Stationary entanglement of two atoms in a common reservoir

We study the dynamics of two entangled atoms interacting with a common structured reservoir. By means of the exact solution of atomic dynamics, we show a novel quantum interference controlled by the relative phase of initial entangled state of the atoms. The quantum interference has a great influence on trapped excited-state population and stationary entanglement of the atoms. In particular, we construct an explicit condition under which atomic stationary entanglement can grow over their initial value.     

Aircraft Trajectory Prediction Based on Modified Interacting Multiple Model Algorithm

In order to realize the aircraft trajectory prediction,a modified interacting multiple model(M-IMM) algorithm is proposed,which is based on the performance analysis of the standard interacting multiple model(IMM) algorithm.In the proposed M-IMM algorithm,a new likelihood function is defined for the sake of updating flight mode probabilities,in which the influences of interacting to residual’s mean error are taken into account and the assumption of likelihood function being a zero mean Gaussian function is discarded.Finally,the proposed M-IMM algorithm is applied to the simulation of the aircraft trajectory prediction,and the comparative studies are conducted to existing algorithms.The simulation results indicate the proposed M-IMM algorithm can predict aircraft trajectory more quickly and accurately.     

t-bit semiclassical quantum Fourier transform

Because of the difficulty of building a high-dimensional quantum register,this paper presents an implementation of the high-dimensional quantum Fourier transform(QFT)based on a low-dimensional quantum register.First,we define the t-bit semi- classical quantum Fourier transform.In terms of probability amplitude,we prove that the transform can realize quantum Fourier transformation,illustrate that the requirement for the two-qubit gate reduces obviously,and further design a quantum circuit of the transform.Combining the classical fixed-window method and the implementation of Shor’s quantum factorization algorithm,we then redesign a circuit for Shor’s algorithm,whose required computation resource is approximately equal to that of Parker’s.The requirement for elementary quantum gates for Parker’s algorithm is 3 O (logN),and the quantum register for our circuit re- quires t-1 more dimensions than Parker’s.However,our circuit is t2 times as fast as Parker’s,where t is the width of the window.     

Amplifying stationary quantum discord and entanglement between a superconducting qubit and a data bus by time-dependent electromagnetic field

We study the dynamics of quantum discord and entanglement between a superconducting qubit and a data bus,which is driven by a controllable time-dependent electromagnetic field,in the presence of phase decoherence and find that the quantum discord and entanglement remain at a stationary non-zero value for long time evolution.It is shown that the amount of stationary quantum discord and entanglement can be enhanced by applying the time-dependent electromagnetic field.     

Deleting a marked state in quantum database in a duality computing mode

In this article, we present a deletion algorithm in the duality computer that deletes a marked state from an even superposition of all basis-states with certainty. This duality computer deletion algorithm requires a single query, and this achieves exponential speedup over classical algorithm. Using a duality mode and recycling quantum computing, we provide a realization of this duality computer deletion algorithm in quantum computer.     

A scheme to implement the Deutsch-Josza algorithm on a superconducting charge-qubit quantum computer

We have studied the implementation of the Deutsch-Josza quantum algorithm in a superconducting charge-qubit quantum computer. Different from previous studies, we have used the inductance coupled system of You et al. The detailed pulse sequences have been designed for the four possible functions in a 2-qubit system. The result is generalized to an arbitrary n-qubit system. This scheme will be useful for practical implementation of the algorithm.     

Quantum Switching Based on the Nearest Neighbor Hamiltonian

This paper describes a quantum switching architecture for nearest neighbor coupling.An efficient quantum shear sorting (QSS) algorithm is used to reduce the number of time steps.For the QSS algorithm,the running complexity of the quantum switching architecture is polynomial in time with the nearest neighbor coupling and the implementation is less complex.The result shows that improved switching is extremely simple to implement using existing quantum computer candidates.     

