PA-40. Investigation of the Vitrification Process of Monatomic Lennard-Jones System with Free Surfaces

Le Nguyen Tue Minh and Vo Van Hoang.

Glass formation in simple monatomic LJ system with free surfaces has been studied by molecular dynamics (MD) simulations. Glass with two free surfaces is obtained by cooling from the melt. Atomic mechanism of glass formation is monitored via spatio-temporal arrangement of solid-like atoms in the system upon cooling. Solid-like atoms are detected using the Lindemann freezing-like criterion. Free surfaces significantly enhance atomic mobility in the system compared to that of the bulk and induce the formation of so-called layer structure of the interior of both liquid and glassy states. The temperature dependence of layering structure and the origin of layering is discussed. We found three characteristic temperatures related to the vitrification process. Temperature dependence of structure and various thermodynamic quantities of the system upon cooling is also presented and discussed via potential energy, radial distribution function (RDF), local bond-pair orders detected by Honeycutt-Andersen analysis, radial density profile and radial atomic displacement distributions.

Ho Khac Hieu(1), Pham Thi Minh Hanh(2) and Bui Dinh Hoi(1)

In this work, the statistical moment method has been used to study the effect of isotopic mass difference on extended X-ray absorption fine structure (EXAFS) Debye-Waller factor of crystalline germanium. We derived the temperature-dependent analytical expressions of the parallel mean-square relative displacement as well as the atomic mean square displacements of diamond-type crystals. Numerical calculations have been performed for two isotopes $^{70}$Ge and $^{76}$Ge in range of temperature from 20 K to 600 K. Our results are compared with previous studies by J. Purans et al. (Phys. Rev. Lett., 2008) and A. Sanson (Sol. Stat. Sci., 2010) and the good agreement is found.

Nguyen Thi Ha Loan and Hoang Van Quyet

In this paper we construct a g - Deformed crystal lattice vibration for kind difference atomic string, consider an energy spectrum of this vibration.

N T T Ha, H V Hung, N. V. Huy, N V Hong and P K Hung

Abstract: the static and dynamic properties of silica (SiO2) liquid are investigated by molecular dynamics simulation. To clarify the anomalous behavior of diffusion under compression we have traced the evolution (the breaking/reconstruct of the bond Si-O) of the basic structural units SiOx (x=4, 5, 6) with time under pressure from 0 to 25 GPa. The investigation reveals that diffusion of atoms is due to the transition Si[n] -> Si[n+1] (here Si[n] mean Si atom bond with n oxygen atoms). There are two types of transition: 1/ the transition causes the exchange the coordinated oxygen atoms; 2/ the transition only leads to forward-backward movement of oxygen atoms between SiOx units. The results show that the diffusion coefficient is proportional the rate of transitions and concentration of SiO5 units. Besides, diffusion coefficient is also depended strongly on correlation effect that is characterized by the distribution of the transitions in model.

Nguyen Quang Hoc and Dinh Quang Vinh

Using statistical moment method to study and calculate elasticity modules and elasticity constants of compounds of quantum crystals such as ArF, NeF, XeF, KrF and XeCl. Obtained results are compared with other calculations and experiments.

Phan Thi Thanh Hong(1) and Vu Van Hung(2)

The activation volume is the difference between the volume of system in states have atom diffuse and have not. In this study, we used the statistical moment method (SMM) with the four order approximation expansion of interaction potential energy, i.e, we have mentioned the effects of anharmonic lattice vibration, to calculate activation volumes for self-diffusion and impurity-diffusion in silicon crystal. Numerical results for Si, B, P and As diffusion in silicon are performed and compared to experimental data showing the good agreement.

Nguyen Thi Trang, Le Van Vinh and Pham Khac Hung

We present the simulation of amorphous aluminum and nano-crystal embedded in amorphous aluminum using molecular dynamics method with Sutton-Chen version of the embedded method potentials. The elastic and plastic properties of these materials were investigated by applying uniaxial deformation. The results show that the density and nano-crystalline size affect on the mechanical properties of materials.

Vu Van Hung(1) and Dang Thanh Hai(2)

Thermodynamic properties of rare-earth alloys have been studied using staistical moment method. The analytic expressions of the Helmholtz free energy and thermodynamic quantities were obtained. Present SMM results of nearest neighbor distance, linear thermal expansion coefficient and specific heats at constant pressure for Al2Ce3, AgCe3, Th(1-x)Cex ... are compared with the experimental results.

