Modular Tunable Coupler for Superconducting Circuits

The development of modular and versatile quantum interconnect hardware is a key next step in the scaling information platforms to larger size greater functionality. For superconducting systems, fast well-controlled tunable circuit couplers will be paramount for achieving high-fidelity resource-efficient connectivity, whether performing two-qubit gate operations, encoding or decoding data bus, interfacing across modalities. Here we propose internally double-transmon coupler (DTC) architecture that implements coupling via flux-controlled interference three-junction dc device. Crucially, DTC possesses an defined zero-coupling state independent coupled qubits resonators. This makes it particularly attractive as design element realizing robust linear several applications such qubit readout, bus interfacing.