QSE Quantum Seminar - Gil-Ho Lee

Please join us for the QSE Center Quantum Seminar with Gil-Ho Lee from POSTECH, South Korea who will give the talk "Understanding and utilizing graphene-based Josephson junctions" on Monday July 21st from 12pm to 1:30pm 
Location: CM 1 104

Pizzas will be available between the seminars at 12:00. All PhDs, postdocs, students, and PIs are welcome to join us.

TITLE: "Understanding and utilizing graphene-based Josephson junctions"

ABSTRACT:
Recent experimental works on graphene Josephson junctions (GJJs) will be discussed to understand the Andreev bound states (ABS) that govern the device physics of proximity Josephson junctions. Here, we implemented superconducting tunneling spectroscopy to investigate: (i) steady Floquet-Andreev states upon microwave irradiation, (ii) gate-tunable ABSs in bilayer graphene Josephson junctions, and (iii) topological Andreev bands in three-terminal GJJs.
In the latter half, we focus on utilizing GJJs as sensitive detectors for microwave photons and potentially dark matter. By exploiting the minute electronic specific heat and thermal conductivity of graphene, we demonstrated a GJJ-based microwave bolometer with a fundamentally limited noise-equivalent power, corresponding to the energy resolution of a single 32-gigahertz photon. We will introduce our effort for (i) optimizing GJJ parameters for better detection performance, (ii) improving superconducting contacts to graphene, and (iii) calibrating the detection performance for single photons across a wide spectrum.

BIO:
Gil-Ho Lee received a Ph.D. in physics from the Pohang University of Science and Technology (POSTECH) in South Korea in 2014. He was a postdoctoral researcher at Harvard University from 2014 to 2017. In 2017, he joined the Department of Physics at POSTECH, where he is currently an associate professor. His research interest includes quantum transport and macroscopic quantum phenomena of a superconductor/graphene hybrid nano-device, topological superconductivity of superconductor/topological material hybrid structures, non-equilibrium quantum physics in nano-devices, ultrabroad-bandwidth single-photon detection technology based on graphene Josephson junction, relativistic electronic optics phenomena in high-quality graphene, and Floquet quantum states in nano-devices.