Inter-chip entanglement of superconducting quantum circuits
Abstract: Reliable quantum computers will depend on the ability to connect a large number of qubits. For solid-state quantum devices, this will most likely require high-fidelity entanglement across multiple chips. A challenge with these inter-chip gates is the high loss inflicted on them when travelling between the separated qubits. This loss will strongly depend on the quality of the communication channel connecting the chips. We pursue a modular, high-Q hardware scheme for performing gates between superconducting transmon qubits on separated chips. We have engineered a low loss, de-mateable superconducting cable connection that we aim to use as a ‘quantum bus’. Combined with parametric drives, this approach can achieve high fidelity gates between the remote qubits, for instance through driving a virtual Raman process. Based off measurements of the necessary parameters in our network, our data suggests that a gate infidelity below 1% in less than a microsecond is within reach. Our inter-chip connection design could thus serve as a key component in a modular, multi-wafer superconducting quantum computer.
