KPS test conference

31 May 2021, 09:00 → 2 Jun 2021, 11:00 Asia/Seoul

101호 (대전컨벤션센터)

Sooa Park (The Korean Physical Society)

KPS test conference

Monday, 31 May

Session A: Applied Physics

1 What makes a good Quantum Computing Control System?

When building a quantum computer, the classical control system can make the difference between success and failure. In this workshop, we will present several case studies involving researchers at the forefront of quantum technology and discuss the criteria that we consider crucial for the design of control systems matching experimental requirements. For example, with the ever-increasing number and quality of available qubits, control electronics need to be more specialized and less costly. At the same time, features such as digital oscillators and pre-compensation must simplify the workflow while enabling better gate fidelities. We will also look into why system architecture and software adaptation are increasingly important.

Speaker: Mr Tobias Thiele (Zurich Instruments AG)

Session A: particle physics

Convener: Sooa Park (The Korean Physical Society)

2 Search for non-thermal Dark Matter in Monotop Events in Proton-Proton Collisions at 13 TeV

We study a minimal non-thermal dark matter (DM) model which can explain both the existence of dark matter and baryon asymmetry in the universe. Two color-triplet scalars with O(TeV) mass and a singlet Majorana fermion are required in this study. A new fermion with mass of O(GeV) becomes stable and can play the role of a DM candidate when it is approximately the same mass as proton. In this model, the DM candidate interacts with top quark via the exchange of the colored scalar fields. We search for this non-thermal dark matter candidate using monotop events.

Speaker: JKPS KPS (KPS)

Session B: Nuclear Physics

Convener: Sooa Park (The Korean Physical Society)

3 Mesoscale properties of mutualistic networks in ecosystems

Uncovering structural properties of ecological networks is a crucial starting point of studying the system's stability in response to various types of perturbations. We analyze pollination and seed disposal networks, which are representative examples of mutualistic networks in ecosystems, in various scales. In particular, we examine mesoscale properties such as the nested structure, the core-periphery structure, and the community structure by statistically investigating their interrelationships with real network data. As a result of community detection in different scales, we find the absence of meaningful hierarchy between networks, and the negative correlation between the modularity and the two other structures (nestedness and core-periphery-ness), which themselves are highly positively correlated. In addition, no characteristic scale of communities is perceivable from the community-inconsistency analysis. Therefore, the community structures, which are most widely studied mesoscale structures of networks, are not in fact adequate to characterize the mutualistic networks of this scale in ecosystems.

Speaker: SOOJUNG LEE (KPS)

4 Dependence on annealing temperature of lifetimes in zircon

Time-resolved optically stimulated luminescence (TR-OSL) sensitivity and lifetimes on the various thermal treatment for natural zircon from Brazil were investigated. Analyses of the TR-OSL spectra have showed that the decay is composed of two exponential components with lifetimes depending on the sample treatments. This change of the lifetimes is discussed in terms of a model previously used to explain thermal sensitization. The luminescence lifetime data are best explained by the presence of two luminescence centers, depending on the thermal history.

Speaker: Prof. Duk Geun HONG (Kangwon National University)

Tuesday, 1 June

Session C: Condensed Matter Physics

Convener: Sooa Park (The Korean Physical Society)

5 Search for flavor-changing neutral current interaction of the top quark and the Higgs boson decaying into bb bar at sqrt[s] = 13 TeV with CMS Run2 data

We present the results of searching for flavor-changing neutral current (FCNC) in the interaction of top quark and Higgs boson are presented. Large Hadron Collider (LHC) has accumulated proton-proton collision data corresponding to an integrated luminosity of 140 fb-1 at a center-of-mass energy of 13 TeV with the CMS detector during Run2. Using these datasets, the search is performed with the events of the final state of one isolated lepton, at least three jets including more than two b jets. Multivariate analysis techniques are utilized in various stages of analysis to improve the sensitivity of signal events. As no significant deviation is observed from the predicted background, we set upper limits on cross section and branching fraction of FCNC interaction in tHq coupling.

Speaker: Mr Jiwon Park (Hanyang University)

12:00 Lunch Break

Lunch Break

Poster Session: poster

Poster Session

Convener: Sooa Park (The Korean Physical Society)

6 Excitons in twisted MoSe2/MoSe2 bilayers: the effect of broken mirror symmetry

Van der Waals heterostructures made by stacking dissimilar materials or by introducing a twist angle
between layers can exhibit many exotic properties that are not present from their bulk counterparts.
Indeed, recent experiments on transition metal dichalcogenide (TMD) bilayers suggest that this
structural engineering can lead to periodic confinement of excitons and exciton hybridization. These
systems, a solid-state analogue of an optical lattice for ultracold atoms and molecules, are therefore a
particularly promising platform for a multitude of applications, such as the creation of quantum dot
arrays and the realization of excitonic topological insulators. However, in order to harness their full
potential, it is critical to first understand how the local exciton properties are modified by the crystal
structure. To date, such studies have remained a significant challenge due to the small size in
reconstructed domains in typical heterostructures (on the order of 1-10 nanometers and thus much
smaller than the optical diffraction limit).
In the present work, we overcome this limitation and explore the impacts of the local crystal structure
on TMD excitons by fabricating near zero twist angle MoSe2/MoSe2 bilayers. This enables us to create
large, twinned rhombohedral AB and BA domains with broken mirror and inversion symmetry. By
performing far-field, spatially resolved, spectroscopic measurements of the individual domains, we
demonstrate that both momentum-indirect interlayer excitons (XI,1) and momentum-direct interlayer
excitons (XI,2) have domain-specific dipole orientations that are perpendicular to the basal plane.
Furthermore, we show that it is possible to electrostatically control both the preferred dipole
orientation of XI,1 and hybridization between XI,2 and the intralayer excitons (X0). Importantly, we
support our experimental observations with first-principle density functional theory calculations, which
are in quantitative agreement. Our results shed light on the effect of crystal symmetry on TMD optical
properties and form the foundation for engineering exciton properties via domain engineering in van
der Waals heterostructures. Therefore, they open up new avenues for designing periodic domain
structures to explore quantum emitter arrays, topological exciton insulators and strongly correlated
exciton lattices for Hubbard model physics.

Speakers: InJi Song (KPS) , Namsoo Kim (UOS)

7 Proton decay of 23Mg

The 31-MeV proton beams have been delivered from the Holifield Radioactive Ion Beam Facility (HRIBF) at Oak Ridge National Laboratory (ORNL). Excited states in 23Mg were populated through the 24Mg(p,d)23Mg nucleon transfer reactions. By analyzing recoiling deuteron spectra, the excited states of 23Mg could be identified. By requiring coincidences between the reaction deuterons and the decay protons, proton decays of the excited 23Mg were studied. This research covers the energy levels of 23Mg ranging from 8.044 to 9.642 MeV decaying to several 22Na levels up to the 7th excited state, which is a wide range compared to the previous research. Branching ratios of all the transitions were obtained. The technique employed in this study is found to be a useful analysis in addition to a transfer reaction study.

Speaker: gildong Hong (JKPS)