Vu Van Hung , Tran Thi Thuy Dung and Le Thi Thanh Huong

The moment method in statistical (SMM) dynamics is used to study the thermodynamic quantities of the CeO2 thin films taking into account the anharmonicity effects of the lattice vibrations and influence of high pressure. The nearest neighbor distance, thermal expansion coefficient, bulk moduli, specific heats at the constant volume and constant pressure of the CeO2 thin films are calculated as a function of the temperature and pressure The SMM calculations are performed by using the Buckingham potential for the CeO2 thin films .In the present study, the influence of temperature, pressure and thicknese on the thermodynamic quantities of CeO2 thin film have also been studied, using three different interatomic potentials We discuss the temperature, pressure, and thicknese dependences of the thermodynamic quantities of the CeO2 thin films and compare our calculated results with those of the experimental results.

N.T.T.Ha, B.T.V.Thao and P.K.Hung

In this paper we study the spatial heterogeneity and anomalous slowdown for diffusion in silica liquid by means of molecular dynamic simulation. The model consisting of 1998 particles and using the BKS potential has been constructed at the temperature from 2600 to 4500 K. Furthermore, we track the evolution of network units with x=4, 5 and 6 over different time. The simulation shows that the diffusivity depends strongly not only on the rate of the exchanging the coordinated oxygens, but also on the correlation effect. This effect is caused by the specific distribution of the exchanging coordinated oxygens through the space which leads to spatially heterogeneous dynamics in the liquid. To quantify the observed effects we have calculated the correlation coefficient F and h . Analyzing the temperature dependence of both quantities F and h we found that the slowdown in dynamics near glass transition point is ascribed from percolation of the domains where high frequent exchanging coordinated oxygens occurs.

P. The Nguyen(1), V. Thanh Ngo(2) and N. A. Viet(2)

In this work, we introduce a new model of shelf-organized system with including some physical interaction between the individuals, such as Morse and chemical potentials. The individuals can move freely in a square lattice of linear size L, and its velocity is determined by a 2D vector in the (x, y) plane with a constant absolute. The main parameter is the average velocity of the individuals which is considered as the order parameter of XY spin system. Using Monte-Carlo simulation method, we show clearly two phase transition at low and high noise ($\eta$). The transition at low noise corresponds to the schooling/flocking behavior, and that at high noise corresponds to the runaway behavior. The simulated results are in good agreement with the experimental observations of fishes.

Vu Ba Dung

Khuếch tán là một trong những quá trình cơ bản và phổ biến nhất của tự nhiên. Lý thuyết Fick cho rằng chiều của dòng khuếch tán luôn ngược chiều gradient nồng độ (quá trình khuếch tán xuôi - forward diffusion). Tuy nhiên, trong một số trường hợp có thể xảy ra quá trình khuếch tán ngược (backward diffusion), tức là dòng khuếch tán cùng chiều với với gradient nồng độ. Phương trình mô tả quá trình khuếch tán ngược và hệ số khuếch tán âm đã được các tác giả được đưa ra và thảo luận trên cơ sở lý thuyết nhiệt động lực học không thuận nghịch và. Từ đó các tác giả đã đưa ra một phương pháp khống chế ô nhiễm bụi và khí thải công nghiệp trong khí quyển.

Vu Ba Dung and Ta Thi Dung

The diffusion is the best elementally and general processes in nature. Fick law saw that diffusion currents are opposite direction of concentration gradient (forward diffusion). However, in some cases the backward diffusion could happening, that’s diffusion currents are the same direction of concentration gradient. Base on irreversible thermodynamic theory the backward diffusion is presented and discussed by authors, and once method of control of polluted atmosphere by dust and industrial exhaust are also recommended.

Bui Phuong Thuy(1,2), Trinh Xuan Hoang(1)

In vivo, folding of many proteins occurs during their synthesis in the ribosome and continues after they are released from the ribosomal exit tunnel. In this research, we investigate the confinement effects of the ribosome on the cotranslational folding of protein 1PGA by using a coarse-grained model and molecular dynamics simulation. The exit tunnel is modeled as a hollow cylinder attached to a plane surface whereas a Go-like model is adopted for the protein. Our results show that protein's secondary structures including the alpha-helix and the beta-hairpin are able to formed within the exit tunnel and the formation of tertiary structures follow two different folding routes.

D. T. Huong, N.T. L. Hoai and N. A. Viet

We analyze the effectiveness of HIV infection therapies with different types of drug. Here, the drug effect are modelled as a periodic function with the period of one day. It appears that linear-release drug is more appropriated than other therapies. The obtained result might be useful for HIV treatment.

