이장우 교수

Based on phase-space structures of quantum states, we propose a novel measure to quantify macroscopic quantum superpositions. Our measure simultaneously quantifies two different kinds of essential information for a given quantum state in a harmonious manner: the degree of quantum coherence and the effective size of the physical system that involves the superposition. It enjoys remarkably good analytical and algebraic properties. It turns out to be the most general and inclusive measure ever prop

We report the synthesis of glycine on interstellar ice-analog films composed of water, methylamine (MA), and carbon dioxide under irradiation of ultraviolet (UV) photons. Analysis of the UV-irradiated ice films by in situ mass spectrometric methods revealed glycine and other isomers as photochemical products. Deuterium-labeling experiments were conducted to determine the structures of the photoproducts and to examine their formation pathways. The reactions occur via photocleavages of C–H and N–H

We have examined the elementary molecular processes responsible for proton transfer and HD exchange in thin ice films for the temperature range of 100-140 K. The ice films are made to have a structure of a bottom D(2)O layer and an upper H(2)O layer, with excess protons generated from HCl ionization trapped at the D(2)OH(2)O interface. The transport behavior of excess protons from the interfacial layer to the ice film surface and the progress of the HD exchange reaction in water molecules are ex

We propose an optical scheme to generate a superposition of coherent states with enhanced size adopting an interferometric setting at the single-photon level currently available in the laboratory. Our scheme employs a nondegenerate optical parametric amplifier together with two beam splitters so that the detection of single photons at the output conditionally implements the desired superposition of second-order photonic operations. We analyze our proposed scheme by considering realistic on-off p

We establish bounds for the domination number of a digraph in terms of the minimum indegree and the order, and then we find a sharp upper bound for the domination number of a weak digraph with minimum indegree one. We also determine the domination number of a random digraph.

We investigate the violation of Leggett's inequality for nonlocal realism using entangled coherent states and various types of local measurements. We prove mathematically the relation between the violation of the Clauser-Horne-Shimony-Holt form of Bell's inequality and Leggett's one when tested by the same resources. For Leggett inequalities, we generalize the nonlocal realistic bound to systems in Hilbert spaces larger than bidimensional ones and introduce an optimization technique that allows

We analyze effects of squeezing upon superpositions of coherent states (SCSs) and entangled coherent states for Bell-inequality tests. We find that external squeezing can always increase the degrees of Bell violations, if the squeezing direction is properly chosen, for the case of photon parity measurements. On the other hand, when photon on/off measurements are used, the squeezing operation can enhance the degree of Bell violations only for moderate values of amplitudes and squeezing. We point

In this paper, a new learning method to quantify data uncertainty without suffering from performance degradation in Single Image Super Resolution (SISR) is proposed. Our work is motivated by the fact that the idea of loss design for capturing uncertainty and that for solving SISR are contradictory. As to capturing data uncertainty, we often model the output of a network as a Euclidian distance divided by a predictive variance, negative log-likelihood (NLL) for the Gaussian distribution, so that

We present a quantum theory of the amplification of light undergoing a total internal reflection. We show that the light amplification is due to the stimulated emission of evanescent-mode photon from the active region of the interface. Our theoretical results are in good agreement with experimental observations and provide deeper understanding of the quantum-mechanical characteristics of the evanescent wave. A corresponding triplet-mode laser theory is also presented.

Among many detrimental injuries, alcohol is implicated in hepatitis, fatty liver, hepatic fibrosis, and cirrhosis. The purpose of this study was to evaluate the protective effect of bio-active ceramic water on alcohol-induced hepatic injury in pigs. Twelve male Landrace pigs were divided into 3 groups. Groups 1, 2, and 3 were fed with bio-active ceramic water + normal liquid diet, bio-active ceramic water + liquid diet containing 15% ethanol, and tap water + liquid diet containing 15% ethanol fo

We find bounds for the domination number of a tour- nament and investigate the sharpness of these bounds. We also find the domination number of a random tournament.

본 논문에서는 인덕티브 커플링 송수신 회로를 위한 효과 적인 신호 전달 기법을 제안하기 위하여 인덕티브 커플링 채널과기존의 신호 전달 기법들을 분석 하였다. 신호 전달 기법을 공정히 비교하기 위하여 새로운 성능 비교 지수를 소개하고 이를토대로 비교 결과를 산출할 시 NRZ 신호 전달 기법이 기존에 제안 되었던 BPM 신호 전달 기법보다 더 우수함을 나타내었다. 모의실험은 CMOS 0.13μm 공정을 이용하여 송수신 회로를 설계하였으며 인덕터는 칩 내 spiral 인덕터를 가정하여 모델링 하였다.

The effect of the adsorbate mass on an Eley-Rideal (ER) reaction is examined for the reactive ion scattering (RIS) of Cs+ from physisorbed adsorbates (Ar, Kr, Xe and N2) on a Ru(0001) surface at hyperthermal energy (10-60 eV). The measurement of the RIS cross-section, or the efficiency for ER-type abstraction of surface adsorbates, reveals an inverse proportionality between the square root of the cross-section and the mass of the noble gases. This relationship is explained by the inertia effect