- 날짜: 2022년 1월 12일 (수) 15:00 ~ 17:00

- 주제: SCQC 정기 세미나

- 장소: Zoom 회의

- 초청연사 -

이경훈(UC Berkeley) 15:00~17:00 

"Visualizing  moiré superlattices in twisted bilayer graphene and extending coherence in superconducting qubits" 

  A moiré superlattice is produced by stacking lattice-mismatched 2D materials or by introducing misalignment. The moiré superlattice generates periodic potential that can strongly modify the electronic properties of the constituent 2D layers. However, the moiré superlattice may contain structural details such as atomic reconstruction into relaxed domains and local inhomogeneity. Thus, a high-resolution imaging probe is critical to correlate the moiré structure with the resulting material behavior. The first part of my talk, I will demonstrate the versatility of scanning impedance microwave microscopy (sMIM) in imaging the moiré in various graphitic systems at ambient conditions. In the second part of my talk, I will discuss superconducting circuits, one of the promising candidates in a race to build scalable and fault-tolerant quantum computers. However, the coherence of superconducting qubits still needs to be improved much for testing useful algorithms. One of the main sources of decoherence is the non-equilibrium quasiparticles (QPs), which can be viewed as broken Cooper pairs (CPs). Our effort toward mitigation of decoherence will be introduced. 

[1] K. Lee*, MIB Utama*, S Kahn*, et al., Science Advances 2020 (in press), ArXiv:2006.04000 (2020)
[2] MIB Utama*, RJ Koch*, K. Lee*, et al., Nature Physics 2020 (in press), ArXiv:1912.00587