안재욱 교수

Information was stored as quantum phase in an N-state Rydberg atom data register. One or more flipped states stored in an eight-state atomic wave packet could be retrieved in a single operation, in agreement with a recent proposal by Grover.

We demonstrate the use of optical pulse-shaping technique in conjunction with difference frequency generation in a non-linear optoelectronic crystal for generating synthesized waveforms at terahertz frequencies. Spectral phase modulations, programmed using Gerchberg-Saxton algorithm and prepared in a spatial light Fourier filter, produce tailored terahertz pulses, including chirped pulses, zero-area pulses, and trains of multiple pulses for tunable narrow-band terahertz radiation up to 2.0 THz.

A terahertz half-cycle pulse was used to retrieve information stored as quantum phase in an N-state Rydberg atom data register. The register was prepared as a wave packet with one state phase reversed from the others (the "marked bit"). A half-cycle pulse then drove a significant portion of the electron probability into the flipped state via multimode interference.

All-optical gain clamping scheme of erbium-doped fiber amplifier (EDFA) based on partial reflection of amplified spontaneous emission (ASE) into the EDFA is proposed and successfully demonstrated by using a coarse wavelength division multiplexing coupler with a mirror as an ASE reflector. The proposed gain-clamped EDFA (GC-EDFA) has good gain clamping characteristics up to -12 dBm of input signal power with 1-dB gain reduction from a clamped gain of 21 dB. Thanks to noncavity structure of the pr

We analyze a quantum search protocol to retrieve phase information from a Rydberg-atom data register using a subpicosecond half-cycle electric field pulse. Calculations show that the half-cycle pulse can perform the phase retrieval only within a range of peak field values. By varying the phases of the constituent orbitals of the Rydberg wave packet register, we demonstrate coherent control of the phase retrieval process. By specially programming the phases of the orbitals comprising the initial

An all-polymer wavelength channel selector is proposed and fabricated using chip-to-chip bonding of 16-channel electrooptic polymer switch array between two polymer arrayed waveguide gratings for the first time to our knowledge. A low power penalty of 0.1 dB at 10 Gb/s shows its potential as a wavelength channel selector for a packet switching system. Further efforts, however, should be paid to improve upon the large insertion loss of about 28 dB and bias phase drift problem for the proposed pol

In contrast to classical chemical reaction kinetics, for diffusion limited chemical reactions the anisotropy of the geometry has far reaching effects. We use tubular two and three-dimensional spaces to illustrate and discuss the dimensional crossover in A+B→0 reactions due to dimensional compactification. We find that the crossover time tc=Wα scales as α=β/(a−b), where a, b, and β are given by the earlier and the late time inverse density scaling of ρ−1∼ta and ρ−1∼tbWβ, respectively. We also obt

Rydberg atom arrays offer flexible geometries of strongly interacting neutral atoms, which are useful for many quantum applications such as quantum simulation and quantum computation. Here, we consider an all-optical gate-based quantum computing scheme for the Rydberg atom arrays, in which auxiliary atoms (wire atoms) are used as a mean of quantum-mechanical remote-couplings among data-qubit atoms, and optical individual-atom addressing of the data and wire atoms is used to construct universal q

Summary form only given. Efforts paid to various pump schemes such as forward, backward and bidirectional pumping have made significant contributions to highly reliable erbium-doped fiber amplifiers (EDFAs) with high gain and low noise figure characteristics. Reflective type EDFAs by using a mirror and an optical isolator were proposed to achieve a better utilization of wasted pump energy. Therefore, this double-path EDFA doubled the gain coefficient compared to that of single-path ones. However

This paper deals with a parabolic-elliptic chemotaxis-consumption system with tensor-valued sensitivity $S(x,n,c)$ under no-flux boundary conditions for $n$ and Robin-type boundary conditions for $c$. The global existence of bounded classical solutions is established in dimension two under general assumptions on tensor-valued sensitivity $S$. One of main steps is to show that $\nabla c(\cdot,t)$ becomes tiny in $L^{2}(B_{r}(x)\cap Ω)$ for every $x\in\overlineΩ$ and $t$ when $r$ is sufficiently s

Terahertz polarization shaping technique is developed. We have used the combination of wedge-type diffractive optical components in conjunction with a circular InAs pattern to produce various THz waves with temporally-evolving polarization states.

본 연구에서는 디지털화 확산으로 증가하는 컴퓨팅과 스토리지 인프라인 데이터센터의 에너지 소비 및 탄소 배출 증가에 대한 지속 가능한 대안을 모색하고자 한다. 데이터센터는 서버와 데이터 저장장치를 365일 24시간 운영하기 때문에 전력 소모가 크고, 컴퓨터 장비를 사용하는 환경에서는 안정적인 온도와 습도를 유지해야하기 때문에 냉각 시스템이 필수적이다. 이를 위해 전력 사용량을 줄이기 위한 다양한 방법들이 제안되었으나, 본 연구에서는 저차압, 고효율 특성을 지닌 고효율 IoT 필터 솔루션을 적용하여 기존 부직포 필터 대비 냉각부하를 줄여 에너지 소비를 최적화하고, 탄소 배출을 줄여 데이터센터의 전력 효율을 향상시켜 환경부하를 줄이는 것으로 확인되었다. 이러한 접근 방식은 데이터센터가 환경 및 에너지 절감 측면에서 지속 가능한 방향으로 발전하는데 기여한다.

Using individually shaped three pulses in 2D Fourier transform optical spectroscopy, we retrieve and coherently control the amplitude and phase of the two-photon transition between 5P1/2 and 5P3/2 levels in atomic Rubidium.

Summary form only given. We demonstrate the use ofan N-state Rydberg system to mimic an N-qubit quantum register, and apply this system to solve the database search problem proposed by Grover in a single unitary operation.