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.

Establishing a reliable method to form scalable neutral-atom platforms is an essential cornerstone for quantum computation, quantum simulation and quantum many-body physics. Here we demonstrate a real-time transport of single atoms using holographic microtraps controlled by a liquid-crystal spatial light modulator. For this, an analytical design approach to flicker-free microtrap movement is devised and cold rubidium atoms are simultaneously rearranged with 2N motional degrees of freedom, repres

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

Finding the maximum independent set (MIS) of a large-size graph is a nondeterministic polynomial-time (NP)-complete problem not efficiently solvable with classical computations. Here, we present a set of quantum adiabatic computing data of Rydberg-atom experiments performed to solve the MIS problem of up to 141 atoms randomly arranged on the king lattice. A total of 582,916 events of Rydberg-atom measurements are collected for experimental MIS solutions of 733,853 different graphs. We provide th

Abstract There is a growing interest in harnessing the potential of the Rydberg‐atom system to address complex combinatorial optimization challenges. Here an experimental demonstration of how the quadratic unconstrained binary optimization (QUBO) problem can be effectively addressed using Rydberg‐atom graphs is presented. The Rydberg‐atom graphs are configurations of neutral atoms organized into mathematical graphs, facilitated by programmable optical tweezers, and designed to exhibit many‐body

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