BOOTH Robert

PhD graduated
Team : QI
Departure date : 02/28/2022

Supervision : Damian MARKHAM

Co-supervision : PERDRIX Simon

Measurement-based quantum computation beyond qubits

Measurement-based quantum computation (MBQC) is an alternative model for quantum computation, which makes careful use of the properties of the measurement of entangled quantum systems to perform transformations on an input. It differs fundamentally from the standard quantum circuit model in that measurement-based computations are naturally irreversible. This is an unavoidable consequence of the quantum description of measurements, but begets an obvious question: when does an MBQC implement an effectively reversible computation? The measurement calculus is a framework for reasoning about MBQC with the remarkable feature that every computation can be related in a canonical way to a graph. This allows one to use graph-theoretical tools to reason about MBQC problems, such as the reversibility question, and the resulting study of MBQC has had a large range of applications.
However, the vast majority of the work on MBQC has focused on architectures using the simplest possible quantum system: the qubit. It remains an open question how much of this work can be lifted to other quantum systems. In this thesis, we begin to tackle this question, by introducing analogs of the measurement calculus for higher- and infinite-dimensional quantum systems. More specifically, we consider the case of qubits when the local dimension is an odd prime, and of continuous-variable systems familiar from the quantum physics of free particles. In each case, a calculus is introduced and given a suitable interpretation in terms of quantum operations. We then relate the resulting models to the standard circuit models, using graph-theoretical tools called ``flow'' conditions.

Defence : 02/22/2022

Jury members :

Dan Browne, Professor at University College London [rapporteur]
Robert Raussendorf, Professor at University of British Columbia [rapporteur]
Ross Duncan, Fellow at University of Strathclyde
Claudia Faggian, Chargée de Recherche CNRS à l'IRIF
Elham Kashefi, Directrice de Recherche CRNS au LIP6
Simon Perdrix, Directeur de Recherche Inria au LORIA Nancy
Damian Markham, Charge de Recherche CNRS au LIP6

Departure date : 02/28/2022

2022-2023 Publications