Tran Phuoc Duy(1), Alejandro Giorgetti(2,3), Nguyen Ha Hung Chuong(2), Hoang Zung(4), Paolo Carloni(2)

G-protein-coupled receptors (GPCRs) are the largest membrane-bound receptor family expressed by mammalians (encompassing more than 1% of the genome). They are involved in an enormous variety of intra- and extracellular signaling, including detection of light, sense of smell, neurotransmission, inflammation, and cardiac and smooth muscle contractility [Kroeze et al., J Cell Sci 116,4867 (2003); Sakmar et al., Curr Opin Cell Biol 14, 189 (2002)]. Ligand (or photon) binding to GPCRs activates a cascade of events, producing an electrical signal as output. They are of utmost pharmaceutical relevance, being the targets of almost 30% of all marketed drugs [Landry and Gies, Fundam Clin Pharmacol 22, 1 (2008)]. The aim of this study is to perform a systematic and detailed analysis of sequence-structure relationships of known GPCR structures. A web-server for the automatic modeling and ligand docking of GPCRs at different activation states has been developed. Based on the modeling and docking results, we perform the MM/CG simulation for the obtained receptor/ligand complexes for checking the stability of the ligand in binding site.

Nguyen Ba Hung(1,2) , Trinh Xuan Hoang(2)

In recent years, extensive studies have indicated that the free energy landscape of proteins is largely determined by the symmetry of a tube and geometrical constraints played by the hydrogen bonds. In this study, we investigate the role of hydrophobic interaction in the folding of proteins in this presculpted free energy landscape. We consider two models for the hydrophobic interaction: the HP model for hydrophobic (H) and polar (P) sequences, and the Go model as an idealized system with optimized potentials for folding to a given native structure. Monte Carlo simulations are carried out for two sequences of length of 48 amino acids, whose ground states are a three-helix bundle and a GB1-like structure. We found that for systems of the same native state, folding of the HP sequence is much more complex than the Go model. Comparison of the two models gives us insights into the role of hydrophobic interaction and sequence specificity in protein folding.

T. A. Chu, D. H. Lien, N. A. Viet

it has been used since longtime some temperature terms for financial market, such as "hot", "cold", "iced". but there has not been built yet a model to measure the market temperature. as the continue of the previous work which has been presented about the boltzmann and gaussian model, here comes the idea about the information measurement for financial market. a simple model has been proposed, in which some characteristic parameters of financial market have been used to measure market temperature

Truong Thi Chinh(1), Dinh Van Thien(3), T.T.T Van(2) and Nguyen Ai Viet(2)

The pH dependence of the optical biosensor from DNA and semiconductor graphene nanoribbons (SGR) is investigated. Heller et al (Science 311, 508 (2006)) have demonstrated the first model of this kind of nano biosensors by wrapping a piece of double-stranded DNA around the surface of single-walled carbon nanotubes (CN). This new type of optical biosensor in the first time can be placed inside living cells and detect trace amounts of harmful contaminants using near infrared light. In our design model, instead of CN with cylinder shape we take semiconductor graphene nanoribbons (SGR) with flat geometry. Using the simple exciton theory in nanostructures, the periodic boundary conditions neglecting the edge effect, and the phenomena of B-Z structural phase transition of DNA, we investigate working principle and pH dependence of this new class of optical biosensor DNA-SGR responded to the presence of target ions. We’ve shown the range of parameters for workable conditions of this biosensor was indicated that the solution should have pH from 6 to 9, which is applicable for the living environments

To Thi Thao, Ngo Van Thanh, Do Thi Nga, Chu Thuy Anh and Nguyen Ai Viet

The discovery recently of neuroglobin (Ngb), expressing in the cytoplasm of nerve cells in the brain and in the retina of vertebrates, is a identified member of the globin superfamily. The function of neuroglobin depends not only on its structure, but also on mechanical properties. In this study, we combine the Zacharias model and Morse potential for investigating the flexibility of neuroglobin. Throughout the simple model, our results show the suitable with other works.

