Projection of a quantum state on eigenstates of average Hamiltonian

A scheme for projecting an arbitrary quantum state on eigenstates of average Hamiltonian is described. As an experimental example, projection on entangled Bell states, which are eigenstates of specially constructed average Hamiltonian, is demonstrated for a system of two dipolar-coupled nuclear spins. The results of a direct and time-reversed evolution are added to average out the coherences between different eigenstates and accomplish the projection.     

Dissipative solitons driving and bound state control via parameter gradients

The effect of phase and intensity gradients on the motion of dissipative solitons in a nonlinear interferometer is investigated. We show how the forces exerted by parameter gradients on the solitons alter their interactions. Consequently, it is possible to tune the spectrum of soliton bound states via the introduction of proper spatial distribution of the system parameters. Furthermore, we show how the use of properly shaped parameter distributions can lead to a relevant reduction of the cross-talk between close by solitons in applications.     

Analytical and numerical investigations of displaced thermal state evolutions in a laser process

We investigate how displaced thermal states(DTSs) evolve in a laser channel. Remarkably, the initial DTS, an example of a mixed state, still remains mixed and thermal. At long times, they finally decay to a highly classical thermal field only related to the laser parameters κ and g. The normal ordering product of density operator of the DTS in the laser channel leads to obtaining the analytical time-evolution expressions of the photon number, Wigner function, and von Neumann entropy. Also, some interesting results are presented via numerically investigating these explicit time-dependent expressions.     

The self-consistent average phonon equation of state for ionic crystals

The self-consistent average phonon (SCAP) approximation was successful in describing the thermodynamic properties of monatomic solids. This formalism was extended to ionic crystals (specifically sodium chloride) at two levels of approximation: (1) the phonon frequencies replaced by a single average frequency, and (2) the phonon frequencies replaced by two average frequencies corresponding to the usual acoustic and optic phonons. In order to compare with earlier calculations and with experiments various forms of the interatomic potential (with polarization neglected) were used. The SCAP calculation is in good agreement with experiment at low and medium temperatures but underestimates the high temperature thermal expansion. It is concluded that the SCAP formalism with polarization included should give a good approximation to the thermodynamic properties of simple ionic crystals over the entire temperature range.     

Analytical energy gradients for dynamical simulations of trans polyacetylene chains within the Pariser-Parr-Pople Hamiltonian

Exact analytical energy gradients for the Pariser-Parr-Pople (PPP) Hamiltonian are derived. A comparison of computer times for dynamical simulations of trans-Polyacetylene (t-PA) using analytical and numerical gradients is given. The numerical method is shown to lead to serious difficulties both computationally and from the point of view of numerical accuracy. In fact, using the analytical method, it turned out that the computational effort for the gradient calculation is negligible compared to that for the SCF iteration in each time step of a simulation. On the other hand, using the numerical method the gradient calculation is the time consuming bottle-neck of a simulation. A previously presented method for the gradient calculation in the Hückel type Su-Shrieffer-Heeger (SSH) Hamiltonian which was thought to be approximative, is shown to be exact.     

Magnetic field gradients in solid state magic angle spinning NMR.

Magnetic field gradients have proven useful in NMR for coherence pathway selection, diffusion studies, and imaging. Recently they have been combined with magic angle spinning to permit high-resolution measurements of semi-solids, where magic angle spinning averages any residual dipolar couplings and local variations in the bulk magnetic susceptibility. Here we show the first examples of coherence pathway selection by gradients in dipolar coupled solids. When the gradient evolution competes with dipolar evolution the experiment design must take into account both the strength of the dipolar couplings and the means to refocus it. Examples of both homonuclear and heteronuclear experiments are shown in which gradients have been used to eliminate the need for phase cycling.     

