• Title/Summary/Keyword: Quantum communication

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Photoluminescence of ZnSe/CdSe/ZnSe Single Quantum Well (ZnSe/CdSe/ZnSe 단일양자우물의 광발광 특성)

  • Park, J.G.;O, Byung-Sung;Yu, Y.M.;Yoon, M.Y.;Kim, D.J.;Choi, Y.D.
    • Journal of the Korean Vacuum Society
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    • v.16 no.3
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    • pp.192-196
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    • 2007
  • ZnSe/CdSe/ZnSe single quantum wells with different well thickness were grown by hot wall epitaxy. The quantum well thicknesses were measured by TEM. The critical thickness of single quantum well layer was found to be about $9{\AA}$ from the intensities and the full-width at half maximum of photoluminescence(PL) spectra. When the thickness of quantum wells was less than the critical thickness, the Stoke's shift was confirmed from the comparison between PL and photoluminescence excitation spectra, and it may be due to the exciton binding energy. The PL peak energy dependence on the quantum well thickness was coincident with the theoretical values.

Platform for Manipulating Polarization Modes Realized with Jones Vectors in MATHEMATICA

  • Choi, Yong-Dae;Kim, Bogyeong;Yun, Hee-Joong
    • Journal of Astronomy and Space Sciences
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    • v.32 no.2
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    • pp.151-159
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    • 2015
  • The fundamental conception in physics of the propagation of the electromagnetic wave polarization in matter is newly understood as the cardinal keyword in free-space quantum communication technology and cosmology in astrophysics. Interactive visualization of the propagation mechanism of polarized electromagnetism in a medium with its helicity has accordingly received attention from scientists exploiting the protocol of quantum key distribution (QKD) to guarantee unconditional security in cryptography communication. We have provided a dynamic polarization platform for presenting the polarization modes of a transverse electromagnetic wave, converting the state of polarization through the arrangement of optical elements, using Jones vectors calculations in Methematica. The platform graphically simulates the mechanism of production and propagation of the polarized waves in a medium while satisfying Maxwell's equations.

A Study on the Information Reversibility of Quantum Logic Circuits (양자 논리회로의 정보 가역성에 대한 고찰)

  • Park, Dong-Young
    • The Journal of the Korea institute of electronic communication sciences
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    • v.12 no.1
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    • pp.189-194
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    • 2017
  • The reversibility of a quantum logic circuit can be realized when two reversible conditions of information reversible and energy reversible circuits are satisfied. In this paper, we have modeled the computation cycle required to recover the information reversibility from the multivalued quantum logic to the original state. For modeling, we used a function embedding method that uses a unitary switch as an arithmetic exponentiation switch. In the quantum logic circuit, if the adjoint gate pair is symmetric, the unitary switch function shows the balance function characteristic, and it takes 1 cycle operation to recover the original information reversibility. Conversely, if it is an asymmetric structure, it takes two cycle operations by the constant function. In this paper, we show that the problem of 2-cycle restoration according to the asymmetric structure when the hybrid MCT gate is realized with the ternary M-S gate can be solved by equivalent conversion of the asymmetric gate to the gate of the symmetric structure.

Function Embedding and Projective Measurement of Quantum Gate by Probability Amplitude Switch (확률진폭 스위치에 의한 양자게이트의 함수 임베딩과 투사측정)

  • Park, Dong-Young
    • The Journal of the Korea institute of electronic communication sciences
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    • v.12 no.6
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    • pp.1027-1034
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    • 2017
  • In this paper, we propose a new function embedding method that can measure mathematical projections of probability amplitude, probability, average expectation and matrix elements of stationary-state unit matrix at all control operation points of quantum gates. The function embedding method in this paper is to embed orthogonal normalization condition of probability amplitude for each control operating point into a binary scalar operator by using Dirac symbol and Kronecker delta symbol. Such a function embedding method is a very effective means of controlling the arithmetic power function of a unitary gate in a unitary transformation which expresses a quantum gate function as a tensor product of a single quantum. We present the results of evolutionary operation and projective measurement when we apply the proposed function embedding method to the ternary 2-qutrit cNOT gate and compare it with the existing methods.