D. Tien Hoang(1), T. Hoa Vo(2), V. Thanh Ngo(3) and N. A. Viet(3)

We study the nature of the phase transition in the face centered cubic (FCC) lattice with the Ising spin glass model. With a standard Monte-Carlo method and the powerful Wang-Landau flat-histogram method, we carry out in this work intensive simulations with many value of p(%) being the ratio of number of ferromagnetic bonds and antiferromagnetic bonds. We show that the first-order transition has been destroyed with a tiny amount of ferromagnetic bond p ~ 0.01%. With increasing p, the antiferromagnetic phase changes to spin glass and then to ferromagnetic phase. Various physical quantities such as energy, specific heat, magnetization and susceptibility are shown and discussed

Vo Van On(1) and Pham Lan Anh(2)

In this paper, we investigate the spherically – symmetric pressure collapse of a white – black hole in the vector model of gravitational field from the point of view of an observer at infinity and on the surface of the star. The obtained results have many interesting differences compared with that in the spherically – symmetric pressure collapse of the black holes. We have also obtained the metric of space – time in the white - black hole in modified Eddington – Finkelstein coordinates and modified Kruskal – Szekeres coordinates.

Le Viet Hoa(1) and Le Duc Anh(2)

Isospin dependence of the pressure of asymmetric nuclear matter in the extended Nambu-Jona-Lasinio (ENJL) model is studied by means of the effective potential in the one-loop approximation. The equations of state (EOS) starting from the effective potential is investigated. Our numerical results show that the critical temperature for the phase liquid-gas transition decreases with the increasing neutron excess.

Nguyen Chinh Cuong

To solve the $\mu$ problem of Minimal Supersymmetric Standard Model (MSSM), single field $S$ is added to build Next Minimal Supersymmetric Standard Model (NMSSM). Vacuum enlarged with non-zero vevs of the neutral-even CP is the combination of $ H_u$, $ H_d$ and $S$. The scalar part of $\hat{S}$ combined with neutral scalar parts of $\hat{H}_u$ and $\hat{H}_d$ in the real parameters (CP violation passed) creates three neutral scalar particles including one particle of even CP and two particles of odd CP. The result shown that the higgs sector of NMSSM varies much compared with MSSM and it contains important information about the CP violation of this model.

Dang Trung Si and Nguyen Thanh Phong

We study the supersymetric seesaw model in a S_4 based flavor model. It has been shown that at the leading order, the model yields to exact tri-bimaximal pattern of the lepton mixing matrix and zero lepton-asymmetry of the decays of heavy right-handed neutrinos. By considering the renormalization group evolution (RGE) from high energy scale (GUT scale) to low energy scale (seesaw scale), the off-diagonal terms in the combination of the Dirac Yukawa-coupling matrix can be generated and the degeneracy of heavy right-handed Majorana neutrino masses can be lifted. As a result, the flavored leptogenesis successfully realized. We also investigate how the effective light neutrino mass m_{ee} associated with neutrinoless double beta decay can be predicted along with the neutrino mass hierarchies by imposing experimental data on the low-energy observables. We find a link between the leptogenesis and the neutrinoless double beta decay characterized by m_{ee} through a high energy CP phase, which is correlated with the low energy Majorana CP phases. It is also shown that the effects of RGE on leptonic mixing angles are negligible

Truong Trong Thuc and Nguyen Thanh Phong

We study the supersymetric seesaw model in a S4 based flavor model. It has been shown that at the leading order, the model yields to exact tri-bimaximal pattern of the lepton mixing matrix and zero lepton-asymmetry of the decays of heavy right-handed neutrinos. By introducing a soft-breaking term in Dirac-neutrino mass matrix, a non-zero Ue3 is generated leading to the non-zeros of mixing angle 13 and Dirac CP violating phase CP, and we also obtained the deviations of the values 12 and 23 from their tri-bimaximal values. In addition, non-zero lepton asymmetry from the decays of right-handed neutrinos is generated, as a result, by a reasonable choice of model parameters compatible with low-energy data, the baryon asymmetry of the Universe is successful generated through flavored leptogenesis

Nguyen Huy Thao(1), Tran Dinh Tham(2) and Dang Van Soa(3)

An attempt is made to present some experimental predictions of Randall-Sundrum (RS) model with the heavy radions. We calculate the total cross-section for photon-radion conversions in external electromagnetic fields, namely strong magetic fields, wave guide and resonant cavity. The radion mass is chosen in the range of Higgs mass in the standard model, the required VEV (Λф) is about 0.68 TeV. We have found some resonant conversions in which cross-sections are much enhanced, which can be measurable in current experiments.

Bui Minh Loc(1), Dao Tien Khoa(2), Dang Ngoc Thang(2), and Le Xuan Chung(2)

The two-channel coupling formalism was used to reproduce the proton elastic scattering and (p, n) charge exchange exciting 0+ isobaric analog state ((p, n)IAS) reaction data. The nucleon optical potential and (p, n)IAS form factor were calculated by folding model using the density- dependence CDM3Y6 interaction and nuclear ground state density from analysis of the high- energy 208Pb(p, p) data. Our result indicates that the neutron skin thickness and also the nuclear symmetry energy at low nuclear matter densities can be determined by precise measurements and a good description for (p, n)IAS.

