RCC: Error correction method on superconducting quantum processors

The main articles are:

• Quantum computer and quantum communication
• Quantum computers and networks in Russia

2023: Approach Development

Scientists from the Russian Quantum Center have developed an approach that allows you to implement error correction codes on quantum processors that do not have high computing power. The results will help physicists reduce noise exposure and approach practical problems on systems with relatively few qubits. The center announced this on March 30, 2023.

The solution to the problem on a quantum computer can be presented in the form of three stages: the preparation of the register of a quantum device, the manipulation of the system and the final reading of the measurements obtained. The main obstacle at each stage is a high noise level, which does not allow maintaining the desired state of quantum objects long enough for practical algorithms to work. That is why reducing the level of errors is a priority area of ​ ​ research for scientists.

The idea of ​ ​ error correction codes is to encode a logical qubit that is resistant to external noise in a large number of physical qubits. However, for the logic qubit to work, the system also needs to use auxiliary qubits - ancilli. Intermediate measurements of the ancillas allow you to track the effect of noise on the state of the logical qubit. Scientists from the Russian Quantum Center have proposed an approach to implementing an extensive class of error correction codes, which allows you to reduce the number of auxiliary qubits to one, as well as use the specifics of superconducting quantum processors to reduce the influence of noise.

The researchers proved that this class of quantum error correction codes can be implemented with a fairly simple structure - circular connectivity of neighboring qubits. Thus, the new approach allows you to abandon operations between "far" located qubits from each other in favor of two neighboring ones. The efficiency of the circuit is demonstrated by executing a three-cube repetition code, a five-cube Laflamme error correction code, and a nine-cube Shore code. Also, the work proposes a method of implementing a surface error correction code using one ancilla-qubit and qubit connectivity with nearest neighbors.

The proposed approach turned out to be applicable to a rather large class of quantum correction codes, which makes it promising for use in experiments with superconducting quantum processors, "said Anatoly Antipov, co-author of the study, researcher at the Quantum Information Technologies group of the Russian Quantum Center.