Logical multi-qubit entanglement with dual-rail superconducting qubits
arXiv:2504.12099 · doi:10.1038/s41567-026-03211-9
Abstract
Recent advances in quantum error correction (QEC) across hardware platforms have demonstrated operation near and beyond the fault-tolerance threshold, yet achieving exponential suppression of logical errors through code scaling remains a critical challenge. Erasure qubits, which enable hardware-level detection of dominant error types, offer a promising path toward resource-efficient QEC by exploiting error bias. Single erasure qubits with dual-rail encoding in superconducting cavities and transmons have demonstrated high coherence and low single-qubit gate errors with mid-circuit erasure detection, but the generation of multi-qubit entanglement--a fundamental requirement for quantum computation and error correction--has remained an outstanding milestone. Here, we demonstrate a superconducting processor integrating four dual-rail erasure qubits that achieves the logical multi-qubit entanglement with error-biased protection. Each dual-rail qubit, encoded in pairs of tunable transmons, preserves millisecond-scale coherence times and single-qubit gate errors at the level of . By engineering tunable couplings between logical qubits, we generate high-fidelity entangled states resilient to physical qubit noise, including logical Bell states (98.8% fidelity) and a three-logical-qubit Greenberger-Horne-Zeilinger (GHZ) state (93.5% fidelity). A universal gate set is realized through a calibrated logical controlled-NOT (CNOT) gate with 96.2% process fidelity, enabled by coupler-activated interactions in the protected logical subspace. This work advances dual-rail architectures beyond single-qubit demonstrations, providing a blueprint for concatenated quantum error correction with erasure qubits.
References in corpus (36)
- Quantum sensing
- Charge insensitive qubit design derived from the Cooper pair box
- Quantum Error Correction for Quantum Memories
- Suppressing quantum errors by scaling a surface code logical qubit
- Logical quantum processor based on reconfigurable atom arrays
- Quantum metrology from a quantum information science perspective
- Robust randomized benchmarking of quantum processes
- Quantum error correction below the surface code threshold
- Dynamically protected cat-qubits: a new paradigm for universal quantum computation
- Demonstration of multi-qubit entanglement and algorithms on a programmable neutral atom quantum computer
- High-fidelity parallel entangling gates on a neutral atom quantum computer
- Efficient measurement of quantum gate error by interleaved randomized benchmarking
- Quantum control of surface acoustic wave phonons
- Real-time quantum error correction beyond break-even
- A tunable coupling scheme for implementing high-fidelity two-qubit gates
- Exponential suppression of bit or phase flip errors with repetitive error correction
- Demonstration of fault-tolerant universal quantum gate operations
- High-fidelity gates with mid-circuit erasure conversion in a metastable neutral atom qubit
- State tomography of capacitively shunted phase qubits with high fidelity
- Erasure conversion for fault-tolerant quantum computing in alkaline earth Rydberg atom arrays
- High-fidelity, high-scalability two-qubit gate scheme for superconducting qubits
- Deterministic multi-qubit entanglement in a quantum network
- Fault-tolerant quantum computation against biased noise
- Bias-preserving gates with stabilized cat qubits
- Beating the break-even point with a discrete-variable-encoded logical qubit
- Rotating-frame relaxation as a noise spectrum analyzer of a superconducting qubit undergoing driven evolution
- Entangling logical qubits with lattice surgery
- Low-loss interconnects for modular superconducting quantum processors
- Error-corrected gates on an encoded qubit
- Quantum Error Correction with Metastable States of Trapped Ions Using Erasure Conversion
- Direct Characterization of Quantum Dynamics: General Theory
- Dephasing-insensitive quantum information storage and processing with superconducting qubits
- Deterministic quantum teleportation between distant superconducting chips
- Tailored XZZX codes for biased noise
- Semiconductor-inspired design principles for superconducting quantum computing
- Coupler-Assisted Leakage Reduction for Scalable Quantum Error Correction with Superconducting Qubits