‘We Have Come Very Close to Exploring the Field of Superconducting Electronics’
Interdisciplinary research is a defining feature of modern science, and this trend is especially pronounced in the field of quantum technologies. Physics, chemistry, mathematics, and biology form the core fields of research at the Centre for Quantum Metamaterials of the HSE Tikhonov Moscow Institute of Electronics and Mathematics (MIEM). Prof. Alexei Vagov, director of the centre, discusses its key activities, which focus on exploring the prospects of creating materials with predefined properties through manipulating their structure at the quantum level.
What are Metamaterials? Quantum Metamaterials and Superconductivity
Nature offers a relatively limited range of materials; virtually all of them are already known, and their properties have been extensively studied. Today, however, science and technology have nearly reached the point where we can tailor materials to meet almost any requirement by altering their structure and, consequently, their properties through synergistic effects arising from the combination of different elements and the geometry of their microstructure. In other words, existing materials can be used as building blocks to create new materials whose properties are often entirely different from those of their constituent components. Such materials are known as metamaterials.
As more data is accumulated, our understanding of this field continues to expand. Metamaterials were once understood primarily as structures with specific optical and electromagnetic properties. Today, the focus extends beyond optics to include quantum, mechanical, and even biological properties, while the structures under study may be either highly ordered or entirely chaotic.
Our centre’s research is rooted in quantum physics and focuses on materials that exhibit quantum properties, foremost among them superconductors. In practice, superconductors are the most common way to realise the quantum properties of metamaterials at a macroscopic scale and at a level accessible to human observation—beyond the study of individual atoms or particles. Superconductors possess a number of unique properties determined by their quantum states. By controlling and manipulating these states, it becomes possible to create entirely new materials and devices.
Basic Research Comes First, Technology Follows
At the outset of a study, we can only hypothesise about the resulting properties, how closely they will match the desired parameters, and how stable they will be. Based on these projections, scientists outline a tentative roadmap for the work ahead. Along this path, filled with uncertainties, we encounter a wide range of unforeseen circumstances, making the journey inherently unpredictable. Yet the reward may be the discovery of a new material with the desired properties. This is the stage of basic research, which is where our work is primarily focused.
In my view, one particularly important area of research today is quantum superconducting electronics. Can a quantum diode be created? Scientists believe the answer is yes. Although research in this field is still at the stage of basic science, the diode effect—where different currents flow in opposite directions within a device—has already been demonstrated. This points to the possibility of a superconducting diode. For example, is it possible to create a superconducting device in which the current depends on an applied magnetic field—meaning the current can be controlled by the magnetic field? One magnetic field produces one current; a different magnetic field produces a different current. Or consider the dependence of current on controllable light: could a light-to-current converter be developed? We are actively exploring these areas, but there is still a shortage of fundamental knowledge needed to translate such ideas into practical technologies.
Whether all of this can be realised in practice remains a big question, but we have come very close to advancing the field of superconducting electronics. Notably, in this research, chemistry and physics effectively converge. It is impossible to 'assemble' a material with predefined properties without chemistry, while physicists provide the calculations that determine what should be done and how to do it. Moreover, biology also comes into play, as biomaterials have both chemical foundations and physical properties. Of course, these are fundamentally different disciplines, but in our field they work together. The phrase 'biological functions of a chemical element with physical properties' no longer sounds extraordinary.
Artificial intelligence? Absolutely!
In our research, we use well-established computational methods from quantum physics. However, the calculations have now become significantly more complex. Whereas in the past we dealt with relatively simple quantum-mechanical problems, today we need to perform highly precise calculations for complex systems. At this stage, a new level of theory comes into play—artificial intelligence. Our models have become extremely complex, so even a single calculation requires significant computational resources and time. Instead of performing an exact calculation each time, we construct a neural network model and train it to associate certain input parameters with specific outcomes, and other parameters with different outcomes. Once trained, we then use the neural network to predict the material parameters that correspond to the desired properties. In essence, this is an inverse problem, which is particularly important in our field of research. It can be addressed only with the help of AI, which identifies patterns based on previously performed calculations.
Incidentally, we test such problems using analogies that have nothing to do with the quantum world. For example, we tasked an AI with reconstructing musical scores for instruments from an existing piece of music. There are several subtleties that make this seemingly simple task far from easy, as musicians well know. We have even formed a small consortium around this work, bringing together physicists, programmers, and musicians.
What Technologies Are Already Available? The Role for MIEM
Basic research is followed by the development of useful technology. This occurs when we are able to define the purpose of a technology based on the already understood properties of a new material. In other words, we know precisely what we want to achieve. However, we are often still uncertain about how to achieve it. This is where technology developers come in. These areas are also an integral part of our centre's work.
The most obvious application of superconductors is lossless transmission of electricity. However, today the range of practical uses for superconductors has become much broader. I would highlight two key research areas in which progress has already reached a level that enables the development of working technologies.
