Accurate Leakage Speculation for Quantum Error Correction

Abstract

Quantum Error Correction (QEC) protects qubits against bit- and phase-flip errors in the |0> or |1> subspace, but physical qubits can also leak into higher energy levels (e.g., |2>). Leakage is especially harmful, as it corrupts all subsequent syndrome measurements and can spread to neighboring qubits. Detecting leakage on data qubits is particularly challenging, since they are never measured directly during QEC cycles. Prior work, such as eraser, addresses this by inferring leakage from syndrome patterns using a fixed heuristic. However, this approach often misclassifies benign syndromes, triggering excessive leakage-reduction circuits (LRCs). Because LRCs are themselves noisy and slow, these false triggers lengthen QEC cycles and inflate logical error rates. We propose gladiator, a general and adaptable leakage speculation framework that works across surface code, color code, and qLDPC codes. Offline, gladiator builds a code-aware error-propagation graph calibrated to device data. Online, it classifies each syndrome in a few nanoseconds and schedules LRC only when the observed pattern is provably leakage-dominated. This precise speculation eliminates up to 3x (and on average 2x) unnecessary LRCs, shortens QEC cycles, and suppresses false positives at their source. Evaluated on standard fault-tolerant benchmarks, gladiator delivers 1.7x-3.9x speedups and 16% reduction in logical error rate, advancing the efficiency of fault-tolerant quantum computing.

11 pages,14 figures, MICRO '25: Proceedings of the 58th IEEE/ACM International Symposium on Microarchitecture

References in corpus (28)

• Suppressing quantum errors by scaling a surface code logical qubit
• Logical quantum processor based on reconfigurable atom arrays
• Simple pulses for elimination of leakage in weakly nonlinear qubits
• High-threshold and low-overhead fault-tolerant quantum memory
• Real-time quantum error correction beyond break-even
• Stim: a fast stabilizer circuit simulator
• Quantum Low-Density Parity-Check Codes
• Erasure conversion for fault-tolerant quantum computing in alkaline earth Rydberg atom arrays
• IBM Quantum Computers: Evolution, Performance, and Future Directions
• Universal transversal gates with color codes - a simplified approach
• Removing leakage-induced correlated errors in superconducting quantum error correction
• Quantum Error Correcting Codes Using Qudit Graph States
• Fault-tolerant error correction with the gauge color code
• Coping with qubit leakage in topological codes
• Overcoming leakage in scalable quantum error correction
• Understanding the effects of leakage in superconducting quantum error detection circuits
• Demonstrating a long-coherence dual-rail erasure qubit using tunable transmons
• All-microwave leakage reduction units for quantum error correction with superconducting transmon qubits
• A hardware-efficient leakage-reduction scheme for quantum error correction with superconducting transmon qubits
• Eliminating Leakage Errors in Hyperfine Qubits
• Leakage mitigation for quantum error correction using a mixed qubit scheme
• A Silicon Surface Code Architecture Resilient Against Leakage Errors
• Codesign of quantum error-correcting codes and modular chiplets in the presence of defects
• ERASER: Towards Adaptive Leakage Suppression for Fault-Tolerant Quantum Computing
• Enhancing Qubit Readout with Autoencoders
• Improving threshold for fault-tolerant color code quantum computing by flagged weight optimization
• Non-Pauli errors can be efficiently sampled in qudit surface codes
• Synchronization for Fault-Tolerant Quantum Computers