Ab Initio Molecular Dynamics of Proteins

正We describe a theoretical approach based on fragment method for quantum mechanical calculation of proteins.In this approach,complete quantum mechanical calculation of protein energies in solvent is carried out by fragment which is then feed into molecular dynamics simulation to study protein dynamics.This approach extends computational study of protein dynamics to the fully quantum mechanical level,beyond tradiationl force field methods.Pt     

A quantum algorithm that deletes marked states from an arbitrary database

We present a general quantum deletion algorithm that deletes M marked states from an N-item quantum database with arbitrary initial distribution. The general behavior of this algorithm is analyzed, and analytic result is given. When the number of marked states is no more than 3N/4 , this algorithm requires just a single query, and this achieves exponential speedup over classical algorithm.     

Flat Connections on Quantum Bundles and Fractional Statistic in Geometric Quantization

It is shown that in the geometric quantization formulation fractional statistics in a quantized system of N indistinguishable particles in two spatial dimensions arise from the nontrivial cohomology of the flat connection on the quantum line bundle as well as from the nontrival homology of the configuration space. The propagator of an nonrelativistic interacting system with fractional statistics is derived.     

Quantum mechanical meet-in-the-middle search algorithm for Triple-DES

We present a quantum mechanical meet-in-the-middle search algorithm inosculating the quantum computing theory with crypt-analysis method and basing on the Grover’s algorithm and the meet-in-the-middle attack, which can solve the three-key triple-DES in O(56 256) steps and with O(256) memory cost. The computational complexity is apparently reduced, compared with that of the existing algorithms.     

A quantum algorithm for searching a target solution of fixed weight

To search for a target n-product Boolean vector of fixed weight d, we propose an important method involving the notion of a fixed-weight "vector label" accompanied with a vector label restoration algorithm. Based on these, we present a new quantum algorithm designed to search for a fixed-weight target whose computation complexity, specifically O (（Cdn+1）^1/2) , is better than that for a classical algorithm. Finally, we use the procedure to search for the NTRU private key as an example to verify the efficiency of the new algorithm in searching for fixed-weight target solutions.     

A quantum algorithm for the dihedral hidden subgroup problem based on lattice basis reduction algorithm

To optimize the algorithms for the dihedral hidden subgroup problem, we present a new algorithm based on lattice basis reduction algorithm. For n 〈 120, we reduce the dihedral hidden subgroup problem to shortest vector problem. A subroutine is given to get a transition quantum state by constructing a phase filter function, and then the measurement basis are derived based on the lattice basis reduction algorithm for solving low density subset sum problem. Finally, the parity of slope s is revealed by the measurement. This algorithm needs preparing mn quantum states, m qubits to store and O（n2） classical space, which is superior to existing algorithms.     

Dynamical resonance in F＋H2 chemical reaction and rotational excitation effect

Reaction resonance is a frontier topic in chemical dynamics research,and it is also essential to the understanding of mechanisms of elementary chemical reactions.This short article describes an im- portant development in the frontier of research.Experimental evidence of reaction resonance has been detected in a full quantum state resolved reactive scattering study of the F H2 reaction.Highly accurate full quantum scattering theoretical modeling shows that the reaction resonance is caused by two Feshbach resonance states.Further studies show that quantum interference is present between the two resonance states for the forward scattering product.This study is a significant step forward in our understanding of chemical reaction resonance in the benchmark F H2 system.Further experimental studies on the effect of H2 rotational excitation on dynamical resonance have been carried out.Dy- namical resonance in the F H2(j=1)reaction has also been observed.     

NMR experimental realization of seven-qubit D-J algorithm and controlled phase-shift gates with improved precision

In this study, we report the experimental reali-zation of seven-qubit Deutsch-Jozsa (D-J) algorithm and controlled phase-shift gates with improved precision using liquid state nuclear magnetic resonance (NMR). Theexperimental results have shown that transformations Uf in the seven-qubit D-J algorithm have been implemented with different pulse sequences, and whether f is constant orbalanced is determined by using only a single function call(Uf). Furthermore, we propose an experimental method tomeasure and correct the error in the controlled phase-shift gate that is simple and feasible in experiments, and can have precise phase shifts. These may offer the possibility ofsurmounting the difficulties of low signal-to-noise ratio(SNR) in multi-qubit NMR quantum computers, morecomplicated experimental techniques, and the increase ofgate errors due to using a large number of imperfect selec-tive pulses. These are also applied to more complicated quantum algorithms with more qubits, such as quantumFourier transformation and Shor抯 algorithm.     

