Three-Dimensional Simulations of RESET Operation in Phase-Change Random Access Memory with Blade-Type Like Phase Change Layer by Finite Element Modeling

An optimized device structure for reducing the RESET current of phase-change random access memory （PCRAM） with blade-type like （BTL） phase change layer is proposed. The electrical thermal analysis of the BTL cell and the blade heater contactor structure by three-dimensional finite element modeling are compared with each other during RESET operation. The simulation results show that the programming region of the phase change layer in the BTL cell is much smaller, and thermal electrical distributions of the BTL cell are more concentrated on the TiN/GST interface. The results indicate that the BTL cell has the superiorities of increasing the heating efficiency, decreasing the power consumption and reducing the RESET current from 0.67mA to 0.32mA. Therefore, the BTL cell will be appropriate for high performance PCRAM device with lower power consumption and lower RESET current.

On Mutual Transform Between Number-Difference State and Phase State Corresponding to Operational Phase Operator

In the mutual transform between the number-difference state and the phase state corresponding to the operational phase operator we find that there exists an end-point ambiguousness. This problem can be avoided by Lighthill's method.

Comparison of Isobaric and Non-isobaric Operations on a Two-Phase Dynamic Model for PEFC Cathode Gas Diffusion Layer

Key words,： Two 1-D dynamical and isothermal models of cathode gas diffusion layer（GDL） with isobaric and non-isobaric operations for polymer electrolyte fuel cells（PEFCs） were developed and implemented in COMSOL Multiphysics v3.5.The artificial diffusion coefficient was introduced as well to make the numerical computation be stable.In the non-isobaric model,the pressure of gas mixture was obtained by summing up the governing equations of gaseous components,instead of Navier-Stoks equation.Comparison of the two models were carried out with the steady-states and dynamical simulations under given conditions.The corresponding analysis based on the simulated results was also given simultaneously.This paper is contributed to finding the differences between the isobaric and non-isobaric operation in the two-phase model of cathode GDL.

A Three-Stage Operational Amplifier for a Wide Range of Capacitive Loads

This paper presents a three-stage CMOS operational amplifier （opamp） that combines accuracy with stability for a wide range of capacitive loads. A so-called quenching capacitor is added to a multipath nested Miller compensation （MNMC） topology to obtain stability for a wide range of capacitive loads. Theoretical analysis and mathematical formulas are provided to prove the improvement in stability. A prototype of this frequency compen- sation scheme is implemented in a 0.7μm CMOS process. Measurement′s show that the amplifier can drive capaci- tive loads ranging from 100pF to 100/μF with a gain of 90dB and a minimum phase margin of 26°. The amplifier has a unity-gain bandwidth of 1MHz for a 100pF capacitive load. It employs a quenching capacitance of 18pF.

New representation of the multimode phase shifting operator and its application

Based on the rotation transformation in phase space and the technique of integration within an ordered product of operators, the coherent state representation of the multimode phase shifting operator and one of its new applications in quantum mechanics are given. It is proved that the coherent state is a natural language for describing the phase shifting operator or multimode phase shifting operator. The multimode phase shifting operator is also a useful tool to solve the dynamic problems of the mnltimode coordinate-momentum coupled harmonic oscillators. The exact energy spectra and eigenstates of such multimode coupled harmonic oscillators can be easily obtained by using the rnultimode phase shifting operator.

A New Kind of Two-Fold Integration Transformation in Phase Space and Its Uses in Weyl Ordering of Operators

We propose a new two-fold integration transformation in p-q phase space∫∫^∞-∞dpdq/π e^2i（p-x）（q-y）f（p,q）≡G（x,y）,which possesses some well-behaved transformation properties. We apply this transformation to the Weyl ordering of operators, especially those Q-P ordered and P-Q ordered operators.

Generation of unconventional geometric phase gates in ion trap-optical cavity system by squeezed operators

Based on squeezed operators this paper has implemented an ideal unconventional geometric quantum gate （GQG） in ion trap-optical cavity system by radiating the trapped ions with the cavity field of frequency ωc and an external laser field of frequency ωL. It can ensure that the gate time is shorter than the coherence time for qubits and the decay time of the optical cavity by appropriately tuning the ionic transition frequency ω0, the frequencies of the cavity mode ωc and the vibrational mode v. It has also realized the unconventional GQG under the influence of the cavity decay based on the squeezed-like operators and found that the present scheme works well for the smaller cavity decay by investigating the corresponding fidelity and success probability.

Phase Properties of Nonlinear Coherent States

Using the Pegg-Barnett fornalism we study the phase probability distributions and the squeezing effects ofmeasured phase operators in the nonlinear coherent states introduced by R.L. de Matos Filho and W. Vogel to describethe center-of mass motion of a trapped ion and the q-coherent states. Moreover, we have obtained the completenessrelation of nonlinear coherent states and proved that the q-Fock state |n>q introduced in many papers is, in fact, theusual Fock state.

Creating unconventional geometric phase gate using squeeze-like operator assisted by strong driving field

Based on the idea that a squeezing process can be thought of as a total cumulative effect of a large number of tiny squeezing processes, we define a squeeze-like operator with a time-dependent squeeze parameter. Applying this operator to and combining with a system which includes a two-photon interaction between two atoms and an initial vacuum cavity field, and resorting to a resonant strong driving classical field, we obtain an unconventional geometric phase gate with a shorter gating time.

