A walk through quantum noise: a study of error signatures and characterization methods
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Date
2019-09-17
Authors
Carignan-Dugas, Arnaud
Journal Title
Journal ISSN
Volume Title
Publisher
University of Waterloo
Abstract
The construction of large scale quantum computing devices might be one of the most exciting
and promising endeavors of the 21st century, but it also comes with many challenges.
As quantum computers are supplemented with more registers, their error profile generally
grows in complexity, rendering the enterprise of quantifying the reliability of quantum computations
increasingly difficult through naive characterization techniques. In the last decade,
a lot of efforts has been directed toward developing highly scalable benchmarking schemes.
A leading family of characterization methods built upon scalable principles is known as randomized
benchmarking (RB).
In this thesis, many tools are presented with the objective of improving the scalability,
and versatility of RB techniques, as well as demonstrating their reliability under various
error models.
The first part of this work investigates the connection between the error of individual
circuit components and the error of their composition. Before reasoning about intricate circuit
constructions, it is shown that there exists a well-motivated way to define decoherent
quantum channels, and that every channel can be factorized into a unitary-decoherent composition.
This dichotomy carries to the circuit evolution of important error parameters by
assuming realistic error scenarios. Those results are used to improve the confidence interval
of RB diagnoses and to reconcile experimentally estimated parameters with physically and
operationally meaningful quantities.
In the second part of this thesis, various RB schemes are either developed or more rigorously
analyzed. A first result consists of the introduction of “dihedral benchmarking”, a
technique which, if performed in conjunction with standard RB protocols, enables the characterization
of operations that form a universal gate-set. Finally, rigorous analysis tools are
provided to demonstrate the reliability of a highly scalable family of generator-based RB
protocols known as direct RB.
Description
Keywords
quantum information, quantum characterization, quantum computing, system characterization, randomized benchmarking