高平均功率固体激光功率和光束质量关系研究进展

固体激光的一个重大发展方向和目标是实现“三高”(高平均功率、高光束质量和高效率)激光同时输出,结合相关研究工作和进展,着重论述了固体激光输出功率和光束质量的关系,给出了功率升高、光束质量非线性下降是当前“三高”固体激光研究的一个基本科学技术问题。围绕这一基本问题,评述了一些重要技术途径和手段,并探讨了实现高平均功率高光束质量固体激光输出的可能有效途径。     

Infinite average lifetime of an unstable bright state in the green fluorescent protein

The time evolution of the fluorescence intensity emitted by well-defined ensembles of green fluorescent proteins has been studied by using a standard confocal microscope. In contrast with previous results obtained in single-molecule experiments, the photobleaching of the ensemble is well described by a model based on Lévy statistics. By assuming the presence of thermally activated barriers, this simple model allows us to obtain information about their height distribution.     

高平均功率固体激光功率和光束质量关系研究进展

 固体激光的一个重大发展方向和目标是实现“三高”(高平均功率、高光束质量和高效率)激光同时输出,结合相关研究工作和进展,着重论述了固体激光输出功率和光束质量的关系,给出了功率升高、光束质量非线性下降是当前“三高”固体激光研究的一个基本科学技术问题。围绕这一基本问题,评述了一些重要技术途径和手段,并探讨了实现高平均功率高光束质量固体激光输出的可能有效途径。     

The effects of gradients on the diagnostic use of spectral features from laser compressed plasmas

The use of spectral features as diagnostics of the plasma temperature and density is studied using a non-LTE radiative transfer model, which solves the coupled statistical equilibrium and radiative transfer equation consistently. The effect of gradients on the hydrodynamic data, i.e. temperature and mass density, is studied to establish the accuracy of the diagnostic procedures.     

The microwave spectrum,harmonic force field,and ground state average structure of 1,1-dichloroethylene

The microwave spectra of several isotopic species of 1,1-dichloroethylene have been measured up to high J values and have been analyzed for rotational constants and quartic centrifugal distortion constants. An approximate harmonic force field for the molecule has been obtained by combining the centrifugal distortion constants with known vibrational data. The harmonic force field has been used together with the results of the present and other microwave studies to determine the ground state average molecular structure.     

Phase transition to the state with nonzero average helicity in dense neutron matter

The possibility of the appearance of the states with a nonzero average helicity in neutron matter is studied in the model with the Skyrme effective interaction. By providing the analysis of the self-consistent equations at zero temperature, it is shown that neutron matter with the Skyrme BSk18 effective force undergoes at high densities a phase transition to the state in which the degeneracy with respect to helicity of neutrons is spontaneously removed.     

Analytical approximation of the thermal and caloric equations of state for real gases over a wide density and temperature range

The thermal and caloric equations of state of the main components of gas mixtures normally used in calculations of gas dynamic processes, including combustion and detonation, as well as in problems of internal ballistics, are presented in an analytical form. The formulas obtained for the equations of state contain a relatively small number of parameters and provide an average error of approximation of less than 1% at temperatures from 500 to 2000–2500 K and densities up to the critical.     

Analytical description of the coherent state model for near vibrational and well deformed nuclei

Analytical formulas for the excitation energies as well as for the electric quadrupole reduced transition probabilities in the ground, beta and gamma bands were derived within the coherent state model for the near vibrational and well deformed nuclei. Numerical calculations were performed for 42 nuclei exhibiting various symmetries and therefore with specific properties. Comparison of the calculation results with the corresponding experimental data shows a good agreement. The parameters involved in the proposed model satisfy evident regularities being interpolated by smooth curves. Few of them, which fall out of the curves, are interpreted as signatures for a critical point in a specific phase transition. This is actually supported also by the figures showing the excitation energy dependence on the angular momentum. The formulas provided for energies and $B\left(E2\right)$ values are very simple, being written in a compact form, and therefore easy to be handled to explain the new experimental data.     

Analytical potential energy function and spectroscopy parameters for B~1Π state of KH

Multi-reference configuration interaction is used to produce potential energy curves(PECs) for the excited B1Π state of KH molecule.To investigate the correlation effect of core-valence electrons,five schemes are employed which include the different correlated electrons and different active spaces.The PECs are fitted into analytical potential energy functions(APEFs).The spectroscopic parameters,ro-vibrational levels,and transition frequencies are determined based on the APEFs and compared with available experimental and theoretical data.The molecular properties for B1Π obtained in this letter,which are better than those available in literature,can be reproduced with calculations using the suitable correlated electrons and active space of orbitals.     

