摘要

The charge and spin degrees of freedom of an electron constitute natural bases for constructing quantum two level systems, or qubits, in semiconductor quantum dots. The quantum dot charge qubit offers a simple architecture and high-speed operation, but generally suffers from fast dephasing due to strong coupling of the environment to the electron’s charge. On the other hand, quantum dot spin qubits have demonstrated long coherence times, but their manipulation is often slower than desired for important future applications. This talk will review experimental progress of fast semiconductor based quantum qubits, including single dot spin qubits, charge qubits and recently developed ‘hybrid’ qubits formed by three electrons in Si/SiGe double quantum dots or GaAs. Starting from discussing general introduction to quantum transport measurements in quantum dots, circuit design, and material issues for developing highly coherent qubits, the talk will focus on discussing implementations of advanced quantum measurement and validation protocols, largely adopting techniques developed in superconducting qubits and nuclear magnetic resonance research fields.

报告人简介

Prof. Dohun Kim has recieved his Ph.D at Univ. of Maryland, USA in the field of quantum transport of topological insulators. During his postdoctoral study, he and coworkers at Univ. of Wisconsin invented a new type of semiconductor qubit: quantum dot hybrid qubit. Since then he has been actively working in the field of quantum coherent nano device transport in condensed matter physics and quantum coherent control for quantum information science since. He recently joined the faculty of physics department at Seoul National University in South Korea and is working as assistant professor from 2016. Dr. Kim's research area lies at the intersection of semiconductor physics, quantum computation, and nanodevice-based engineered quantum systems.