A research group led by Associate Professor Atsushi Noguchi and Professor Yasunobu Nakamura, Director of RIKEN Center for Quantum Computing, has invented and successfully demonstrated a new two-qubit gating scheme that is resistant to frequency variations during superconducting qubit fabrication without the use of magnetic fields. The two-qubit gate scheme, which consists of three fixed-frequency transmon qubits and requires only indirect coupling for gate execution and is not affected by direct coupling, was confirmed to execute a controlled phase gate, a type of two-qubit gate, with an accuracy of 97.8%. The new method is expected to lead to an increase in the qubit size of superconducting quantum computers, for example, because it is resistant to frequency fluctuations during manufacturing. The paper was published in the June 29 electronic edition of the international scientific journal “Physical Review Letters”.
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