Advanced Logic Applications - Quantum Computers

- Design of Si-based Qubit Systems using High Performance Computer -

High performance computers (HPCs) accelerate the feasibility of quantum information processing. Quantum computers, processing the logic information with a sequence of the quantum bit (qubit), have obtained keen attention due to their extremely good efficiency in solving large-scale problems. Silicon, a well-known semiconductor material, has been regarded as a great material candidate for quantum computers as its decoherence time is extremely large.

Using HPCs, KISTI works on modeling researches with two purposes: (1) pre-estimate Si-based multi-qubit systems to provide experimentalists with a guide-line of potential device designs, and (2) present theoretical evidences to validate physically realized device prototypes. While the experimental realization should become the central part of advanced device research, the experimental work itself is hard to be accepted as a good research outcome unless the result is validated in a theory perspective.

Since 2011, KISTI have started quantum device modeling research. Dr. Hoon Ryu, a senior researcher at KISTI, developed a parallel solver to compute the electronic structures of nanoscale devices in a 3D manner. Pursuing the research collaboration with Purdue University in United States and University of New South Wales in Australia, Dr. Ryu has led the modeling part of collaborative researches.

The team produces quite fruitful and world-leading research outcomes. In 2012, the study of the metallic property of “ultrathin P-doped Si nanowires”, which could be used as inter-connectors for Si qubit systems, was published in <Science>. In the same year, the team demonstrated the feasibility of a single P-doped Si qubit system, publishing the result in <Nature Nanotechnology>. In 2013, the design guideline for ultra-thin Si-P nanowires are published in <RSC Nanoscale> (IF 6.2). In 2014, the multi-qubit systems have been demonstrated for the first time using Si-P, and the result was again published in <Nature Nanotechnology>.

Dr. Ryu said that “We have so far succeeded in getting 2~3 P atoms integrated in Si bulk. To expand the scalability of Si-based multi-qubit systems, much more P atoms need to be successfully integrated, guaranteeing reasonably good device performances. We are moving to the next step for integration of 4~8 P atoms, and HPC-based modeling research of course will play a key role because it not only accelerates the experimental work by estimating performances in advance, but also presents a comprehensive theoretical framework of Si-P electronics that could be extremely useful for the potential device design."

Dr. Hoon Ryu

1. Current Affiliation

Senior Researcher in Supercomputing R/D Center,

National Institute of Supercomputing and Networking,

Korea Institute of Science and Technology Information.

2. Education

○ B.S. in Electrical Engineering, Seoul National University, Republic of Korea

○ M.S. in Electrical Engineering, Stanford University, USA.

○ Ph.D. in Electrical Engineering, Purdue University, USA.