Multi-mode superconducting circuits for realizing strongly coupled multi-qubit processor units

Abstract

Inter-qubit coupling and qubit connectivity in a processor are crucial for achieving high fidelity multi-qubit gates and efficient implementation of quantum algorithms. Typical superconducting processors employ relatively weak transverse inter-qubit coupling which are activated via frequency tuning or microwave drives. Here, we propose a class of multi-mode superconducting circuits which realize multiple transmon qubits with all-to-all longitudinal coupling. These "artificial molecules" directly implement a multi-dimensional Hilbert space that can be easily manipulated due to the always-on longitudinal coupling. We describe the basic technique to analyze such circuits, compute the relevant properties and discuss how to optimize them to create efficient small-scale quantum processors with universal programmability.

16 pages, 12 figures; Revised version with three new sections and updated references

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Cited by in corpus (8)

• Understanding the saturation power of Josephson Parametric Amplifiers made from SQUIDs arrays
• A programmable three-qubit superconducting processor with all-to-all connectivity
• Scalable and Robust Photonic Integrated Unitary Converter
• Engineering Cross Resonance Interaction in Multi-modal Quantum Circuits
• Efficient decoupling of a non-linear qubit mode from its environment
• Characterization, synthesis, and optimization of quantum circuits over multiple-control $\text{Z}$-rotation gates: A systematic study
• Transmon-qubit readout using in-situ bifurcation amplification in the mesoscopic regime
• Characterisation of spatial charge sensitivity in a multi-mode superconducting qubit