Quantum physics and quantum technologies are a very advanced area of science and technology—they are difficult and interesting, covering secure communications, ultra-sensitive sensors, supercomputers and, in the future, even medicine. The head of the Laboratory of Quantum Engineering of Light, Doctor of Sciences (Physics and Mathematics), Professor at Lomonosov MSU Sergey Kulik spoke about the modern development of quantum technologies and what it is like to study things that are not in our world.
– What are the most important modern developments in quantum physics and quantum technologies?
– Perhaps, the most important event was last year’s Nobel Prize for research in the field of entangled states. This refers to specific quantum states—entangled states. These are resource states, that is, it is possible to do something practical based on them. In this field, such actions are commonly referred to as protocols. A protocol is a set of actions that leads to a certain result. For example, there is a protocol of quantum cryptography, a protocol of quantum teleportation, etc. So, the Nobel Prize was awarded for the development and research of these states over several decades. This is exactly what we do here at SUSU, and at Moscow University, too. And this is very important: it is inspiring and shows that the world community has appreciated the contribution of scientists in this field. To speak about these states in a short popular-science interview is quite difficult, because in the classical world, in which we live, there are no analogues. They are things that simply do not exist in our world. So you don't have to try to understand them, you just have to accept them and believe in them.
– What was and is quantum physics studying? If it is possible to explain it for a broader audience.
– You see, quantum physics has experienced several stages of evolution. It began with the discovery of Max Planck, who predicted and described the features of the theory of radiation. And the first stage or the first quantum revolution was the moment when scientists managed to explain and predict effects that are called collective or ensemble, involving a large number of quantum objects: atoms, molecules, ions, photons. A prime example is the atomic bomb. And today this is virtually any object that runs on 220 V that we use: a computer, a smartphone, some laser pointers—all this is quantum physics, quantum technology. And this is the first milestone—collective effects, when there are a lot of quantum objects.
And since about the end of the last century, we are living in the era of the so-called second quantum revolution: experimental scientists have accessed individual quantum objects. All the same photons, ions, molecules, conducting contacts—just individual ones. And it turned out that studying the properties of such individual objects shows huge promise for quantum computing, quantum communication, and quantum sensing.
– Do you think quantum physics is more complicated or more interesting, if such categories can be applied to this field at all?
– It's both complicated and interesting. You have an option: either try to understand how it works, and then one of the options for your future is the madhouse, because it's impossible to understand it. Or you can try to accept it, believe in the literal interpretation of what other scientists were doing: Bohr, Heisenberg, Schroedinger—believe in their developments, and use it in your work. So yes, it's both challenging and very interesting. It's interesting to try to use in practice something when no one can understand how it works. For example, a quantum object, let's say an electron, has no trajectory, that is, it is impossible to know its coordinate and momentum simultaneously. In classical mechanics, if you take a pebble and throw it, you can tell what its location is and what the velocity is at any time. But in quantum mechanics, if you, say, throw an electron and exactly measure its coordinates at a particular point, you can't say anything about the direction and momentum. This is simply forbidden by the relevant laws. On the other hand, it is often possible to find analogies for quantum states. And these analogies help us just to survive and not to go totally crazy.
– Why did you choose quantum physics as your scientific field?
– As it happens, I did not choose. My dad, who is also a physicist by profession, sent me to the Physics Department of Moscow State University. So, I did not particularly think of where to enrol. And in the second year, I by total accident found myself in the laboratory, in which you might say I still am to this day. In this laboratory, they were working on the problems of quantum mechanics. I liked it there so much, it was so unusual, and there were such good people there in the human and professional sense, that I stayed there, stuck with it, and I still work in this field.
– What can you say about the development of this field at SUSU? What projects are being worked on now?
– SUSU, thankfully, is continuing with the traditions of the school of Boris Zeldovich and his students, who make up this school. But that school was mostly—and this is important to remember—theoretical scientists. And in quantum physics, you also need experimental research. When I began to work at both SUSU and MSU, we tried to formulate some conceptual directions in which we could move in terms of experiments. Now we are conducting experiments related to one of the main effects of quantum optics—the effect of photon anticorrelation. The experiment has been going on for about 9 months, and for the last two weeks, as they say, things are really cooking! In my opinion, over this whole period, the experimenters from SUSU worked very well; they are already quite independent researchers. This is very important. And also—and I am constantly talking about this—we need young professionals. We need to attract students in every way possible and hold on to the best ones.
– On that note, a question about young professionals: are there many of them coming into the field now?
– Students and young scientists are slowly appearing. But the personnel and professional issue is still very pressing; it's still a problem. And not only in terms of whether young specialists join us or not. The level of training of these individuals, these personnel, is very important. In general, all quantum technology is a very complex topic, heavily saturated with both science and technology. It takes at least five years to train a qualified specialist in this field. Minimum. And, of course, these specialists must know general areas of physics, such as quantum mechanics, statistical physics, thermodynamics, and so on. All of this has to be in the education system. We are trying to do this right now: for example, SUSU is currently developing new Bachelor's and Master's degree programmes. This is a very important process that contributes to the qualitative development of this field at SUSU. It is true that the results will not come quickly. But this process is underway. That’s the most important thing.
– Every now and then we hear the phrase “quantum computer”. What is it? And how close is this phenomenon to becoming a reality?
– I already mentioned quantum computing as one of three sub-technologies of quantum technologies. Developments in this direction should lead to creation of quantum computing devices, quantum computers. In general terms, this is a device that operates based on the laws of quantum mechanics and which, as it turns out, can significantly increase the speed of computing devices. But this is mostly related to a certain class of mathematical problems—optimization or overshooting, when you need to process a large array of data according to particular characteristics and find the right solution. There are a lot of these problems in life. For example, the travelling salesman problem: when a salesman needs to travel through a number of cities in the most logistically profitable way. If there are more than 40 cities, no classical supercomputer can optimize the route. And if there are, for example, 100 cities, it's even worse. Although such large numbers do not yet occur in the tasks which are important to solve today. A quantum computer, if it is created, will solve this problem.
These are also certain tasks related to materials science, synthesis of new materials, personal medications (individual medicine), algorithms for making the right decision, etc.
The world is slowly moving towards creating low-power quantum computers. But we are not yet saying that the small quantum computers that already exist exceed classical analogues. And I don't like to make any predictions. I prefer the formulation that everything depends on how much nature wants to give away its secrets to us. This, of course, is smug and somewhat humanitarian. So far, we are struggling, and the results are still very modest. But we are moving forward. Onward, toward a brighter future.
On June 7th, a science-to-practice seminar on quantum technologies will be held at SUSU. The seminar is organized by Sergey Kulik.
The scientific portion of the seminar will discuss the development of quantum computing technology, the development and creation of an inter-university quantum network (IUQN), the training of personnel for the practical application of quantum technologies, and the implementation of pilot projects based on the IUQN infrastructure.
The practical part of the seminar will consider aspects of the application of quantum technologies in the field of information security.
The seminar is primarily focused on industrial and financial organisations of the region: industrial enterprises, banks, and government agencies.
You can find the seminar program here and the abstracts of participants' presentations here.
Link to the live stream of the seminar: https://youtube.com/live/vAutErb_bdk?feature=share