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1.
Deep optical lattices are considered, in each site of which there are many Bose condensed atoms. By the resonant modulation of trapping potentials, it is possible to transfer a macroscopic portion of atoms to the collective nonlinear states corresponding to topological coherent modes. Entanglement can be generated between these modes. By varying the resonant modulating field, it is possible to effectively regulate entanglement production in this multimode multitrap system of Bose condensates. 相似文献
2.
Punctuated evolution due to delayed carrying capacity 总被引:1,自引:0,他引:1
A new delay equation is introduced to describe the punctuated evolution of complex nonlinear systems. A detailed analytical and numerical investigation provides the classification of all possible types of solutions for the dynamics of a population in the four main regimes dominated respectively by: (i) gain and competition, (ii) gain and cooperation, (iii) loss and competition and (iv) loss and cooperation. Our delay equation may exhibit bistability in some parameter range, as well as a rich set of regimes, including monotonic decay to zero, smooth exponential growth, punctuated unlimited growth, punctuated growth or alternation to a stationary level, oscillatory approach to a stationary level, sustainable oscillations, finite-time singularities as well as finite-time death. 相似文献
3.
Bose systems, subject to the action of external random potentials, are considered. For describing the system properties, under the action of spatially random potentials of arbitrary strength, the stochastic mean-field approximation is employed. When the strength of disorder increases, the extended Bose-Einstein condensate fragments into spatially disconnected regions, forming a granular condensate. Increasing the strength of disorder even more transforms the granular condensate into the normal glass. The influence of time-dependent external potentials is also discussed. Fastly varying temporal potentials, to some extent, imitate the action of spatially random potentials. In particular, strong time-alternating potential can induce the appearance of a nonequilibrium granular condensate. 相似文献
4.
V. I. Yukalov E. P. Yukalova 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,55(1):93-99
The method of self-similar factor approximants is applied to calculating
the critical exponents of the O(N)-symmetric ϕ4 theory and of the
Ising glass. It is demonstrated that this method, being much simpler than
other known techniques of series summation in calculating the critical
exponents, at the same time, yields the results that are in very good
agreement with those of other rather complicated numerical methods. The
principal advantage of the method of self-similar factor approximants is
the combination of its extraordinary simplicity and high accuracy. 相似文献
5.
The problem of extrapolation and interpolation of asymptotic series is considered. Several new variants of improving the accuracy
of the self-similar approximants are suggested. The methods are illustrated by examples typical of chemical physics, when
one is interested in finding the equation of state for a strongly interacting system. A special attention is payed to the
study of the basic properties of fluctuating fluid membranes. It is shown that these properties can be well described by means
of the method of self-similar approximants. For this purpose, the method has been generalized in order to give accurate predictions
at infinity for a function, whose behavior is known only at the region of its variable close to zero. The obtained results
for fluctuating fluid membranes are in good agreement with the known numerical data. 相似文献
6.
A. J. Coleman E. P. Yukalova V. I. Yukalov 《International journal of quantum chemistry》1995,54(4):211-222
The reduction of the N-particle problem to the 2- and 1-particle problems is discussed, and the relation between the statistics of particles and the properties of the pairon distribution is studied. It turns out that not all levels of the pairon spectra can be occupied. A simple way of defining the pairon distribution is suggested. The spectra of the reduced Hamiltonian with power-law interaction potentials are analyzed. The bound states are calculated by the method of self-similar approximation, the accuracy of which is compared with and shown to be better than that of the quasi-classical approximation. © 1995 John Wiley & Sons, Inc. 相似文献
7.
V. I. Yukalov E. P. Yukalova D. Sornette 《The European physical journal. Special topics》2012,205(1):313-354
A class of models is introduced describing the evolution of population species whose carrying capacities are functionals of
these populations. The functional dependence of the carrying capacities reflects the fact that the correlations between populations
can be realized not merely through direct interactions, as in the usual predator-prey Lotka-Volterra model, but also through
the influence of species on the carrying capacities of each other. This includes the self-influence of each kind of species
on its own carrying capacity with delays. Several examples of such evolution equations with functional carrying capacities
are analyzed. The emphasis is given on the conditions under which the solutions to the equations display extreme events, such
as finite-time death and finite-time singularity. Any destructive action of populations, whether on their own carrying capacity
or on the carrying capacities of co-existing species, can lead to the instability of the whole population that is revealed
in the form of the appearance of extreme events, finite-time extinctions or booms followed by crashes. 相似文献
8.
Double-well optical lattices are considered, each cite of which is formed by a double-well potential. The lattice is assumed
to be in an insulating state and order and disorder are defined with respect to the displacement of atoms inside the double-well
potential. It is shown that in such lattices, in addition to purely ordered and disordered states, there, can exist an intermediate
mixed state, where, inside a generally ordered lattice, there appear disordered regions of mesoscopic size. 相似文献
9.
The method of self-similar factor approximants is shown to be very convenient for solving different evolution equations and boundary-value problems typical of physical applications. The method is general and simple, being a straightforward two-step procedure. First, the solution to an equation is represented as an asymptotic series in powers of a variable. Second, the series are summed by means of the self-similar factor approximants. The obtained expressions provide highly accurate approximate solutions to the considered equations. In some cases, it is even possible to reconstruct exact solutions for the whole region of variables, starting from asymptotic series for small variables. This can become possible even when the solution is a transcendental function. The method is shown to be more simple and accurate than different variants of perturbation theory with respect to small parameters, being applicable even when these parameters are large. The generality and accuracy of the method are illustrated by a number of evolution equations as well as boundary value problems. 相似文献
10.
Double-well optical lattice in an insulating state is considered. The influence of atomic vibrations and mesoscopic disorder on the properties of the lattice are studied. Vibrations lead to the renormalization of atomic interactions. The occurrence of mesoscopic disorder results in the appearance of first-order phase transitions between the states with different levels of atomic imbalance. The existence of a nonuniform external potential, such as trapping potential, essentially changes the lattice properties, suppressing the disorder fraction and rising the transition temperature. 相似文献