NNSU named after Lobachevsky and Moscow State University Lomonosov: Hybrid system for managing quantum states

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2025: Announcement of the approach to creating a quantum interface for data transmission based on superconducting structures operating in qubit mode

Scientists proposed a promising approach to creating a quantum interface for transmission data based on superconducting structures operating in the mode - qubits basic elements. quantum computer Superconducting structures are capable of operating in two modes: stationary - when they store are processed - and in information the mode of the so-called "flying" qubits transmitting along the data chain. The authors simulated a system for controlling such qubits using magnetic flux pulses, which avoided loss of information during transmission between elements. This approach paves the way for compact energy efficient and quantum processors for quantum communication problems artificial intelligence , and complex calculations that are technically inaccessible to. usual computers The results of the study, supported by the grant, Russian Science Foundation (RSF) are published in the journal Chaos, Solitons and Fractals. This was announced on May 6, 2025 by the press service of the scientific Russian foundation.

As reported, quantum computers will solve problems that are not available even to the most powerful classical supercomputers - from modeling complex molecules to optimizing large-scale logistics systems. However, their main limitation remains the problem of quantum communication: qubits are extremely sensitive to external influences and easily lose their properties (in particular, the ability to be simultaneously in two states - conditionally "0" and "1").

In 2025, microwave superconducting resonators, structures that help qubits "communicate" with electromagnetic waves, are used to transmit quantum information. Such systems turn out to be technically quite complex, and cannot be miniaturized. In addition, as the number of qubits increases, crosstalk occurs in the system - situations where signals from neighboring resonators overlap each other, distorting the transmitted information. This leads to errors in quantum operations and requires complex customization of each element, making the system virtually non-scalable. Therefore, scientists are looking for other technologies to control qubits and transfer quantum states.

Researchers from Nizhny Novgorod State University named after N.I. Lobachevsky (Nizhny Novgorod) and Moscow State University named after M.V. Lomonosov (Moscow) modeled a hybrid system based on superconducting elements - adiabatic quantum parametrons - to control quantum states. A system based on an adiabatic cell (parametron) is a device through which current flows when an external magnetic field acts on it. When cooled to cryogenic temperatures (near to absolute zero) the system operates in quantum mode. In this case, the current can circulate stably either clockwise (conditionally quantum state "0") or counter (quantum state "1"). In addition, each element of the system (parametron) can be in a superposition of both states at the same time - this allows them to be used as qubits. These stationary states can be preserved for a long time, and therefore used to store quantum information.

However, the elements of the system are able not only to store, but also to transmit information. In this case, the adiabatic quantum parametron transitions from a steady state with a constantly flowing current to the mode of the so-called "flying" qubit transmitting data. This is due to the fact that instead of static (DC) current between the elements, a dynamic switching wave occurs, sequentially propagating along the chain. Each such switching leads to a consistent change in the direction of current in neighboring elements - from "0" to "1" or vice versa. As a result, the entire system can be compared to a falling domino - each next chip, when dropped, "repeats" the state of the previous one. At the same time, the pulse transmitted along such a chain itself retains its shape and energy, which makes the transmission of information resistant to interference.

A key possibility of this approach is that just one physical process - the circulation of a superconducting current under the influence of a magnetic field - provides both stationary storage and transmission of quantum states. Transition between modes is performed through precise control of external magnetic field. At the same time, adiabatic quantum parametrons have a value of tens or hundreds of micrometers, due to which they turn out to be smaller than standard microwave resonators, the dimensions of which range from hundreds of micrometers to millimeters.

The developed energy efficient and compact system with "flying" qubits will accelerate the transition to the practical use of quantum technologies. It will help reduce cost and optimize the scaling of computing systems, which paves the way for compact solutions for the transmission and processing of quantum information. In addition, the results of the study can be useful in creating quantum-neuromorphic hybrid computing and telecommunications systems, where the power of both neuromorphic (based on neural networks) and quantum approaches to information processing is used for calculations. told Marina Bastrakova, project manager supported by a grant from the Russian National Research Institute, candidate of physical and mathematical sciences, associate professor of the department of theoretical physics, head of the laboratory of nanostructure theory of Nizhny Novgorod State University named after N.I. Lobachevsky

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Фото: Marie

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Фото: Marie