Nguyen Quoc Hoan

We present solutions of Yang-Mills equations with two point color charge sources and for topological indices n > 2. The space distributions of corresponding field strengths and energy density are simulated and plotted. The dependence of the field strengths and the total energy on topological indices is discussed. By using the same algorithm of solving we obtain the solutions for the Yang-Mills field due to a series of color point charges which lie in a straight line.

Nguyen Van Thuan

In this paper, we analyze a non - Abelian extension of the Yang - Mills - Higgs action for the SU(2) group. We obtain a non - Abelian classical solution for the SU(2) Yang - Mills fields coupled with two Higgs fields. We also find the energy expression of this solution. Some particular cases of the solution are considered.

Pham Thuy Giang(1), Le Tho Hue(1), Do Thi Huong(1), Hoang Ngoc Long(1) and Nguyen Huy Thao(2)

We establish formulas to calculate lepton flavor violating processes in the economical supersymmetric 331 model such as branch ratios of Higgs decays to (muon, tauon) and tau to three muons. By numerical analysis these formulas, we also show that the first process can be detected in present experiments but the second is too small to detect.

Nguyen Suan Han(1) , Nguyen Nhu Xuan(2) , Phan Thi Giang(1)

By the Logunov-Tavkhelidze quasipotential equation the deduction of an eikonal representation for scattering amplitude of the spin ½ particles on smooth potentials is performed. The discussion proceeds within the framework of the two-component description, and on the basis of the Dirac equation.

Dao Vong Duc(1) and Nguyen Mong Giao(2)

In this work we consider a mechanism for the creation of particle mass in space-time with extradimensions. It is based on the periodicity condition dictated from the compactification of extradimensions. The resulting mass of each particle is completely determined by some function of compactification length. It is also shown that the exsistence of tachyon having negative squared mass is closely related to time-like extradimensions

Luu Thi Kim Thanh, Tran Thai Hoa, Nguyen Minh Vuong

We apply the q-deformed Bose – Einstein statistics distribution to determine Bose - Einstein condensation temperature, we obtained the result that Bose - Einstein condensation temperature not only depends on the concentration but also depends on parameters deformation q. Then the phase transformation tempearature of superconductor for Zinc is derived.

Cao Long Van(1), Dinh Xuan Khoa(2), Doan Quoc Khoa(3), Wieslaw Leoński(1), Nguyen Thanh Vinh(2)

A typical problem of Quantum Optics is the resonance interaction of several lasers with an atomic (molecular) system, where laser lights are fluctuating in amplitude and phase, and collisions between the elements of the system are frequently taken into account. Because of the very complicated (or even obscure) microscopic nature of all relevant relaxation mechanisms, they are modeled by classical time-dependent random processes. Thus, the dynamical equations describing the problem become stochastic differential equations. Except in certain specific cases, as in the case of the chaotic white noise, these equations cannot be solved in finite terms. When the coherence time of the noise (laser light or collisions) is comparable time scale of the atomic system, obtaining an exact solution of such stochastic equations is very difficult. One of the most useful stochastic models has been proposed by Wodkiewicz and co-workers [1, 2, 3, 4] and is based on the so-called pre-Gaussian process. It is composed of a finite number of independent two-step random telegraph signals. The strength of the pre-Gaussian formalism derives from the exact solubility of wide classes of stochastic equations. Even in the case of one random telegraph signal one can obtain several interesting results concerning various phenomena in Quantum Optics. In our talk we would like to present some of them.

Nguyen Thanh Vinh(1), Bui Dinh Thuan(1), Cao Long Van(2), Wieslaw Leoński(2)

Stephen Wolfram published in 1983 the first of a series of papers which investigate systematically a very basic but essentially unknown class of cellular automata, called elementary cellular automata. He published further in 2002 his result in a book A New Kind of Science, which leads to very important conclusion that the discoveries about cellular automata did not concern isolated facts, but also have significance for other disciplines of science [1]. On other hand, MATLAB language with a wide range of applications in solving technical problems is very useful in analyzing, visualizing and exploring data. In some cases it is even faster than traditional programming languages as C, C++, Fortran In this paper, we shall reconsider the system composed of a large number of two-level subsystem investigated in [2] which models various problems of contemporary physics and engineering, sometimes even social sciences. Several results obtained there are reproduced in a faster and effective way. In the next, we extend this model to the two-dimentional case, where some interesting results are obtained and discussed in detail. All calculations are realized by MATLAB language. Obtained results show the universality and effectiveness of CA formalism as a tool for dissipation investigations which is nicely demonstrated by MATLAB

