Speaker

　　Title

　　Time

　　Venue

N202

　　Abstract

　　Topological quantum computation (TQC) is one of the most striking architectures that can realize fault-tolerant quantum computers. In TQC, the logical space and the quantum gates are topologically protected, i.e., robust against local disturbances. The topological protection, however, requires rather complicated lattice models and hard-to-manipulate dynamics; even the simplest system that can realize universal TQC--the Fibonacci anyon system--lacks a physical realization, let alone braiding the non-Abelian anyons. Here, we propose a disk model that can realize the Fibonacci-anyon system and construct the topologically protected logical spaces with the Fibonacci anyons. Via braiding the Fibonacci anyons, we can implement universal quantum gates on the logical space. Our disk model merely requires 2 physical qubits to realize 3 Fibonacci anyons at the boundary, and then by 15 sequential braiding operations to construct a topologically protected Hadamard gate, which is to date the least-resource requirement for TQC. To showcase, we implement a topological Hadamard gate with 2 nuclear spin qubits, which reaches 97.18% fidelity by randomized benchmarking. We further prove by experiment that the logical space and Hadamard gate are topologically protected: local disturbances due to thermal fluctuations result in a global phase only. As a platform-independent proposal, our work is a proof of principle of TQC and paves the way towards fault-tolerant quantum computation.

　　Affiliation

　　万义顿，复旦大学物理系长聘教授，华南理工大学计算机与经济学双学士(1998)、美国宾夕法尼亚大学计算机硕士(2002)、加拿大渥太华大学物理硕士(2004)，加拿大滑铁卢大学暨圆周理论物理研究所理论物理博士(2009)，于日本近畿大学 东京大学、加拿大圆周理论物理研究所做博士后，2016年加入复旦物理系，从事拓扑物态、量子信息与计算、量子引力等领域的交叉研究。