the same nature, we just use different methods – therefore, we should work together, instead of building walls. There’s even a saying about that: calculating water density with high precision is not a task of theoretical physics – it’s easier just to measure it.

After graduation, you’d been working hard at universities in the UK, Germany, and Australia. How did this experience shape you as a professional?

For almost two years, I worked at the University of New South Wales and I was surprised to learn that the English in academia varied greatly from the “street” English. One day I decided to order a pizza. I went to a cafe, approached the counter, and couldn’t grasp what the cashier said. I asked them to speak more slowly, but still couldn’t even decipher any prepositions in that phrase. It became clear that I wasn’t getting any pizza that night.

Jokes aside, I didn’t expect physics to be such an unpopular field at the University of New South Wales. Students there opted for anything, but physics, even though there were quite a few Soviet physicists who moved there in the late ‘90s. It was different in Germany, though. The Max Planck Institute for Nuclear Physics could boast a good number of professionals but, in my view, still inferior to our specialists at the Budker Institute of Nuclear Physics.

And how did St. Petersburg and ITMO come into your life? Why did you join the ITMO Fellowship program?

As David Shapiro, professor at Novosibirsk State University, once said to me, working on one task for five years is unproductive – it’s better to switch to another task and get back to the first one if you get new ideas. That’s exactly what I did – I joined ITMO in October 2023.

I was drawn by the transparent working conditions and predictable salary that the program offers. Usually, how much researchers make depends on the number of grants they receive, but to win a competition and have yearly financing, we need to get results shortly and publish a ton. That’s impossible if you’re in fundamental science. Peter Higgs, the Nobel Prize-winning physicist, doubted that the discovery of the Higgs boson could be achieved in today’s academic culture; he would simply not have enough time and support needed for that. Some tasks require a lot of time and effort, especially if you don’t know how to better approach them. Thanks to the ITMO Fellowship, I can do science and not worry about financing. 

Also, as a fellow, I can work directly with students. Why is it important? As noted by John Wheeler, an advisor of Nobel Prize winner Richard Feynman, “We all know that the real reason universities have students is to educate the professors. But, in order to be educated by the students, one has to put good questions to them. If there are questions that the students get interested in, then they start to tell you new things and keep you asking more new questions. Pretty soon, you have learned a great deal.” I, too, share this belief.

Along with Stanislav Baturin, a researcher at ITMO’s Faculty of Physics, you received a ten-million-ruble grant as part of the Priority 2030 program. Tell us more about your project and other fields you pursue at ITMO.

I’ll start from afar. Kilometers of fiber optic cables are running along the bottom of the world’s oceans, transmitting hundreds of terabytes of data per second. If we want to transmit more data, we need to increase the capacity of those cables. Back in 1947, American engineer Claude Shannon coined information theory that explains how to transfer data more efficiently in linear channels. But the problem is that underwater cables are considered nonlinear data channels. In them, a signal interacts with noises and gets distorted, causing worse transmission quality and a greater number of errors. In order to transfer more data, we need theories similar to Shannon's, but for nonlinear channels.

We’ve already discovered a representation of the conditional probability density function as a continual integral. The function shows the probability of getting a certain signal as an output with a specific signal as an input. So far, we’ve performed calculations for a non-dispersive communication channel – the most common one in which all signal frequencies propagate at the same speed and the signal is not stretched. And with Stanislav Baturin, we’re working on a more complex case for the channel.

My other project focuses on electrical and electronic interactions in 2D materials. There are certain semiconductor materials that enable Cooper pairs, i.e. pairs of electrons that are formed due to interaction with phonons of the material’s crystal lattice. The first synthesized 2D material with unique properties was graphene. Its electrons behave as if they have no mass and at the same time a non-zero charge. The behavior seems odd as, in theory, if a material has a charge, there must be an interaction and therefore a mass – but that doesn't apply here. This phenomenon is studied, but there’s still a question of how such electrons interact with one another. 

We investigated the problem as we were looking into the interaction of two Dirac particles with the same charge. Usually, they repel one another, but under certain conditions there might occur a bound state of the Cooper pair type; electrons bind to one another on their own, without the lattice. This is a rather non-trivial fact. As a result, we realized that it was all because of the Fermi surface that can drastically change the behavior of electrons interacting.  

As a whole, this is helpful in predicting the properties of 2D materials, their reactions to impurities or current; and we use this knowledge to study transition metal dichalcogenides. These are used as single-photon emitters for nanolasers, quantum cryptography, or computing.

What do you do in your free time?

I’m a fan of gliding. As usual, it all started after I got invited to try it out once; I did and decided to learn to fly a glider. I took my first flight in 2008 and since then I have glided in Australia, Germany, the UK, and, of course, in Russia.