A new construction for the statistical theory of the nonextensive systems

We propose a new statistical theory for classical and quantum small systems.It is a generalized scheme of the Boltzmann–Gibbs statistical theory by extending the Boltzmann–Gibbs statistical factor from infinite systems to finite systems based on the microcanonical ensemble distribution function and keeping this factor in all thermodynamic processes.We reconstruct the statistical theory for finite systems by obtaining the expression of the average particle number and the thermodynamic quantities such as entropy and specific heat,in the finite systems.We also explore the discontinuous phase transitions in the interacting classical nanoscale gases without the thermodynamic limit.     

Large-scale wind turbine blade design and aerodynamic analysis

Incorporating controlled elitism and dynamic distance crowding strategies, a modified NSGA-II algorithm based on a fast and genetic non-dominated sorting algorithm is developed with the aim of obtaining a novel multi-objective optimization design algorithm for wind turbine blades. As an example, a high-performance 1.5 MW wind turbine blade, taking maximum annual energy production and minimum blade mass as the optimization objectives, was designed. A 1/16-scale model of this blade was tested in a 12 m × 16 m wind tunnel and the experimental results validated the high performance. Moreover, both the computational fluid dynamics (CFD) method and a free-vortex method (FVM) were applied to calculating the aerodynamic performance, which was consistent with the experimental data. For completeness, the CFD and FVM were used to analyze the wake structure, and good and consistent results were obtained between them.     

Sampled-data Iterative Learning Control for Singular Systems

Sampled-data iterative learning control (SILC) for singular systems is addressed for the first time. With the introduction of the constrained relative degree, an SILC algorithm combined with a feedback control law is proposed for singular systems. Convergence of the algorithm is proved in sup-norm, while the conventional convergence analysis is in λ-norm. The final tracking error uniformly converges to a small residual set whose level of magnitude depends on the system dynamics and the sampling-period. Due to inequalities to estimate the level of the existing results of SILC, convergence is guaranteed not only at the sampling instants but on the entire operation interval, so that the inter-sample behavior is guaranteed, which is more practical for real implementation.     

Comparing the biological coherence of network clusters identified by different detection algorithms

Protein-protein interaction networks serve to carry out basic molecular activity in the cell. Detecting the modular structures from the protein-protein interaction network is important for understanding the organization, function and dynamics of a biological system. In order to identify functional neighbor- hoods based on network topology, many network cluster identification algorithms have been devel- oped. However, each algorithm might dissect a network from a different aspect and may provide dif- ferent insight on the network partition. In order to objectively evaluate the performance of four com- monly used cluster detection algorithms: molecular complex detection (MCODE), NetworkBlast, shortest-distance clustering (SDC) and Girvan-Newman (G-N) algorithm, we compared the biological coherence of the network clusters found by these algorithms through a uniform evaluation framework. Each algorithm was utilized to find network clusters in two different protein-protein interaction net- works with various parameters. Comparison of the resulting network clusters indicates that clusters found by MCODE and SDC are of higher biological coherence than those by NetworkBlast and G-N algorithm.     

Quantum information and many body physics with cold atoms

We review our recent theoretical advances in quantum information and many body physics with cold atoms in various external potential, such as harmonic potential, kagome optical lattice, triangular optical lattice, and honeycomb lattice. The many body physics of cold atom in harmonic potential is investigated in the frame of mean-field Gross-Pitaevskii equation. Then the quantum phase transition and strongly correlated effect of cold atoms in triangular optical lattice, and the interacting Dirac fermions on honeycomb lattice, are investigated by using cluster dynamical mean-field theory and continuous time quantum Monte Carlo method. We also study the quantum spin Hall effect in the kagome optical lattice.