Low Overhead Quantum Bus with Coupling beyond the Nearest Neighbor via Mediated Effective Capacitance

Abstract

The design of easy to operate high-fidelity two qubit gates remains an area of ongoing research. Many of the common schemes require dedicated controls lines, while others are vulnerable to issues of frequency crowding. Here, we propose a scheme for coupling a chain of transmons acting as logical qubits via a quantum bus of auxiliary qubits. The auxiliary array is made of floating transmons, and through the use of mediated interactions we generate effective capacitance between them beyond the nearest neighbor. Logical qubits are not directly coupled to each other, but they can be coupled by bringing them closer in frequency to the far-detuned auxiliary arrays. This allows for tunable coupling between non-neighboring logical qubits, and for the application of entangling gates to three or more qubits at once.

11 pages, 6 figures

References in corpus (6)

• Supplementary information for "Quantum supremacy using a programmable superconducting processor"
• Charge insensitive qubit design derived from the Cooper pair box
• QuTiP 2: A Python framework for the dynamics of open quantum systems
• A scalable superconducting quantum simulator with long-range connectivity based on a photonic bandgap metamaterial
• Simplified Josephson-junction fabrication process for reproducibly high-performance superconducting qubits
• Switchable coupling for superconducting qubits using double resonance in the presence of crosstalk