The first area concerns the development of quantum electromagnetic field detectors. In particular, the creation of single-photon detectors for information transmission has emerged as a distinct research field, led at MIEM by Prof. Goltsman’s group. Another type of device already in use includes ultra-precise quantum magnetic field detectors, which are applied, for example, in mineral exploration.
The second research area focuses on the use of superconductivity in quantum computing, and it is in this and related fields that much of our centre’s research is concentrated. Within this domain, two main research tracks stand out in which technologies already exist.
The first track is fluxonium-based computing for precise magnetic field control and measurement, using the Josephson effect. In such systems, a superconductor is separated by a thin layer of normal material, and the resulting current is known as the Josephson current after the scientist who discovered it. The magnetic field penetrates in discrete portions, or quanta, which makes such devices suitable for quantum computing. The main drawback is that the computations involved are quite complex.
Another research track focuses on the creation and study of quantum states with topological properties. These states arise from the interaction of superconductors with other materials. In such systems, a special class of quantum states—known as Majorana states—can emerge. They are topologically protected, which allows their properties to be preserved and modified in a controlled way, enabling quantum computation.
Quantum computers based on fluxonium qubits already exist. There are no computers using Majorana states yet, but it is expected that, if such processors can be developed, they will be relatively easy to scale to millions of qubits on a single chip. Companies are already working on prototypes of this kind of processor. Compared with fluxonium qubits, the difference is—if I may use an analogy—similar to that between vacuum-tube and semiconductor electronics.
Our Partners
We have established close collaborations with scientists from MIPT and MEPhI, who provide the infrastructure for experimental research. We have also recently started working with JINR (Dubna), where unique opportunities exist to study the magnetic properties of materials using neutron scattering techniques. In addition, we are launching a partnership programme with MIET (Zelenograd), which hosts a major research initiative focused on the development of materials for electronics. Our centre also conducts a number of collaborative projects with scientists from other countries, including researchers from Brazil and China. In particular, we are involved in a large-scale project on the study of metamaterials together with colleagues from Brazil (the Federal Universities of Rio de Janeiro and Rio Grande do Sul) as well as Russia (HSE University, MIPT, and JINR).
As for partners from industry and business, we face a number of challenges. For manufacturers, the key priorities are stability, reliability, and profitability. We are currently exploring opportunities for collaboration with producers of batteries and solar panels.
Other Research Tracks: High-Entropy Materials
Another research track is the development of high-entropy materials (those composed of more than five components) for a new generation of batteries. These materials provide an interesting example of how improved energy storage can arise from structural disorder—essentially, from what might be called impurities. Incidentally, our research has shown that the presence of defects or disorder in a material’s structure can often enhance its superconducting properties. For such systems, the challenge is not to create an ultra-pure structure, but rather a 'dirty' one that enhances the material’s properties. Research suggests that we may be on the verge of replacing the cathodes in lithium-ion batteries with high-entropy materials in the near future.
To summarise, I would like to emphasise that the study of new types of functional materials, including superconducting metamaterials, is more relevant than ever. This is precisely the focus of our centre. Our research objective can be formulated as follows: how to create new superconducting metamaterials from superconductors that can be used in practical electronic applications.
See also:
Physicists Propose New Mechanism to Enhance Superconductivity with 'Quantum Glue'
A team of researchers, including scientists from HSE MIEM, has demonstrated that defects in a material can enhance, rather than hinder, superconductivity. This occurs through interaction between defective and cleaner regions, which creates a 'quantum glue'—a uniform component that binds distinct superconducting regions into a single network. Calculations confirm that this mechanism could aid in developing superconductors that operate at higher temperatures. The study has been published in Communications Physics.
Scientists Discover How Correlated Disorder Boosts Superconductivity
Superconductivity is a unique state of matter in which electric current flows without any energy loss. In materials with defects, it typically emerges at very low temperatures and develops in several stages. An international team of scientists, including physicists from HSE MIEM, has demonstrated that when defects within a material are arranged in a specific pattern rather than randomly, superconductivity can occur at a higher temperature and extend throughout the entire material. This discovery could help develop superconductors that operate without the need for extreme cooling. The study has been published in Physical Review B.
Researchers from HSE University and Brazil to Create New Theory of High Temperature Conductivity
Theoretical physicists from Russia and Brazil are working together on a theory that describes novel superconducting materials with potentially high critical temperatures. The theory can explain many properties of superconductors with non-trivial topological properties, as well as of those with multiple condensates. In this interview, Prof. Mauro Doria from the Institute of Physics at the Federal University of Rio de Janeiro, Brazil, and Prof. Alexei Vagov from the Centre for Quantum Metamaterials, MIEM HSE, talk about their cooperation.
Alexei Vagov: ‘Metamaterials Should Serve People'
The Centre for Quantum Metamaterials is one of the new international laboratories that will be launched at MIEM, HSE University, in 2022. Alexei Vagov, Head of the Centre, speaks about the main areas of the Centre’s research, its team, and future research cooperation.