Recent Development of Linear Scaling Quantum Theories in GAMESS

  • Choi, Cheol-Ho
    • Bulletin of the Korean Chemical Society
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    • v.24 no.6
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    • pp.733-738
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    • 2003
  • Linear scaling quantum theories are reviewed especially focusing on the method adopted in GAMESS. The three key translation equations of the fast multipole method (FMM) are deduced from the general polypolar expansions given earlier by Steinborn and Ruedenberg. Simplifications are introduced for the rotation-based FMM that lead to a very compact FMM formalism. The OPS (optimum parameter searching) procedure, a stable and efficient way of obtaining the optimum set of FMM parameters, is established with complete control over the tolerable error ε. In addition, a new parallel FMM algorithm, requiring virtually no inter-node communication, is suggested which is suitable for the parallel construction of Fock matrices in electronic structure calculations.

A Study on Characteristics of Null Pattern Synthesis Algorithm Using Quantum-inspired Evolutionary Algorithm (양자화 진화알고리즘을 적용한 널 패턴합성 알고리즘의 특성 연구)

  • Seo, Jongwoo;Park, Dongchul
    • Journal of the Korea Institute of Military Science and Technology
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    • v.19 no.4
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    • pp.492-499
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    • 2016
  • Null pattern synthesis method using the Quantum-inspired Evolutionary Algorithm(QEA) is described in this study. A $12{\times}12$ planar array antenna is considered and each element of the array antenna is controlled by 6-bit phase shifter. The maximum number of iteration of 500 is used in simulation and the rotation angle for updating Q-bit individuals is determined to make the individual converge to the best solution and is summarized in a look-up table. In this study we showed that QEA can satisfactorily synthesize the null pattern using smaller number of individuals compared with the conventional Genetic Algorithm.

Quantum Chemistry Based Arguments about Singlet Oxygen Formation Trends from Fluorescent Proteins

  • Park, Jae Woo;Rhee, Young Min
    • Rapid Communication in Photoscience
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    • v.5 no.2
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    • pp.18-20
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    • 2016
  • Through quantum chemical means, we inspect the energetics of the singlet oxygen formation with fluorescent proteins in their triplet excited states. By placing an oxygen molecule at varying distances, we discover that the energetic driving force for the singlet oxygen formation does not depend strongly on the chromophore $-O_2$ distance. We also observe that the chromophore vibrations contribute much to the energy gap modulation toward the surface crossing. Based on our computational results, we try to draw a series of rationalizations of different photostabilities of different fluorescent proteins. Most prominently, we argue that the chance of encountering a surface crossing point is higher with a protein with a lower photostability.

PCA-CIA Ensemble-based Feature Extraction for Bio-Key Generation

  • Kim, Aeyoung;Wang, Changda;Seo, Seung-Hyun
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.14 no.7
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    • pp.2919-2937
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    • 2020
  • Post-Quantum Cryptography (PQC) is rapidly developing as a stable and reliable quantum-resistant form of cryptography, throughout the industry. Similarly to existing cryptography, however, it does not prevent a third-party from using the secret key when third party obtains the secret key by deception, unauthorized sharing, or unauthorized proxying. The most effective alternative to preventing such illegal use is the utilization of biometrics during the generation of the secret key. In this paper, we propose a biometric-based secret key generation scheme for multivariate quadratic signature schemes, such as Rainbow. This prevents the secret key from being used by an unauthorized third party through biometric recognition. It also generates a shorter secret key by applying Principal Component Analysis (PCA)-based Confidence Interval Analysis (CIA) as a feature extraction method. This scheme's optimized implementation performed well at high speeds.