Lee, Minchul

Minchul Lee is a Professor in Department of Applied Physics, Kyung Hee University. He obtained his Ph.D. in Department of Physics, Seoul National University. As theoretical condensed matter physicist, his research interests include quantum transport and phase transition in many-body quantum systems such as quantum-dot junctions, topological wires, and semi-condutor nanostructures. The recent studies are extended to the field of quantum entanglement, focusing on the dynamics and phase transition of quantum entanglement in open quantum systems.

Effect of spin-orbit interaction on the quantum transport in quantum-dot Josephson junctions in the Kondo regime

• Speaker: Minchul Lee (Kyung Hee University, Korea)
• Event: Quantum Technology Workshop 2026

In this talk we present the study on the effect of the spin-orbit interaction on the phase transitions and superconducting transport of quantum-dot Josephson junctions in the Kondo regime. We adopt the simplest model incorporating the spin-orbit interaction, in which the quantum dot has a single spinful level but an effective direct tunneling between two superconducting leads is opened, giving rise to nontrivial interference between two tunneling paths which can be modulated by the spin-orbit interaction. First, we found that the direct tunneling, if strong enough, can induce singlet-doublet phase transition which is opposite to one found in conventional quantum-dot Josephson junctions, producing a rich phase diagram: for example, there exists a phase where the junction is of spin doublet near $\phi=0$ and of spin singlet near $\phi=\pi$, where $\phi$ is the superconducting phase difference between two leads. Moreover, a finite spin-orbit interaction induces an effective Zeeman field whose magnitude is modulated by the superconducting phase $\phi$ as well and affects the phase transition and current in a nontrivial way, preferring the spin-polarized state. Finally, we propose a way to detect the role of spin-orbit interaction by examining the transport response with respect to the external magnetic field which induces a Zeeman field in the quantum dot.

Other Contributions

• Topological Insulators: Basics of Topological Insulators