Vo Tinh, Dang Huu Dinh, Truong Minh Duc

In this paper, the higher-order squeezing and the higher-order antibunching in two-mode nonlinear charge coherent states are studied. The analytical expressions of conditions for existing the higher-order squeezing and the higher-order antibunching are obtained. It is showed that these states exhibit all the higher-order squeezing, the higher-order antibunching behaviors. However, the higher-order antibunching may or may not exist depending on the parameters of these states.

Nguyen Ba An, Cao Thi Bich and Nung Van Don

Joint remote state preparation (JRSP) is a quantum network protocol which, by means of local operations and classical communication, allows a number of separate senders to cooperate in preparing a quantum state for a distant receiver, usually via shared maximal entanglement as the quantum channel. The security level of all the existing JRSP protocols is that any subgroups of the senders cannot identify the state to be prepared, but the whole group can. Here, we show that, in order to avoid leakage of full information to the whole group of senders when they all reveal their partial information to each other, non-maximal entanglement should be used together with judicious information splitting. As an illustration, we consider the case of two-sender JRSP of an arbitrary two-qubit state employing minimum non-local resource in terms of three Bell-like pairs. We design two explicit protocols. The first protocol requires the receiver to have an ancilla and to be capable of performing a quantum gate followed by a collective measurement on the ancilla and the part of a priori shared entanglement, while the second protocol does not at all. A surprising fact we find out is that the second protocol is not only simpler in execution but also succeeds with a higher probability than the first one. More interestingly, the second protocol’s security is absolute in the sense that the state of concern can by no means be reconstructed even though all the three participants (i.e., two senders plus a receiver) collude with each other.

Phan Hoang Chuong

Chuyển dộng Chaos, gồm chuyển động ziczac và dao động, tạo quỹ đạo xác suất. Trước đây đã xét chuyển động ziczac dạng khuyếch tán nhiệt, nay xét dao động với việc tìm nghiệm phương trình Schrodinger cho dao động tử với biến tọa độ ngẫu nhiên Wiener, sử dụng giải tích ngẫu nhiên đưa về phương trình Hermit, dùng phương pháp Monte-Carlo và khai triển Ito-Taylor tìm nghiệm trường hợp 1 chiều với nguồn độc lập thời gian.

Truong Minh Duc(1), Nguyen Thi Xuan Hoai(1) and Nguyen Ba An(2)

We introduce new nonclassical states by simultaneously adding arbitrary numbers of photons to both modes of the two-mode displaced squeezed state. Our states thus contain as a particular case those in [J. Phys. B 34, 1059 (2001)] in which only photons of either mode are added. We study various nonclassical behaviors of the new states. Especially, we also deal with the quasi-probabilistic distribution function of these states in phase space representation.

Truong Minh Duc(1), Tran Quang Dat(1) and Nguyen Ba An(2)

Trio coherent states were introduced in [1] and schemes for their generation as vibrational states of a trapped ion inside a crystal were proposed in [2]. To be useful in global quantum information processing, however, trio coherent states should be in form of three optical fields that can travel in any directions in open space. Here, we design a possible experimental scheme to produce such a free-traveling trio coherent state by using four cross-Kerr media, four 50:50 beam-splitters, two phase-shifters and three on/off detectors. We also discuss in detail the feasibility of our scheme. [1] N. B. An and T. M. Duc, J. Opt. B 4, 80 (2002). [2] N. B. An and T. M. Duc, Phys. Rev. A 66, 065401 (2002); H. S. Yi, N. B. An and J. Kim, Phys. Lett. A 315 , 6 (2003).

Nguyen Manh An, Nguyen Van Hoa and Nguyen Van Thoai

General relationship between the intensity of the input signal and the intensity of the reflected signal through a Symmetric Nonlinear Michelson Interferometer (SNMI) were calculated and investigated. That we can confirm that SNMI operating as an optical bistable device if we select the appropriate structural parameters. References [1]. Demtroder W (1982), Laser Spectroscopy, New York. [2]. Sakata H. (2001), “Photonic analog-to digital conversion by use of nonlinear Fabry -Perot resonators”. Appl.Phys., 40, 240-248 [3]. N. V. Hoa, H. Q. Quy, Proc. of The GVS6, Chemnitz, May 25-31 (2003). [4]. H. Q. Quy, V. N. Sau, N. V. Hoa, Commun.in Phys. Vol 13, No.3 (2003) pp. 157-164. [5]. H. Q. Quy, N. V. Hoa, Proc. of The GVS7, HaLong, March 28-April 3 (2004). [6]. N. V. Hoa, H. Q. Quy, V. N. Sau, Commun.in Phys. Vol 15, No.1 (2005) pp 6-12.

