scholarly journals Fault-tolerant quantum error detection

2017 ◽  
Vol 3 (10) ◽  
pp. e1701074 ◽  
Author(s):  
Norbert M. Linke ◽  
Mauricio Gutierrez ◽  
Kevin A. Landsman ◽  
Caroline Figgatt ◽  
Shantanu Debnath ◽  
...  
Keyword(s):  
Error Detection ◽  
Fault Tolerant ◽  
Quantum Error

scholarly journals Exponential suppression of bit or phase errors with cyclic error correction

Nature ◽  
2021 ◽  
Vol 595 (7867) ◽  
pp. 383-387
Author(s):  
◽  
Zijun Chen ◽  
Kevin J. Satzinger ◽  
Juan Atalaya ◽  
Alexander N. Korotkov ◽  
...  
Keyword(s):  
Error Correction ◽  
Error Detection ◽  
Fault Tolerant ◽  
Error Rates ◽  
Quantum Error Correction ◽  
Superconducting Qubits ◽  
Two Dimensional ◽  
Logical Error ◽  
Quantum Error ◽  
Logical Qubit

AbstractRealizing the potential of quantum computing requires sufficiently low logical error rates1. Many applications call for error rates as low as 10−15 (refs. 2–9), but state-of-the-art quantum platforms typically have physical error rates near 10−3 (refs. 10–14). Quantum error correction15–17 promises to bridge this divide by distributing quantum logical information across many physical qubits in such a way that errors can be detected and corrected. Errors on the encoded logical qubit state can be exponentially suppressed as the number of physical qubits grows, provided that the physical error rates are below a certain threshold and stable over the course of a computation. Here we implement one-dimensional repetition codes embedded in a two-dimensional grid of superconducting qubits that demonstrate exponential suppression of bit-flip or phase-flip errors, reducing logical error per round more than 100-fold when increasing the number of qubits from 5 to 21. Crucially, this error suppression is stable over 50 rounds of error correction. We also introduce a method for analysing error correlations with high precision, allowing us to characterize error locality while performing quantum error correction. Finally, we perform error detection with a small logical qubit using the 2D surface code on the same device18,19 and show that the results from both one- and two-dimensional codes agree with numerical simulations that use a simple depolarizing error model. These experimental demonstrations provide a foundation for building a scalable fault-tolerant quantum computer with superconducting qubits.

scholarly journals Fault-tolerant detection of a quantum error

Science ◽  
2018 ◽  
Vol 361 (6399) ◽  
pp. 266-270 ◽  
Author(s):  
S. Rosenblum ◽  
P. Reinhold ◽  
M. Mirrahimi ◽  
Liang Jiang ◽  
L. Frunzio ◽  
...  
Keyword(s):  
Error Detection ◽  
Fault Tolerant ◽  
Critical Component ◽  
Detection Scheme ◽  
Dephasing Time ◽  
Order Of Magnitude ◽  
Quantum Error ◽  
Specific Error ◽  
Logical Qubit

A critical component of any quantum error–correcting scheme is detection of errors by using an ancilla system. However, errors occurring in the ancilla can propagate onto the logical qubit, irreversibly corrupting the encoded information. We demonstrate a fault-tolerant error-detection scheme that suppresses spreading of ancilla errors by a factor of 5, while maintaining the assignment fidelity. The same method is used to prevent propagation of ancilla excitations, increasing the logical qubit dephasing time by an order of magnitude. Our approach is hardware-efficient, as it uses a single multilevel transmon ancilla and a cavity-encoded logical qubit, whose interaction is engineered in situ by using an off-resonant sideband drive. The results demonstrate that hardware-efficient approaches that exploit system-specific error models can yield advances toward fault-tolerant quantum computation.

scholarly journals Logical-qubit operations in an error-detecting surface code

2021 ◽  
Author(s):  
Jorge Marques ◽  
Boris Varbanov ◽  
Miguel Moreira ◽  
Hany Ali ◽  
Nandini Muthusubramanian ◽  
...  
Keyword(s):  
Error Detection ◽  
Fault Tolerant ◽  
The Road ◽  
Logical Operations ◽  
The Difference ◽  
Surface Code ◽  
On The Road ◽  
Qubit Operations ◽  
Quantum Error ◽  
Logical Qubit

Abstract Future fault-tolerant quantum computers will require storing and processing quantum data in logical qubits. We realize a suite of logical operations on a distance-two logical qubit stabilized using repeated error detection cycles. Logical operations include initialization into arbitrary states, measurement in the cardinal bases of the Bloch sphere, and a universal set of single-qubit gates. For each type of operation, we observe higher performance for fault-tolerant variants over non-fault-tolerant variants, and quantify the difference through detailed characterization. In particular, we demonstrate process tomography of logical gates, using the notion of a logical Pauli transfer matrix. This integration of high-fidelity logical operations with a scalable scheme for repeated stabilization is a milestone on the road to quantum error correction with higher-distance superconducting surface codes.

scholarly journals Quantum error detection .II. Bounds

2000 ◽  
Vol 46 (3) ◽  
pp. 789-800 ◽  
Author(s):  
A.E. Ashikhmin ◽  
A.M. Barg ◽  
E. Knill ◽  
S.N. Litsyn
Keyword(s):  
Error Detection ◽  
Quantum Error

scholarly journals Theory of quasi-exact fault-tolerant quantum computing and valence-bond-solid codes

2021 ◽  
Author(s):  
Dongsheng Wang ◽  
Yunjiang Wang ◽  
Ningping Cao ◽  
Bei Zeng ◽  
Raymond Lafflamme
Keyword(s):  
Error Correction ◽  
Quantum Computation ◽  
Fault Tolerant ◽  
Valence Bond ◽  
Quantum Error Correction ◽  
Quantum Codes ◽  
Error Correction Codes ◽  
Exact Quantum ◽  
Valence Bond Solid ◽  
Quantum Error

Abstract In this work, we develop the theory of quasi-exact fault-tolerant quantum (QEQ) computation, which uses qubits encoded into quasi-exact quantum error-correction codes (``quasi codes''). By definition, a quasi code is a parametric approximate code that can become exact by tuning its parameters. The model of QEQ computation lies in between the two well-known ones: the usual noisy quantum computation without error correction and the usual fault-tolerant quantum computation, but closer to the later. Many notions of exact quantum codes need to be adjusted for the quasi setting. Here we develop quasi error-correction theory using quantum instrument, the notions of quasi universality, quasi code distances, and quasi thresholds, etc. We find a wide class of quasi codes which are called valence-bond-solid codes, and we use them as concrete examples to demonstrate QEQ computation.

A Recovery-Oriented Approach for Software Fault Diagnosis in Complex Critical Systems

2012 ◽  
pp. 29-56
Author(s):  
Gabriella Carrozza ◽  
Roberto Natella
Keyword(s):  
Error Detection ◽  
Traffic Control ◽  
Fault Location ◽  
Fault Tolerant ◽  
Fault Injection ◽  
Critical Systems ◽  
Software Faults ◽  
Real World Application ◽  
Complex Fault ◽  
Detection Quality

This paper proposes an approach to software faults diagnosis in complex fault tolerant systems, encompassing the phases of error detection, fault location, and system recovery. Errors are detected in the first phase, exploiting the operating system support. Faults are identified during the location phase, through a machine learning based approach. Then, the best recovery action is triggered once the fault is located. Feedback actions are also used during the location phase to improve detection quality over time. A real world application from the Air Traffic Control field has been used as case study for evaluating the proposed approach. Experimental results, achieved by means of fault injection, show that the diagnosis engine is able to diagnose faults with high accuracy and at a low overhead.

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