Year: 2008
Type: dissertation
Abstract: Finding correctable encoding that protects against a quantum process is in general a difficult task. Two main obstacles are that an exponential number of experiments are needed to gain complete information about the quantum process, and known algorithmic methods for finding correctable encodings involve operations on exponentially large matrices. \n \nIn this thesis we discuss how useful partial information of a quantum channel can be systematically extracted by averaging the channel under the action of a set of unitaries in a process known as twirling. We show that in some cases it is possible to find correctable encodings for the channel using the partial information obtained via twirling. \n \nWe investigate the particular case of twirling over the set of Pauli operators and qubit permutations, and show that the resulting quantum operation can be characterized experimentally in a scalable \nmanner. A post-processing scheme for finding \nunitarily correctable codes for these twirled channels is presented which does \nnot involve exponentially large matrices. A test for non-Markovian noise using such a twirling process is also discussed.
Source: UWSpace (University of Waterloo)
Author: Easwar Magesan
Language: English
Subfield: Artificial Intelligence
Field: Computer Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2261994249