Towards practical classical processing for the surface code: Timing analysis

Fowler, Austin G.; Whiteside, Adam C.; Hollenberg, Lloyd C. L.

doi:10.1103/physreva.86.042313

Cited by 46 publications

(45 citation statements)

References 21 publications

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“…For example, detected errors could be corrected by solving a local optimization problem, whereby the values of a small cluster of encoded qubits that were flagged as erroneous and their neighbours are used to find the lowest energy solution possible. Other decoding schemes could be devised as needed, drawing, for example, on recent developments in optimal decoding of surface codes 50 . Another important venue for future studies is the development of more efficient QACcompatible codes capable of handling larger weight errors.…”

Section: Discussionmentioning

confidence: 99%

Error-corrected quantum annealing with hundreds of qubits

2014

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Quantum information processing offers dramatic speedups, yet is susceptible to decoherence, whereby quantum superpositions decay into mutually exclusive classical alternatives, thus robbing quantum computers of their power. This makes the development of quantum error correction an essential aspect of quantum computing. So far, little is known about protection against decoherence for quantum annealing, a computational paradigm aiming to exploit ground-state quantum dynamics to solve optimization problems more rapidly than is possible classically. Here we develop error correction for quantum annealing and experimentally demonstrate it using antiferromagnetic chains with up to 344 superconducting flux qubits in processors that have recently been shown to physically implement programmable quantum annealing. We demonstrate a substantial improvement over the performance of the processors in the absence of error correction. These results pave the way towards large-scale noise-protected adiabatic quantum optimization devices, although a threshold theorem such as has been established in the circuit model of quantum computing remains elusive.

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Section: Discussionmentioning

confidence: 99%

Error-corrected quantum annealing with hundreds of qubits

2014

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“…2. Extracting and processing the error syndrome must be executed on time scales of the same [96,123] examined this problem, finding that the processing requirements for surface-code error correction are not trivial; performing these calculations ''live'' where the results may be needed within e.g., 10 s could be one of the more important problems for engineering a quantum computer. Still, the recent progress in this area suggests that some combination of improved algorithm software and custom hardware can achieve the necessary performance [123].…”

Section: Timing Considerationsmentioning

confidence: 99%

Layered Architecture for Quantum Computing

et al. 2012

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We develop a layered quantum-computer architecture, which is a systematic framework for tackling the individual challenges of developing a quantum computer while constructing a cohesive device design. We discuss many of the prominent techniques for implementing circuit-model quantum computing and introduce several new methods, with an emphasis on employing surface-code quantum error correction. In doing so, we propose a new quantum-computer architecture based on optical control of quantum dots. The time scales of physical-hardware operations and logical, error-corrected quantum gates differ by several orders of magnitude. By dividing functionality into layers, we can design and analyze subsystems independently, demonstrating the value of our layered architectural approach. Using this concrete hardware platform, we provide resource analysis for executing fault-tolerant quantum algorithms for integer factoring and quantum simulation, finding that the quantum-dot architecture we study could solve such problems on the time scale of days.

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“…Figure 3(b) shows a possible sequence of measurement values and the associated inferred pattern of detection events. Given dots, lines, and detection events, the minimum weight perfect matching algorithm [38][39][40][41] can be used to find a set of paths of lines that connects all detection events in pairs or individually with a boundary such that the total weight of all lines in the set is minimal. This corresponds to a high probability pattern of errors leading to the observed detection events.…”

Section: The Repetition Codementioning

confidence: 99%

Coping with qubit leakage in topological codes

Fowler

2013

Phys. Rev. A

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122

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Many physical systems considered promising qubit candidates are not, in fact, two-level systems. Such systems can leak out of the preferred computational states, leading to errors on any qubits that interact with leaked qubits. Without specific methods of dealing with leakage, long-lived leakage can lead to time-correlated errors. We study the impact of such time-correlated errors on topological quantum error correction codes, which are considered highly practical codes, using the repetition code as a representative case study. We show that, under physically reasonable assumptions, a threshold error rate still exists, however performance is significantly degraded. We then describe simple additional quantum circuitry that, when included in the error detection cycle, restores performance to acceptable levels.Comment: 5 pages, 8 figures, comments welcom

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Towards practical classical processing for the surface code: Timing analysis

Cited by 46 publications

References 21 publications

Error-corrected quantum annealing with hundreds of qubits

Error-corrected quantum annealing with hundreds of qubits

Layered Architecture for Quantum Computing

Coping with qubit leakage in topological codes

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