Seminars 2026

Superconducting qubit has become one of the major platform in realizing practical, utility-scale quantum computing. The qubit consists of Josephson junctions integrated in passive microwave circuits. As the technology develops and commercialization is advancing, the quantum eco-system requires a robust supply chain in that each player focuses on their own strength to provide the best performance components for quantum machines. By leveraging the semiconductor infrastructure of Korea, we have established a quantum-dedicated Fab., or the QFab [1], in SKKU. QFab is a quantum foundry that provides superconducting qubit device fabrication to quantum researchers. In SKKU QFab, we have 3- to 6-inch complete process of superconducting devices in general. As an example of transmon qubits, we tape out every quarter. The fab typically targets around 1.5% standard deviation uniformity on chip. Recently we successfully delivered 20-qubit quantum processors to the Korea Research Institute of Standards and Science (KRISS), with which in order them to build a full-stack 20-qubit quantum computing system as a national flagship project. In coming years, we plan to extend the fab capability for up to hundreds of qubits and 8-inch capability, in collaboration with the Korean national nanofabrication facilities (KANC). In this presentation, I will present our fabrication results and QFab performances, with example of devices. I will also introduce our SKKU research laboratory research activities that covers various superconducting device research, including Qubit, SNSPD, TWPA and full-stack quantum computing system integration up to algorithm applications.

[1] Qfab: www.qfab.kr

Indico (with zoom link) - slides -  video recording

This talk provides an introduction to the theoretical and physical foundations of quantum computing. We begin with an overview of computational complexity theory, exploring the key complexity classes — P, NP, BQP, and NP-complete — and explaining why quantum computers are expected to offer advantages over classical machines for certain problems. We discuss how quantum algorithms can provide exponential speedups and where problems like Hamiltonia simulation fit within this landscape.
In the second part, we turn to the physical implementation of quantum computers using superconducting qubits. We describe the transmon qubit, microwave resonator readout, and two-qubit gate operations. We then present Rigetti Computing's approach to scaling: chiplet-based architectures with tunable couplers, 3D signal delivery, and alternating bias assisted annealing (ABAA) for qubit frequency precision. We close with recent experimental results demonstrating 99.5% two-qubit gate fidelity on a 36-qubit chiplet processor and an outlook toward fault-tolerant quantum computing at scale.

Indico (with zoom link) - slides -  video recording