MOSCOW, November 20, Vladislav Strekopytov. The quantum Internet should play a decisive role in the widespread introduction of quantum technologies, says physicist Alexey Fedorov. In an interview, he explained what prospects the new communication tool opens up and what is needed to launch it.
The first quantum revolution is the period of explosive technological growth that followed the creation of quantum physics. The result was the transistor and laser technology, and later consumer computers and other digital devices. It is believed that today we are on the threshold of the second quantum revolution. One of its key tasks is the development of a universal quantum computer capable of performing calculations that are inaccessible to existing technology.
The difficulty lies in the fact that for this it is necessary to create a system that has, at first glance, incompatible properties. On the one hand, a quantum computer must be large enough to process enormous amounts of data. On the other hand, an increase in size should not lead to a loss of quantum properties. To do this, you need to maintain a high level of control over the quantum system.
The solution, according to scientists, could be the creation of devices based on the concept of the quantum Internet. This approach makes it possible to increase the power of quantum computers by connecting them into quantum networks without reducing the level of control in each of them.
— Alexey Konstantinovich, what are quantum computers for and why should they be connected to each other?
— A quantum computer is needed to solve problems in the field of cryptography, quantum chemistry, optimization of financial modeling, training of artificial intelligence, which classical computers and even supercomputers that are familiar to us cannot cope with. Using quantum algorithms, you can calculate the parameters of complex molecules, drugs, and new materials — for example, for aircraft manufacturing.
If hundreds and thousands of qubits are enough to solve initial problems, then hundreds of thousands or millions are needed to demonstrate the significant advantages of quantum devices. High precision quantum operations are also required. Therefore, the main problem is to scale quantum computing without losing the quality of control over the qubits. One option is to network intermediate-scale quantum processors.
— What are the benefits of a quantum internet?
“It allows you to increase power not only by increasing the number of qubits in each individual processor, but also by connecting them to each other. With this configuration, the processor will consist of several “quantum hubs” connected by quantum communications based on the transfer of quantum states. The fact is that when connected to a network, the powers of classical computers add up, and those of quantum computers are multiplied. This provides a colossal resource for solving computational problems.
— Is it already possible to use the quantum Internet?
— Not yet. In 2021, there were several striking experiments that demonstrated the basic principles of its operation, including for modular superconducting devices. Further progress in this area is extremely important. Therefore, the strategic project “Quantum Internet” was included in the development program of NUST MISIS for 2021-2030.
It connects two main vectors of development of quantum technologies — quantum computing and quantum communications. The university is successfully working in these areas. In the laboratory «Superconductor Quantum Technologies», which has become the core of our Institute of Physics and Quantum Engineering, they create quantum devices based on superconducting qubits and implement a microwave channel for transmitting quantum information between them, and the NTI Center «Quantum Communications» is responsible for technologies for quantum data transmission and their systems protection.
— That is, for the quantum Internet to work, special hardware and data transmission technologies are required?
— Not only. The accumulated experience of classical telecommunications cannot always be directly used in quantum networks, and therefore separate studies are required. We need new algorithms for quantum software, special protocols for communicating quantum computers, and new architectures for quantum computing devices. The dynamics of complex quantum systems and the transfer of information within them remain to be studied. As part of the Quantum Internet project, we are not only working directly on the implementation of a channel for transmitting quantum information from one qubit to another, but also creating new protocols for generating entangled states, as well as algorithms for solving prototypes of applied problems in the field of chemistry and optimization.
— What is the operating principle of existing quantum processors based on?
— There are several ways to create them. One is the use of superconducting Josephson junctions and microscopic superconducting structures. This approach has been adopted by many industrial leaders such as Google, IBM and Alibaba. The key advantage of the superconductor version of the development of quantum devices is their manufacturability. These devices are created using well-developed lithography technology. They combine high speed and quality of quantum operations. But there are also difficulties — for example, the requirement for a high degree of identity of superconducting qubits.
In addition to superconducting quantum processors, other platforms are also being developed — neutral atoms, ions, optical qubits. We actively cooperate with scientific groups working in these areas. However, each of the mentioned platforms faces the problem of maintaining the quality of control as the number of qubits increases. 16-qubit processors based on ions and neutral atoms have already been demonstrated in Russia. Apparently, the number of controlled ion qubits in the trap and neutral atoms can be increased to 50-100. Scientific groups around the world have conducted experiments with 256-atomic qubits, but the quality of operations in this case is significantly lower than in the version with ions. Recently announced superconducting processors from IBM have 127 and 433 qubits, but in the first case the quality of operations does not allow solving problems faster than a classical computer, and the detailed parameters of the 433-qubit processor are still unknown.
— How can you optimize the operation of quantum processors?
— There are several approaches. For example, creating new types of qubits. Most processors in the world use the so-called transmon architecture (superconducting charge qubit. — Ed.). Our colleagues at the RCC and the Laboratory of Superconducting Quantum Technologies MISIS, together with colleagues from MIPT, VNIIA named after. N.L. Dukhov and MSTU named after. N. E. Bauman are also working with a new promising qubit with high quality quantum operations — flaxonium.
We are also exploring the possibility of using qudits — multi-level quantum systems that allow information to be encoded «more densely». This approach helps to implement quantum algorithms more efficiently. We have already tried to use three-level qudits, the so-called qutrits, to analyze such physical phenomena as phase transitions.
— What direction of quantum technologies, in your opinion, will receive the greatest development in the near future?< br />“We can assume that as part of the development of existing platforms, we will soon see limits to scaling. It is not yet clear whether these limits are fundamental in nature and how much further it can be advanced, but it is clear that new ideas are needed. One of them is the creation of networks of interconnected quantum processors. This approach is promising for all physical platforms of quantum computing, so I believe that bright scientific and practical results in this direction await us.
Russia has adopted two roadmaps — on quantum computing and quantum communications. We are actively involved in the implementation of both. The stated goal of the quantum computing roadmap is to scale quantum processors by increasing the number of qubits and the quality of quantum operations. One of the tools for achieving this could be the quantum Internet.
January 8, 08:00
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