Nguyen Manh An, Nguyen Van Hoa and Nguyen Van Thoai

Symmetric Nonlinear Michelson Interferometer (SNMI) operating as optical bistable device has been theoretically investigated. The general output-input intensity relation is introduced for case the output signal transmitted through SNMI. The bistable characteristic (hysteresis) is calculated and presented for some cases the structural parameters were selected specifically. References [1]. Demtroder W (1982), Laser Spectroscopy, New York. [2]. Sakata H. (2001), “Photonic analog-to digital conversion by use of nonlinear Fabry-Perot resonators”. Appl.Phys., 40, 240-248 [3]. N. V. Hoa, H. Q. Quy, Proc. of The GVS6, Chemnitz, May 25-31 (2003). [4]. H. Q. Quy, V. N. Sau, N. V. Hoa, Commun.in Phys. Vol 13, No.3 (2003) pp. 157-164. [5]. H. Q. Quy, N. V. Hoa, Proc. of The GVS7, HaLong, March 28-April 3 (2004). [6]. N. V. Hoa, H. Q. Quy, V. N. Sau, Commun.in Phys. Vol 15, No.1 (2005) pp 6-12.

Ho Quang Quy(1) and Nguyen Thi Thanh Tam(2)

In this article, the nonlinear threshold of a nonlinear coupler is defined based on an investigation into the dependence of the power transfer efficiencies of a nonlinear coupler on the input intensity. The sorting of a sequence of weak and strong pulses by the nonlinear coupler is simulated.

Tran Hong Nghia, Hoang Van Hung, Nguyen Ngoc Ty, Le Van Hoang

We consider the affect of the distribution of molecular alignment to the quality of the molecular imaging. First, we calculate the high-order harmonic spectra of N2 by the Lewenstein model with consideration of the distribution of the molecular alignment and analyze the dependence of the HHG on the alignment angle. Then we extract the HOMO of N2 from the HHG spectra by the tomographic method and compare with the ones obtained by the same method from experimental HHG data. The results show that there is a distribution of alignment that gives a very good comparison between the N2 HOMO images obtained from the simulated and experimental data. This explains why the previous simulation with the perfect molecular alignment could not lead to suitable image of N2.

Le Cong Nhan

Microstructured optical fibers (MOF) are a new source for supercontinuum (SC) generation. The micro structure of MOF can confine the laser pulse in a small diameter of silica and the zero dispersion wavelength (WZD) favors the soliton propagation. Those enhance the non linear phenomena because a high excitation density is created and kept during the propagation. In this work, we study the dependence of SC spectrum on the fiber lengths and show the role of difference nonlinear phenomena like: self phase modulation, cross phase modulation, four wave mixing, Raman stimulation, soliton propagation…which are responsible for the SC generation.

Nguyen Van Hoa(1) and Dac Hoang Luat(2)

Chúng tôi sử dụng phương pháp toán tử FK để giải bài toán nguyên tử Hidro khi không có trường ngoài theo sơ đồ vòng lặp, kết quả bài toán hội tụ rất nhanh về nghiệm chính xác bằng số cho cả hàm sóng và năng lượng. Chúng tôi chỉ ra rằng tốc độ hội tụ của bài toán phụ thuộc vào tham số tự do. Vùng giá trị tối ưu của tham số tự do ( vùng cho tốc độ hội tụ cao nhât ) được chỉ ra rõ ràng cho từng trạng thái của nguyên tử Hidro (trạng thái cơ bản, trạng thái kích thích thứ nhất và thứ hai). Một điều kiện phổ quát để chọn tham số tự do được đưa ra, kết quả chọn tham số tự do theo điều kiện này khá phù hợp với vùng giá trị tối ưu của tham số tự do cho tốc độ hội tụ cao nhất.

Doan Tri Dung, Cao Huy Thien, and Tran Thoai Duy Bao

Polariton condensate is studied in the Gross-Pitaevskii equation approximation. The pattern formation in the polariton condensate is investigated under different conditions of pumping and interacting modes. A scenario of the polariton condensate is presented by mean of evolution of the statistical characteristics.

