A modular quantum computer based on a parametrically driven quantum state router*

For superconducting quantum computers, most efforts seek to implement a “surface code” architecture, which only couples nearest-neighbor qubits. In such a computer, operations between distant qubits require a large number of nearest-neighbor gates to implement with concomitant increases in gate errors and run time. In contrast, a modular architecture allows for long-range couplings between distant qubits. We have realized a modular quantum state router based on three-wave couplings with all-to-all couplings between 4 modules. We have connected the router to four simple modules consisting of a high Q communication cavity which couples to the router, a single transmon qubit and a readout cavity to demonstrate feasibility of operating the router + module systems as a quantum machine. In this talk, we will demonstrate basic operations in our machine: transferring states and generating entanglement among the modules’ communication modes and qubits. Furthermore, we will discuss the potential for utilizing ancillary modes in the router as ancillary quantum storage, as well as expanding the router system to form a large scale quantum router for an arbitrary number of modules.