Improved error correction with leakage reduction units built into qubit measurement in a superconducting quantum processor
quant-ph
Submitted: 2025-11-21
Updated: 2025-11-21
Comments: 18 pages, 13 figures
DOI: 10.1103/y66v-988s
Code: https://github.com/MarcSerraPeralta/data-lru-integrated-with-measurement-for-qec
License: http://creativecommons.org/licenses/by/4.0/
The gist: Leakage to non-computational states is a source of correlated errors in both time and space that limits the effectiveness of quantum error correction (QEC) with superconducting circuits.
Terminology
Abstract
Leakage to non-computational states is a source of correlated errors in both time and space that limits the effectiveness of quantum error correction (QEC) with superconducting circuits. We present and experimentally demonstrate a high-fidelity, leakage reduction unit (LRU) operating concurrently with transmon measurement without incurring time overhead. Adapted from double-drive reset of population (DDROP), the protocol utilizes simultaneous drives on the transmon and its readout resonator, leveraging the dispersive shift to create a directional process that returns the transmon to the computational subspace. The LRU achieves a 98.4% leakage removal fraction without compromising the computational-state assignment fidelity (99.2%). We combine LRU-enhanced measurement and neural-network decoding to successfully suppress logical error rates in both memory and stability QEC experiments without any post-selection.
Sources
- Fault-Tolerant Operation of a Quantum Error-Correction Code
- Leakage Mobility in Superconducting Qubits as a Leakage Reduction Unit
- High-fidelity gates in a transmon using bath engineering for passive leakage reset
- Fast unconditional reset and leakage reduction in fixed-frequency transmon qubits
- Flexible Readout and Unconditional Reset for Superconducting Multi-Qubit Processors with Tunable Purcell Filters
- Improved iterative Bayesian unfolding
- Demonstrating real-time and low-latency quantum error correction with superconducting qubits
- Characterising the failure mechanisms of error-corrected quantum logic gates
- Importance sampling for data-driven decoding of quantum error-correcting codes
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