Further developments of a general method for deducing average hourly insolations from average daily insolations

Summary The hourly solar-radiation values, global and diffuse, recorded during nine years in the town of Genua and at Monte Capellino and during seven years in the town of Macerata, in Italy, have been used to find simple expressions which give the hourly and daily solar irradiations in average sky conditions. It is then shown how the long-term average hourly, direct and diffuse, irradiation can be deduced with good accuracy by using, solely, the knowledge of the long-term average daily, direct and diffuse, irradiations, respectively. The long-term averages have been calculated, with an original method, on a time basis of six days instead of the monthly time basis, as is usual in the literature. Finally, the correlation between long-term averages of diffuse and global solar radiation is analysed and discussed.

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Riassunto L'analisi dei valori orari della radiazione solare, globale e diffusa, registrati per nove anni nella città di Genova e sul Monte Capellino e per sette anni nella città di Macerata, in Italia, ha permesso di trovare semplici espressioni che danno i valori degl'irraggiamenti solari, orari e giornalieri, in condizioni di cielo medie. è quindi mostrato come il valore orario della radiazione diretta e diffusa, mediato su tempi lunghi, possa essere dedotto, con buona approssimazione, dalla sola conoscenza del valore giornaliero della radiazione, rispettivamente diretta e diffusa, mediato su tempi lunghi. Le medie su tempi lunghi sono state calcolate applicando una metodologia originale, sulla base di periodi di sei giorni invece che su quelle, abituale nella letteratura, di periodi di un mese. Infine è stata analizzata e discussa la correlazione fra i valori giornalieri di radiazione diffusa, mediati su tempi lunghi, e i valori orari di radiazione globale, pure mediati su tempi lunghi.

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Work supported by CNR-Progetto Finalizzato Energetica, S.P. RERE, Tema N, under contract 80.00936.92.     

Analytical model of equation of state for polydisperse fluid of adhesive spherical particles

An analytical model of the equation of state is presented for the polydisperse fluid of adhesive colloidal particles. The model is based on the mean-spherical approximation solution of the Ornstein-Zernike equation for a multicomponent hard sphere Yukawa fluid in which the Yukawa tails are sufficiently short range and strong. In particular, assuming that distributions of diameters and ‘charges’ of particles are described by the Schulz function, the analytical expressions for the compressibility and the pressure for the intrinsically polydisperse fluid are given in terms of simple functions of the packing fraction, the adhesion parameter and the Schulz distribution parameter.     

Unitary and analyticity bounds on average multiplicity and average transverse momentum

An upper bound on the partially integrated inclusive cross section is obtained at high energy from unitarity and analyticity assumptions which are to be expected for a two-body scattering amplitude that satisfies the Mandelstam representation. This result is analogous to the fixed-angle bound on two-body scattering amplitudes derived by Kinoshita, Loeffel and Martin. The bound leads to strong constraints on the average multiplicity, the average transverse momentum and the total cross section; in particular $\text{〈n〉〈p}{}_{\mathrm{<mtext>T</mtext><mtext>〉\sigma </mtext>}}{}_{\mathrm{T}}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{?}\text{const}\text{(}\text{ln}\text{s)}{}^2\text{(}\text{ln ln}\text{s)}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$. According to this, the energy dependence of average multiplicity and average transverse momentum favors logarithmic growth, at most.     

MCSCF study of the spin-orbit coupling in OH (X 2Π i )

Full-valence MCSCF calculations were performed for the X ²Π _i state of OH in that it was hoped that these would predict the spin-orbit coupling A(r) to within a few tenths of a wavenumber over the entire range of r. The functional form was correct but the actual values did not meet our expectations. We briefly considered higher-order relativistic corrections.

A universal even-tempered basis set was tested relative to an ‘extended’, optimized basis. The universal basis set did remarkably well and highlighted significant r-dependent and, presumably, state dependent problems with the smaller basis.