Logic error

Abstract: A system and method for error handling and recovery in a content distribution system is described in which errors corresponding to failed file operations (e.g., file transfer errors, file delete errors) are placed in an error queue. Error analysis logic reads the errors from the error queue and makes a determination as to whether the file operation errors are recoverable errors based on an error recovery policy. If the error analysis logic determines that recovery is possible, then one or more error recovery procedures are invoked. The procedures may be specific to the content delivery system (e.g., “Server X was down on 1/20 between 10:20 and 11:00 AM”), or may be more general (e.g., “attempt file transfers 5 times before quitting”). If it is determined that an error is not automatically recoverable, then the error is included in an error report.

Abstract: Surface codes are building blocks of quantum computing platforms based on 2D arrays of qubits responsible for detecting and correcting errors. The error suppression achieved by the surface code is usually estimated by simulating toy noise models describing random Pauli errors. However, Pauli noise models fail to capture coherent processes such as systematic unitary errors caused by imperfect control pulses. Here we report the first large-scale simulation of quantum error correction protocols based on the surface code in the presence of coherent noise. We observe that the standard Pauli approximation provides an accurate estimate of the error threshold but underestimates the logical error rate in the sub-threshold regime. We find that for large code size the logical-level noise is well approximated by random Pauli errors even though the physical-level noise is coherent. Our work demonstrates that coherent effects do not significantly change the error correcting threshold of surface codes. This gives more confidence in the viability of the fault-tolerance architecture pursued by several experimental groups. Coherent effects are shown not to play a significant role in error correction with quantum surface codes. To build a quantum computer, the quantum bit (qubit) has to be protected from external noise and steps have to be taken to detect and correct for errors. Surface codes are a type of quantum code that can correct for such errors. However, the models used to study such codes often fail to capture quantum coherent processes, which could play an important role. By performing large-scale simulations, Robert Konig from Technical University of Munich and an international team of collaborators show that coherent effects do not significantly impact the error correction in surface codes, giving confidence in the viability of this approach for developing fault-tolerance quantum computing architectures.

Abstract: Error taxonomies are useful because different types of errors have different commission and detection rates and because error mitigation techniques often are only useful for some types of errors. In the early 1990s, Panko and Halverson developed a spreadsheet error taxonomy. This paper updates that taxonomy to reflect human error research more fully. The taxonomy focuses on quantitative errors during development and testing but notes that qualitative errors are very important and that errors occur in all stages of the system development life cycle.

Abstract: This paper analyses the problem of systems' on-line testing with respect to logic errors due to crosstalk, delay and transient faults. In particular we show that logic errors due to crosstalk noise between internal, adjacent lines may not be on-line detectable by conventional concurrent error detection techniques using error detecting codes. Hence, a detector is proposed that allows the on-line detection of such logic errors, and that is self-checking with respect to a wide set of possible internal faults representative of realistic failures, including crosstalk, delay, and transient faults.