Demonstration of Logical Error Suppression in a Surface Code Memory on a Cloud-Accessible IBM Superconducting Processor

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Closest papers

1. Very close Cited by this paper Not relevant

   Quantum error correction below the surface code threshold

   R. Acharya, D. Abanin, Laleh Aghababaie-Beni et al. · 2024 · Nature · Not summarized yet

   Abstract

   Quantum error correction1, 2, 3–4 provides a path to reach practical quantum computing by combining multiple physical qubits into a logical qubit, in which the logical error rate is suppressed exponentially as more qubits are added. However, this exponential suppression only occurs if the physical error rate is below a critical threshold. Here we present two below-threshold surface code memories on our newest generation of superconducting processors, Willow: a distance-7 code and a distance-5 code integrated with a real-time decoder. The logical error rate of our larger quantum memory is suppressed by a factor of Λ = 2.14 ± 0.02 when increasing the code distance by 2, culminating in a 101-qu…

2. Very close Cited by this paper Not relevant

   Suppressing quantum errors by scaling a surface code logical qubit

   R. Acharya, I. Aleiner, R. Allen et al. · 2022 · Nature · Not summarized yet

   Abstract

   Practical quantum computing will require error rates well below those achievable with physical qubits. Quantum error correction^ 1 , 2 offers a path to algorithmically relevant error rates by encoding logical qubits within many physical qubits, for which increasing the number of physical qubits enhances protection against physical errors. However, introducing more qubits also increases the number of error sources, so the density of errors must be sufficiently low for logical performance to improve with increasing code size. Here we report the measurement of logical qubit performance scaling across several code sizes, and demonstrate that our system of superconducting qubits has sufficient pe…

3. Very close Cited by this paper Not relevant

   Removing leakage-induced correlated errors in superconducting quantum error correction

   M. McEwen, D. Kafri, Z. Chen et al. · 2021 · Nature Communications · Not summarized yet

   Abstract

   Quantum computing can become scalable through error correction, but logical error rates only decrease with system size when physical errors are sufficiently uncorrelated. During computation, unused high energy levels of the qubits can become excited, creating leakage states that are long-lived and mobile. Particularly for superconducting transmon qubits, this leakage opens a path to errors that are correlated in space and time. Here, we report a reset protocol that returns a qubit to the ground state from all relevant higher level states. We test its performance with the bit-flip stabilizer code, a simplified version of the surface code for quantum error correction. We investigate the accumu…

4. Very close Not relevant

   Error-Corrected Memory and Logic on a Heavy-Hex Superconducting-Qubit Processor

   Campbell K. McLauchlan, Georgia M. Nixon, Julien M. Drouet et al. · 2026 · Not summarized yet

   Abstract

   Large quantum computations require high-fidelity error-corrected memory and fault-tolerant logical operations. To achieve these with superconducting circuits, quantum processors will need many components operating with low error rates. In practice, fabrication of monolithic superconducting devices produces unavoidable heterogeneity in component performance, which the quantum computer must accommodate. We implement strategies to operate a large dynamic compass code on an array of 156 superconducting qubits arranged on a heavy-hexagonal lattice, making use of the entire monolithic quantum processor and redesigning our measurement schedule to exclude underperforming components. We demonstrate i…

5. Very close Cited by this paper Not relevant

   Error correction on an array of superconducting qubits with defective components

   Julien M. Drouet, X. C. Kolesnikow, Campbell K. McLauchlan et al. · 2026 · Not summarized yet

   Abstract

   A solid-state quantum-computing architecture will require the fabrication of arrays of many coupled qubits. It is inevitable that this process will produce qubits and couplers with varying performance, with some components underperforming due to imperfect fabrication. Quantum error-correction requires high-performing components and hence these defects must be dealt with, either by adapting the code to exclude the defects, or by informing the decoder to accommodate defects in post-processing. Here we implement and compare strategies to operate distance-5 surface codes on a quantum processor consisting of a square-lattice array of 120 superconducting qubits. We demonstrate a dramatic reduction…

6. Very close Cited by this paper Not relevant

   Surface code error correction on a defective lattice

   S. Nagayama, A. Fowler, Dominic C. Horsman et al. · 2016 · New Journal of Physics · Not summarized yet

   Abstract

   The yield of physical qubits fabricated in the laboratory is much lower than that of classical transistors in production semiconductor fabrication. Actual implementations of quantum computers will be susceptible to loss in the form of physically faulty qubits. Though these physical faults must negatively affect the computation, we can deal with them by adapting error-correction schemes. In this paper we have simulated statically placed single-fault lattices and lattices with randomly placed faults at functional qubit yields of 80%, 90%, and 95%, showing practical performance of a defective surface code by employing actual circuit constructions and realistic errors on every gate, including id…

7. Very close Cited by this paper Not relevant

   Analysis of Surface Code Algorithms on Quantum Hardware Using the Qrisp Framework

   Jan Krzyszkowski, Marcin Niemiec · 2025 · Electronics · Not summarized yet

   Abstract

   The pursuit of scalable quantum computing is intrinsically limited by qubit decoherence, making robust quantum error correction (QEC) techniques crucial. As a leading solution, the topological surface code offers inherent protection against local noise. This study presents the first comprehensive implementation and quantitative characterization of a full surface code pipeline, which includes encompassing lattice construction, multi-round syndrome extraction, and MWPM decoding, using the high-level Qrisp programming framework. The entire pipeline was executed on IQM superconducting quantum processors to provide an empirical assessment under current noisy intermediate-scale quantum (NISQ) cond…

8. Very close Cited by this paper Not relevant

   Realization of an Error-Correcting Surface Code with Superconducting Qubits.

