![]() ![]() However, these technologies impose other difficulties in qubits designs and damage the future scalability of quantum computers. Massive efforts have been paid to make superconducting qubits insensitive to cosmic rays, e.g., shielding qubits. While similar effects are known in the classical memory cells as soft errors, their quantum counterpart affects a vast region and lasts longer since qubits are fragile to environmental noise. For example, in the case of superconducting qubits, cosmic rays hit the substrate of quantum chips with a small probability and incur a burst error on multiple qubits. However, these experiments also reveal that temporal error-property changes are inevitable and degrade the performance of QEC schemes (Fig. Recent technological progress enables the integration of a large number of qubits, and logical-error reduction is experimentally demonstrated in superconducting circuits. (Figure 1) Schematic picture of quantum error correction Therefore, surface codes are considered promising in a variety of quantum devices, such as superconducting circuits, trapped ions, quantum dots, neutral atoms, and photons. Surface codes are the most promising quantum error-correcting codes since they can be implemented with qubits integrated on two-dimensional grids, and error-estimation problems can be converted to efficiently solvable graph-matching problems with small approximations (Fig. By estimating what errors occur on the qubits from the syndrome values with classical computers, we can efficiently track and eliminate the effect of errors on quantum computers. During the computation, we repeatedly check the error parities, called syndrome values. In typical QEC schemes, several noisy physical qubits are encoded to form a fewer number of logical qubits. One of the most promising methods for achieving reliable quantum computation is quantum error correction (QEC). This means that unexpected leakage of the information from the qubits to an environment is treated as an error, and thus qubits are fragile to environmental noise compared to classical ones. Once we observe the state of qubits, the superposition states are probabilistically collapsed to either zero or one. An element of quantum computers is called a qubit, which can be a superposition of binary states. The main challenge in the development is the reduction of high error rates in quantum computers. Thus, many groups are working on developing large and reliable quantum computers. Quantum computers are expected to be capable of efficiently solving scientifically important problems, such as prime factoring and quantum chemistry. ![]() Nippon Telegraph and Telephone Corporation (Chiyoda-ku, Tokyo President: Akira Shimada), Kyushu University (Fukuoka-shi, Fukuoka President: Tatsuro Ishibashi), and the University of Tokyo (Bunkyo-ku, Tokyo President: Teruo Fujii) have developed the world's first quantum computer architecture that significantly reduces the effect of burst errors, which is known to be one of the most urgent problems in the scalability of quantum computers, by changing the error-correction strategies adaptively to the error properties of quantum computers. ![]()
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