  So far, superconducting quantum computers have certain constraints on qubit
connectivity, such as nearest-neighbor couplings. To overcome this limitation,
we propose a scalable architecture to simultaneously connect several pairs of
distant qubits via a dispersively coupled quantum bus. The building-block of
the bus is composed of orthogonal coplanar waveguide resonators connected
through ancillary flux qubits working in the ultrastrong coupling regime. This
regime activates virtual processes that boost the effective qubit-qubit
interaction, which results in quantum gates on the nanosecond timescale. The
interaction is switchable and preserves the coherence of the qubits.
