Low-loss interconnects for modular superconducting quantum processors

Abstract

Scaling is now a key challenge in superconducting quantum computing. One solution is to build modular systems in which smaller-scale quantum modules are individually constructed and calibrated, and then assembled into a larger architecture. This, however, requires the development of suitable interconnects. Here, we report low-loss interconnects based on pure aluminium coaxial cables and on-chip impedance transformers featuring quality factors up to $8.1\times 10^5$, which is comparable to the performance of our transmon qubits fabricated on single-crystal sapphire substrate. We use these interconnects to link five quantum modules with inter-module quantum state transfer and Bell state fidelities up to 99\%. To benchmark the overall performance of the processor, we create maximally-entangled, multi-qubit Greenberger-Horne-Zeilinger (GHZ) states. The generated inter-module four-qubit GHZ state exhibits 92.0\% fidelity. We also entangle up to 12 qubits in a GHZ state with $55.8\pm 1.8\%$ fidelity, which is above the genuine multipartite entanglement threshold of 1/2. These results represent a viable modular approach for large-scale superconducting quantum processors.

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• Long-Range Quantum Tunneling via Matter Wave
• Generation of Frequency-Tunable Shaped Single Microwave Photons Using a Fixed-Frequency Superconducting Qubit
• Distributed multi-parameter quantum metrology with a superconducting quantum network
• Joint Wire Cutting with Non-Maximally Entangled States
• The simulation of distributed quantum algorithms
• Flying-cat parity checks for quantum error correction
• Resource-Efficient Cross-Platform Verification with Modular Superconducting Devices
• On-demand shaped photon emission based on a parametrically modulated qubit
• Low-loss liquid metal interconnects for superconducting quantum circuits
• Mitigating cosmic ray-like correlated events with a modular quantum processor
• Multimode Purcell Filter for Superconducting-Qubit Reset and Readout with Intrinsic Purcell Protection
• Integrating planar circuits with superconducting 3D microwave cavities using tunable low-loss couplers
• Fat-Tree QRAM: A High-Bandwidth Shared Quantum Random Access Memory for Parallel Queries
• Tunable Hybrid-Mode Coupler Enabling Strong Interactions between Transmons at Centimeter-Scale Distance
• Channel capacity of small modular quantum networks in the ultrastrongly coupled regime
• Scalable Low-overhead Superconducting Non-local Coupler with Exponentially Enhanced Connectivity
• Time-delayed collective dynamics in waveguide QED and bosonic quantum networks
• High-performance quantum interconnect between bosonic modules beyond transmission loss constraints
• Deterministic Quantum Communication Between Fixed-Frequency Superconducting Qubits via Broadband Resonators
• Remote entanglement generation via enhanced quantum state transfer