Ancilla-driven quantum computation for qudits and continuous variables

Proctor, Timothy; Giulian, Melissa; Korolkova, Natalia; Andersson, Erika; Kendon, Viv

Abstract

Although qubits are the leading candidate for the basic elements in a quantum computer, there are also a range of reasons to consider using higher-dimensional qudits or quantum continuous variables (QCVs). In this paper, we use a general “quantum variable” formalism to propose a method of quantum computation in which ancillas are used to mediate gates on a well-isolated “quantum memory” register and which may be applied to the setting of qubits, qudits (for d > 2), or QCVs. More specifically, we present a model in which universal quantum computation may be implemented on a register using only repeated applications of a single fixed two-body ancilla-register interaction gate, ancillas prepared in a single state, and local measurements of these ancillas. In order to maintain determinism in the computation, adaptive measurements via a classical feed forward of measurement outcomes are used, with the method similar to that in measurement-based quantum computation (MBQC). We show that our model has the same hybrid quantum-classical processing advantages as MBQC, including the power to implement any Clifford circuit in essentially one layer of quantum computation. In some physical settings, high-quality measurements of the ancillas may be highly challenging or not possible, and hence we also present a globally unitary model which replaces the need for measurements of the ancillas with the requirement for ancillas to be prepared in states from a fixed orthonormal basis. Finally, we discuss settings in which these models may be of practical interest.

Citation

Proctor, T., Giulian, M., Korolkova, N., Andersson, E., & Kendon, V. (2017). Ancilla-driven quantum computation for qudits and continuous variables. Physical Review A, 95(5), Article 052317. https://doi.org/10.1103/physreva.95.052317

• Journal Article Type: Article
• Acceptance Date: Feb 27, 2017
• Online Publication Date: May 10, 2017
• Publication Date: May 10, 2017
• Deposit Date: Aug 18, 2017
• Publicly Available Date: Aug 18, 2017
• Journal: Physical Review A
• Print ISSN: 2469-9926
• Electronic ISSN: 2469-9934
• Publisher: American Physical Society
• Peer Reviewed: Peer Reviewed
• Volume: 95
• Issue: 5
• Article Number: 052317
• DOI: https://doi.org/10.1103/physreva.95.052317
• Public URL: https://durham-repository.worktribe.com/output/1378746
• Related Public URLs: https://arxiv.org/abs/1510.06462