Optimal programming of quantum gates

Abstract

A universal quantum processor is a device that can approximately implement any desired quantum gate on a given system. The specification of the desired gate is provided by a program, which in most implementations of quantum computing consists of classical data. From the foundational point of view, however, it is interesting to explore the more general scenario where the program is itself a quantum system. In the past two decades, a major open question has been to determine how the size of the smallest quantum program scales with the required accuracy in the implementation of the desired gate. Here we answer the question, by proving a bound on the size of the program and designing a concrete protocol that attains the bound in the asymptotic limit. Our result is based on the representation theory of the special unitary group. It provides improved bounds on the estimation of unitary gates, and on the implementation of quantum protocols subject to conservation laws.

About
The purpose of the Team-Net Quantum Computing Colloquium series is to expose Polish and international researchers, as well as interested peers, to the most important recent achievements and trends in the field of quantum computing. Seminars will be taking place on a monthly basis, on Wednesdays at 16:00 CET. Topics of the colloquium include, but are not limited to:

• Near-term quantum algorithms
• Quantum supremacy experiments
• Resource-theoretic approaches to quantum computing
• Quantum machine learning
• Practical quantum error correction and error mitigation
• Mathematical aspects of quantum computing and many-body physics

Webpage of the project: nisq.pl