   You-Wei Zhao, Yang-Sen Ye, He-Liang Huang et al. · 2021 · Physical Review Letters · Not summarized yet

   Abstract

   Quantum error correction is a critical technique for transitioning from noisy intermediate-scale quantum devices to fully fledged quantum computers. The surface code, which has a high threshold error rate, is the leading quantum error correction code for two-dimensional grid architecture. So far, the repeated error correction capability of the surface code has not been realized experimentally. Here, we experimentally implement an error-correcting surface code, the distance-three surface code which consists of 17 qubits, on the Zuchongzhi 2.1 superconducting quantum processor. By executing several consecutive error correction cycles, the logical error can be significantly reduced after applyi…

Prior work it builds on

1. Very close Not relevant

   Optimal complexity correction of correlated errors in the surface code

   A. Fowler · 2013 · arXiv: Quantum Physics · Not summarized yet

   Abstract

   Centre for Quantum Computation and Communication Technology,School of Physics, The University of Melbourne, Victoria 3010, Australia(Dated: December 16, 2013)The surface code is designed to suppress errors in quantum computing hardware and currentlyo ers the most believable pathway to large-scale quantum computation. The surface code requiresa 2-D array of nearest-neighbor coupled qubits that are capable of implementing a universal set ofgates with error rates below approximately 1%, requirements compatible with experimental reality.Consequently, a number of authors are attempting to squeeze additional performance out of thesurface code. We describe an optimal complexity error suppression al…

2. Very close Not relevant

   Demonstration of dynamic surface codes

   A. Eickbusch, M. McEwen, V. Sivak et al. · 2025 · Nature Physics · Not summarized yet

   Abstract

   A remarkable characteristic of quantum computing is the potential for reliable computation despite faulty qubits. This can be achieved through quantum error correction, which is typically implemented by repeatedly applying static syndrome checks, permitting correction of logical information. Recently, the development of time-dynamic approaches to error correction has enabled different codes and implementations that do not rely on static syndrome measurements. Here we experimentally demonstrate three time-dynamic implementations of the surface code, each offering a distinct solution to hardware design challenges faced by surface code realizations. First, we embed the surface code on a hexagon…

3. Very close Not relevant

   Experiments with the four-dimensional surface code on a quantum charge-coupled device quantum computer

   Noah F. Berthusen, J. Dreiling, C. Foltz et al. · 2024 · Physical Review A · Not summarized yet

   Abstract

   Single-shot quantum error correction has the potential to speed up quantum computations by removing the need for multiple rounds of syndrome extraction in order to be fault-tolerant. Using Quantinuum's H2 trapped-ion quantum computer, we implement the [[33,1,4]] 4D surface code and perform the first experimental demonstration of single-shot quantum error correction with bare ancilla qubits. We conduct memory experiments comparing the 2D and 4D surface codes and find that despite differences in qubit use and syndrome extraction circuit depth, the 4D surface code matches or outperforms the 2D surface code in both the fault-tolerant and single-shot regimes.

4. Very close Not relevant

   Characterising the failure mechanisms of error-corrected quantum logic gates

   Robin Harper, C. Lain'e, Evan T. Hockings et al. · 2025 · Nature Communications · Not summarized yet

   Abstract

   Mid-circuit measurements used in quantum error correction are essential in the architecture of a fault-tolerant quantum computer, as they read out syndrome data and drive logic gates. Here, we use a heavy-hex code prepared on a superconducting qubit array to investigate how different noise sources impact error-corrected logic. First, we identify that idling errors occurring during readout periods are highly detrimental to a quantum memory. We demonstrate significant improvements to the memory by designing and implementing a low-depth syndrome extraction circuit. Second, we perform a stability experiment to investigate the type of failures that can occur during logic gates due to readout assi…

5. Very close Not relevant

   Fault-Tolerant Logical Gates in the IBM Quantum Experience.

   R. Harper, S. Flammia · 2018 · Physical Review Letters · Not summarized yet

   Abstract

   Quantum computers will require encoding of quantum information to protect them from noise. Fault-tolerant quantum computing architectures illustrate how this might be done but have not yet shown a conclusive practical advantage. Here we demonstrate that a small but useful error detecting code improves the fidelity of the fault-tolerant gates implemented in the code space as compared to the fidelity of physically equivalent gates implemented on physical qubits. By running a randomized benchmarking protocol in the logical code space of the [4,2,2] code, we observe an order of magnitude improvement in the infidelity of the gates, with the two-qubit infidelity dropping from 5.8(2)% to 0.60(3)%. …

Papers that cite it

1. Close Not relevant

   Entangled logical qubits on a superconducting quantum processor

   Robin Harper, X. C. Kolesnikow, Campbell K. McLauchlan et al. · 2026 · Not summarized yet

   Abstract

   We demonstrate high-fidelity logical qubit operations using \texttt{ibm\_phoenix}, a square-lattice array of 120 coupled superconducting qubits that are capable of fast reset. Using strategies to exclude underperforming components together with noise informed decoding, we routinely produce surface codes at distance-3 and distance-5 with logical error per round below 1\%. We demonstrate entanglement between two logical qubits, where logical Bell-state fidelities above 93\% are observed for entanglement created via lattice surgery. With three logical qubits and lattice surgery, we perform logical teleportation of a range of states and gates, observing fidelities in the range 78\% - 93\%. Using…