Building Blocks for Modular Circuit QED Quantum Computing

The ability to couple isolated quantum systems demonstrates precise and powerful control over natural phenomena. It can be of use in quantum information by connecting systems in a modular network to realize distributed, fault-tolerant quantum computing. This requires highly performing modules and efficient communication channels. Here, we describe integrated state-of-the-art hardware in circuit quantum electrodynamics intended to produce such an elementary module. We explore the dissipation mechanisms that limit their fundamental performance and demonstrate a method to transmit quantum information from a module, via propagating photons, into another module. State transfer and entanglement are both realized with high fidelity. These results establish a compelling approach for deterministic, network-based quantum computation, and may serve as the basis for how superconducting quantum circuits can be scaled to even greater numbers.