Phase Properties of Two-Mode Squeezing-Rotating Entangled Representation

By virtue of the squeezing-rotating entangled representation, we mainly establish the new two-mode phase operator and phase angle operat, or, which is a general form including the foregoing formalist in two-mode Fock space. In addition, the corresponding phase distribution function is given in the entangled representation. In terms of this definition, we also analyze the phase behavior of some simple two-mode states such as squeezing-rotatlng coherent state, squeezing-rotating vacuum state, and so on. It is found that the results exactly agree with the foregoing phase theory.

Fluctuations and Squeezing for Measured Phase Operators of the J-C Model in the Kerr Medium

By using the theory of measured phase operator proposed by Barnett and Pegg, dynamic properties of the phase of a field are studied. The time evolution and squeezing of measured phase operators of a coherent field interacting with a two-level atom in the cavity with or without the Kerr medium are investigated. The influences of virtual cavity field on squeezing of measured phase operator are studied. Our numerical results show that the squeezing effects are clearly influenced by Kerr medium parameters, the field intensity, and the detuning. Moreover, the influence of the virtual-photon field makes more quantum noise in the evolution of measured phase operators. Key words Jaynes-Cummings model (JCM) - Kerr medium - measured phase operator - squeezing - virtual photon PACS 2001 4250Dv

Higher-Order Fluctuations and Measured Phase Operators in the Squeezed Thermal States

We study the higher order fluctuations and squeezing of quadrature operators in the squeezed thermal states. In terms of measured phase operators, we discuss the fluctuations and squeezing of phases in these states. We conclude that the condition of higher order squeezing for quadrature components of the field is order independent and the fluctuations of measured phase operators are temperature independent.

New < q,n|| Representation for Studing Two-Mode Nonlinear Phase Operator

A new complete and orthonormal < q,n|| representation is constructed in which Hradil’s two-mode phase operator R exhibits its phase behavior manifestly and can be put into R = Σ^(∞)_(q=-∞)Σ^(∞)_(n=0) ||q-1,n> < q, n||, which resembles S-G phase operator (N + l)^(-1/2a) = Σ^(∞)_(n=1|n–l > < n|). The corresponding phase state is also obtained, which is quaJified to make up a phase representation.

Phase Properties of Nonlinear Coherent States

Using the Pegg-Barnett formalism we study the phase probability distributions and the squeezing effects of measured phase operators in the nonlinear coherent states introduced by R.L. de Matos Filho and W. Vogel to describe the center-of mass motion of a trapped ion and the q-coherent states. Moreover, we have obtained the completeness relation of nonlinear coherent states and proved that the q-Fock state \n>(q) introduced in many papers is, in fact, the usual Fock state.

Atomic Coherent State,Entangled State and Phase Operator for Studying Interference Between Two Bose-Einstein Condensates

For studying the interference between two Bose-Einstein condensates we introduce the atomic coherentstate(ACS)in the Schwinger bosonic realization along with the phase operator to directly calculate the interferencepattern with steady relative phase cos φ.Eigenstates of the density operator of condensates are classified as A CS is alsodemonstrated.The entangled state representation is used in some calculations.

Properties of Phase and Their Evolutions in Damped Odd and Even Coherent States

The properties of measured phase operators in damped odd and even coherent states have been studied. The fluctuations associated with measured phase and their squeezing in these states are investigated. The phase properties in damped superposition coherent states are considered too with the help of measured phase operators. These fluctuations and their squeezing are affected by damping and evolve with time elapsing.

Optimization of the seismic processing phase-shift plus finite-difference migration operator based on a hybrid genetic and simulated annealing algorithm

Although the phase-shift seismic processing method has characteristics of high accuracy, good stability, high efficiency, and high-dip imaging, it is not able to adapt to strong lateral velocity variation. To overcome this defect, a finite-difference method in the frequency-space domain is introduced in the migration process, because it can adapt to strong lateral velocity variation and the coefficient is optimized by a hybrid genetic and simulated annealing algorithm. The two measures improve the precision of the approximation dispersion equation. Thus, the imaging effect is improved for areas of high-dip structure and strong lateral velocity variation. The migration imaging of a 2-D SEG/EAGE salt dome model proves that a better imaging effect in these areas is achieved by optimized phase-shift migration operator plus a finite-difference method based on a hybrid genetic and simulated annealing algorithm. The method proposed in this paper is better than conventional methods in imaging of areas of high-dip angle and strong lateral velocity variation.

On the Bosonic Phase Operator Realization for Josephson Hamiltonian Model

On the assumption that a Cooper pair acts as a Bose particle and based on the newly established <η|representation, which is the common eigenvector of two particles' relative position and total momentum, we introduce a mesoscopic Josephson junction Hamiltonian constituted by two-mode Bose phase operator and number-difference operator. The number-difference-phase uncertainty relation can then be set up, which implies the existence of Josephson current.

Ferroresonance at Open Phase Operating Conditions of Power Transformers

The reliability of electric supply to consumers is one of the most important factors that determine the requirements imposed on modem utility companies. This paper presents the results of investigation by computer software of the overvoltages resulting from a ferroresonance conditions in MV networks at open phase operating condition with and without connection to earth on source and load sides of distribution transformer. This overvoltage may reach 4.2 pu on one of the HV side of transformer unswitched phases. The results of the study show that ferroresonance overvoltage may be controlled by replacing fuses with circuit breakers on HV side to ensure switching-off all phases. Insertion of resistor or reactor in the neutral of source and loadsides of the transformer with 5% active load will help in suppressing overvoltages.