Le Thi Cam Tu, Hoang Van Hung, Nguyen Ngoc Ty, Le Van Hoang

We analyze the electron interference effect in the high-order harmonic spectra of CO2 molecule for not only the parallel but also the perpendicular components and show how to apply this effect to extracting the inter-atomic distance. The simulation gives a very good precision for the O-O distance and we propose a method for an experimental confirmation based on the simulated data.

Nguyen Thanh Son, Phan Ngoc Hung, Le Van Hoang

We review the Hurwitz's theorem proved in 1898 that every normed division algebra with an identity is isomorphic to one of the following four algebras (R, C, H and O) orresponding to the real numbers, the complex numbers, the quaternions and the octonions. First, we check the statement from this theorem that the product of the sum of n squares by the sum of n squares is the sum of n squares in a bilinear way only when n is equal to 1, 2, 4 or 8 by the numerical method. Then we discuss the relation of this theorem to the fundamental problem of physics such as the existence of the monopoles. In the 2-dimensional space there is no monopole field (the case of 1). In the 3-dimensional space the monopole is the Dirac's magnetic monopole (the case of 3). In the 5-dimensional space the monopole is the Yang's SU(2) monopole (the case of 4). The last is the case of 4 for the 9-dimensional space where the SO(8) monopole exists.

Nguyen Van Hop

In this paper, different from the Physical Review A 78, 012312 (2008), we have fully studied the quantum fidelity when performing quantum teleportation an unknown quantum state via the GHZ or W decoherence channel due to interaction with the environment. Our calculations indicate that the same decoherence channel, when preparing the GHZ state or W state as quantum channel, the GHZ state loses more quantum information than or less quantum information than the W state depends on the physical nature of the channel, type of decoherence channel and decoherence time. The results of the average fidelity is completely consistent with the quantum entanglement of quantum GHZ state or W state.

Le Thi Thu Phuong(1), Le Dinh(1), Huynh Vinh Phuc(2), Tran Cong Phong(3)

In this paper, we use the operator projection technique to obtain the general analytic expression for the absorption power of a electromagnetic wave caused by confined electrons in rectangular quantum wires (RQW). Optically detected magneto-phonon resonance (ODMPR) effect in a specific GaAs/AlAs RQW is investigated. Anomalous behaviors of the ODMPR spectra are discussed. From the graphs showing the dependence of the absorption power on the photon frequency, we obtain ODMPR line-widths as profiles of curves. Computational results show that the ODMPR line-widths are directly proportional to magnetic field, temperature and decrease with wire's size.

Le Canh Trung(1), Dinh Xuan Khoa(1), Nguyen Huy Bang(1), J. Szczepkowski(2), W. Jastrzębski (2), and P. Kowalczyk(3)

The alkali-metal diatomic molecules have been attractive for both theoreticians and experimentalists because they have a relatively simple electronic structure. Their electronic structure is frequently considered by theoreticians as a very convenient model for introducing approximations which can be further applied to more complex molecular systems. From the experimental point of view, alkali-metal diatomic molecules with their main absorption bands lying in the visible and UV regions are very convenient objects for investigations with modern laser spectroscopy techniques. Investigations of alkali-metal molecules have recently experienced additional impetus since the formation of molecular Bose-Einstein condensates [1]. As in several experimental techniques related to cold molecules involve optical excitation either in the formation or detection stages, a need of precise spectroscopic characterization for excited molecular states has arisen.

Among alkali-metal diatomic molecules, NaLi is particularly interested because it has permanent dipole moment, thus can therefore be manipulated with external electric fields. Experimental investigations for the NaLi molecule, however, encounter two dilemmatic problems. The first one is the spectral overlaps due to a large number of allowed electric dipole transitions between various rovibrational energy levels. The second one is the difficulty in producing NaLi molecules is gas phase due to a big difference in melting-point temperatures between Na and Li bulks. Up to date, number of studied electronic states is quite limited [3-8]. As was suggested by the Schawlow’s group, the problem for spectroscopic overlaps could be surmounted by using the so called polarization labelling spectroscopy (PLS) technique [2]. Although the polarization spectra are Doppler limited but they are greatly simplified due to labelling process.

In this work, we report our PLS observation for NaLi. Over 730 spectral lines in the 2111+ band up to near dissociation limit have been identified. To our knowledge, this is the first time the rotational structure of NaLi in the 21 state has been resolved.