Researchers from the RIKEN Center for Quantum Computing and Toshiba have succeeded in building a quantum computer gate based on a double-transmon coupler (DTC), which had been proposed theoretically by Hayato Goto, Senior Fellow at Toshiba, as a device that could significantly enhance the fidelity of quantum gates. Using this, they achieved a fidelity of 99.90 percent for a two-qubit device known as a CZ gate and 99.98 percent for a single-qubit gate. This breakthrough, which was carried out as part of the Q-LEAP project, not only boosts the performance of existing noisy intermediate-scale quantum (NISQ) devices but also helps pave the way for the realization of fault-tolerant quantum computation through effective quantum error correction.