So far, superconducting quantum computers have certain constraints on qubit connectivity, such as nearest-neighbor couplings. To overcome this limitation, a team of researchers at RIKEN, Japan, has proposed 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.
The paper has been published in npj Quantum Information.