Effects of Impurity on the Ground—State Transitions of a Quantum Dot in Strong Magnetic Field

The low-lying spectra of parabolic quantum dots with or without an impurity at the center are investigated.While it has been known that the electron-electron interaction leads to ground-state transitions on magic values of angular momentum in a magnetic field. We show, in this paper, that the implantation of an impurity ion at the center can either enhance or suppress such transitions, depending on whether it is an acceptor or a donor ion.

Coexistance of C40 and C54 TiSi_2 during the solid statereaction of Ti/Mo/Si system

The effect of a 0.9 nm Mo interlayer at the interface of Ti film deposited on a Si substrate on phase formation of TiSi2 during annealing has been studied by using transmission electron micro-diffraction technique. When Ti/Mo/Si was an- nealed at low temperature as 550℃ for 30 mm in Ar ambient, a metastable phase. i.e., hexagonal C40 TiSi2, and the equilibrium phase. i.e., orthorhombic C54 TiSi2, were both detected. The experimental patterns of the C40 and C54 compare well with the simulated ones.

SEMI-BLIND CHANNEL ESTIMATION OF MULTIPLE-INPUT/MULTIPLE-OUTPUT SYSTEMS BASED ON MARKOV CHAIN MONTE CARLO METHODS

This paper addresses the issues of channel estimation in a Multiple-Input/Multiple-Output (MIMO) system. Markov Chain Monte Carlo (MCMC) method is employed to jointly estimate the Channel State Information (CSI) and the transmitted signals. The deduced algorithms can work well under circumstances of low Signal-to-Noise Ratio (SNR). Simulation results are presented to demonstrate their effectiveness.

A Spatiotemporal－Chaos－Based Encryption Having Overall Properties Considerably Better than Advanced Encryption Standard

Spatiotemporal chaos of a two-dimensional one-way coupled map lattice is used for chaotic cryptography.The chaotic outputs of many space units are used for encryption simultaneously. This system shows satisfactory cryp-tographie properties of high security, fast encryption (decryption) speed, and robustness against noise disturbances in communication channel. The overall features of this spatiotemporal-chaos-based cryptosystem are better than chaotic cryptosystems known so far, and also than currently used conventional cryptosystems, such as the Advanced Encryption Standard (AES).

Stability of Mixed Nash Equilibria in Symmetric Quantum Games

In bimatrix games the Bishop-Cannings theorem of the classical evolutionary game theory does not permitpure evolutionarily stable strategies (ESSs) when a mixed ESS exists. We find the necessary form of two-qubit initialquantum states when a switch-over to a quantum version of the game also changes the evolutionary stability of a mixedsymmetric Nash equilibrium.

MEASUREMENT-BASED ADMISSION CONTROL USING MULTIPLE TIME-SCALES TEST

A new measurement-based admission control algorithm to support Quality of Service(QoS) demand is proposed for soft real-time applications. In the algorithm, admission test is performed across Multiple Time-Scales (MTS) to accurately capture traffic fluctuation on various time-scales. By applying the QoS requirements directly to admission test, the MTS algorithm can properly meet the QoS target and maximize the bandwidth utilization.

Annealing behavior of ultrathin Mo layer located at interface or on surface of Ti-Si system

Annealing behavior, at different annealing temperatures, of an ultrathin Mo layer located between a Ti film and Si substrate or deposited on the top of sur -face of a Ti film was investigated by Rutherford baccscattering spectrometry (RBS), cross-sectional transmission electron microscopy (TEM) and energy dispersive X-ray spectrometry (EDS). In a Ti/Mo/Si structure, partially reacted film with layer struc- ture of Ti-rich silicide/TiSi2/(Mo, Ti)Si2 on a Si substrate was formed after 550℃ annealing for 30 min. The ratio of Mo to Ti in (Mo, Ti)Si2 layer decreases from ncar Si substrate upwards and becomes zero at about 20 nm away. In a Mo/Ti/Si structure, the surface Mo layer enhances the Si diffusion from the substrate during annealing. Mo bearing Ti rich silicide exists on the surface until 600℃ and then converts to (Mo, Ti)Si2 after 6500C annealing, and the atomic ratio of Mo to Ti decreases from the top surface into Ti silicide film, and becomes zero at about 30 nm away from the surface. In both cases of interface Mo and surface Mo layer, the atomic ratio of Mo to Ti in the region of (Mo, Ti)Si2 was found to be very low, with an average value of less than 0.2. Low content of Mo in Mo containing ternary sili.zide leads easily to the formation of the stable phase of C54 (Mo, Ti)Si2, which acts as a templatc for the formation of C54 TiSi2 beneath when Mo is deposited on the surface.

The Weak—Coupling of Bose—Einstein Condensates

The coherent characteristics of four trapped Bose-Einstein condensates (BEC) conjunct one by one in aring shape which is divided by two far off-resonant lasers, are studied. Four coupled Gross-Pitaevskii equations are usedto describe the dynamics of the system. Two kinds of self-trapping effects are discussed in the coupled BECs, and thephase diagrams for different initial conditions and different coupling strengths are discussed. This study can be used todetermine interaction parameters between atoms in BEC.

Investigation on the strain of SiGe/Si heteroepitaxial system during high temperature annealing byBiBS/Channeling

The influence of the high temperature processing on the strain stored in SiGe hetero-epilayer was studied by means of RBS/Channeling. Channeling angular scan along the ,< 110> axial direction in the (100) plane was used to characterize the tetragonal distortion in the SiGe strained layer. The strained crystal structure parameters were acquired by combining the determination of strain with the elasticity theory. It is shown that the strain stored in the SiGe epilayer has significantly change (relaxation factor from 0.023 to 0.84) after high temperature annealing. The potential strain relaxation mechanisms were discussed.

FAST CONVERGENT MONTE CARLO RECEIVER FOR OFDM SYSTEMS

The paper investigates the problem of the design of an optimal Orthogonal Fre- quency Division Multiplexing (OFDM) receiver against unknown frequency selective fading. A fast convergent Monte Carlo receiver is proposed. In the proposed method, the Markov Chain Monte Carlo (MCMC) methods are employed for the blind Bayesian detection without channel es- timation. Meanwhile, with the exploitation of the characteristics of OFDM systems, two methods are employed to improve the convergence rate and enhance the efficiency of MCMC algorithms. One is the integration of the posterior distribution function with respect to the associated channel parameters, which is involved in the derivation of the objective distribution function; the other is the intra-symbol differential coding for the elimination of the bimodality problem resulting from the presence of unknown fading channels. Moreover, no matrix inversion is needed with the use of the orthogonality property of OFDM modulation and hence the computational load is significantly reduced. Computer simulation results show the effectiveness of the fast convergent Monte Carlo receiver.