共查询到20条相似文献,搜索用时 10 毫秒
1.
A. Sojasi M. Mohsenzadeh M. V. Takook E. Yusofi 《International Journal of Theoretical Physics》2010,49(10):2409-2416
The main goal of this paper is to derive the primordial power spectrum for the scalar perturbations generated as a result of quantum fluctuations during an inflationary period by an alternative approach of field quantization, i.e. Krein space quantization (Gazeau et al. in Class. Quantum Gravity 17:1415, 2000; Takook in Int. J. Mod. Phys. 11:509, 2002; Rouhani and Takook in Int. J. Theor. Phys. 48:2740, 2009). The spectrum of scalar curvature perturbations are calculated in the slow roll approximation. 相似文献
2.
The Schrödinger equation is solved exactly for some well known potentials. Solutions are obtained reducing the Schrödinger equation into a second order differential equation by using an appropriate coordinate transformation. The Nikiforov-Uvarov method is used in the calculations to get energy eigenvalues and the corresponding wave functions. 相似文献
3.
We investigate the possibility of inducing the cosmological constant from extra dimensions by embedding our four-dimensional
Riemannian space-time into a five-dimensional Weyl integrable space. Following the approach of the space-time-matter theory
we show that when we go down from five to four dimensions, the Weyl field may contribute both to the induced energy-tensor
as well as to the cosmological constant Λ, or more generally, it may generate a time-dependent cosmological parameter Λ(t). As an application, we construct a simple cosmological model in which Λ(t) has some interesting properties. 相似文献
4.
The thermodynamic behavior of the Bose–Hubbard model is solved for any temperature and any chemical potential. It is found that there is a range of critical coupling strengths
c1 <
c2 <
c3 < in this model. For coupling strengths between
c,k
and
c,k+1, Bose–Einstein condensation is suppressed at densities near the integer values = 1,...,k with an energy gap. This is known as a Mott insulator phase and was previously shown only for zero temperature. In the context of ultra-cold atoms, this phenomenon was experimentally observed in 2002(1) but, in the Bose–Hubbard model, it manifests itself also in the pressure-volume diagram at high pressures. It is suggested that this phenomenon persists for finite-range hopping and might also be experimentally observable. 相似文献
5.
As is well known, the exact evolution equation of the curvature perturbation plays a very important role in investigation of the inflaorresponding exacttion power spectrum of the flat universe. However, the c extension for the non-flat universes has not yet been given clearly. Interest in the non-flat, specially closed, universes has been aroused recently. The need for this extension is pressing. We start with the most elementary physical consideration and obtain finally this exact evolution equation of the curvature perturbation for the non-flat universes, as well as the evolutionary controlling parameter and the exact expression of the variable mass in this equation. We approximately perform a primitive and immature analysis on the power spectrum of non-flat universes. This analysis shows that the exact evolution equation of the curvature perturbation for the non-flat universes is very complicated, and we need to carry out many numerical and analytic works for this new equation in the future to judge whether the universe is fiat or closed by comparison of theories with observations. 相似文献
6.
Russian Physics Journal - Approximate analytical and numerical solutions of the three-dimensional Logunov–Tavkhelidze equation are found for the spherically symmetric case. Solutions are... 相似文献
7.
The analytical solution of gradual change media in two-dimensional free space is studied. Using separation of variables, the solution of electromagnetic wave in time-varying media, which is an exponential function of time, is derived in two-dimensional space. The rationality of the solution is verified indirectly. According to the solution, the figures of the wave are depicted. Based on these figures, the character of the wave in time-varying media is obtained, which shows frequency shift and changes of phase velocity and amplitude. 相似文献
8.
Xiao-Yan Zhang Ji-Suo Wang Xiang-Guo Meng Jie Su 《International Journal of Theoretical Physics》2009,48(2):535-544
Using the coherent state representation of Wigner operator and the technique of integration within an ordered product (IWOP)
of operators, the Wigner functions of the Klauder-Perelomov coherent states (KP-CSs) for the pseudoharmonic oscillator (PHO)
are obtained and the variations of the Wigner functions with the parameters k and z are discussed. Moreover, the tomograms of the KP-CSs for the PHO are calculated by virtue of intermediate coordinate-momentum
representation in quantum optics.
Project 10574060 supported by the National Natural Science Foundation of China and project X071049 supported by Science Foundation
of Liaocheng University. 相似文献
9.
Exact Solutions of the Klein-Gordon Equation with a New Anharmonic Oscillator Potential 总被引:2,自引:0,他引:2 下载免费PDF全文
We solve the Klein-Cordon equation with a new anharmonic oscillator potential and present the exact solutions. It is shown that under the condition of equal scalar and vector potentials, the Klein-Cordon equation could be separated into an angular equation and a radial equation. The angular solutions are the associated-Legendre polynomial and the radial solutions are expressed in terms of the confluent hypergeometric functions. Finally, the energy equation is obtained from the boundary condition satisfied by the radial wavefunctions. 相似文献
10.
Giuseppe Castagnoli 《International Journal of Theoretical Physics》2009,48(12):3383-3395
Quantum algorithms require less operations than classical algorithms. The exact reason of this has not been pinpointed until
now. Our explanation is that quantum algorithms know in advance 50% of the solution of the problem they will find in the future.
In fact they can be represented as the sum of all the possible histories of a respective “advanced information classical algorithm”.
This algorithm, given the advanced information (50% of the bits encoding the problem solution), performs the operations (oracle’s
queries) still required to identify the solution. Each history corresponds to a possible way of getting the advanced information
and a possible result of computing the missing information. This explanation of the quantum speed up has an immediate practical
consequence: the speed up comes from comparing two classical algorithms, with and without advanced information, with no physics
involved. This simplification could open the way to a systematic exploration of the possibilities of speed up. 相似文献
11.
《理论物理通讯》2015,(9)
The exact analytical solution of the Klein–Gordon equation for the spin-0 particles in the generalized Woods–Saxon potential is presented. The bound state energy eigenvalues and corresponding wave functions are obtained in the closed forms. The correlations between the potential parameters and energy eigenvalues are examined for π0particles. 相似文献
12.
Mohsen Daeimohamad Fardin Kheirandish Khaled Saeedi 《International Journal of Theoretical Physics》2011,50(1):171-180
The dissipative quantum dynamics of a harmonic oscillator in the presence of a deformed bath is investigated. The deformed
bath is modelled by a collection of deformed quantum harmonic oscillators as a generalization of Hopfield model. The transition
probabilities between energy levels of the oscillator are obtained perturbatively and discussed. 相似文献
13.
Boris Gutkin 《Communications in Mathematical Physics》2001,217(1):33-53
We consider classical billiards on surfaces of constant curvature, where the charged billiard ball is exposed to a homogeneous,
stationary magnetic field perpendicular to the surface.
We establish sufficient conditions for hyperbolicity of the billiard dynamics, and give a lower estimation for the Lyapunov
exponent. This extends our recent results for non-magnetic billiards on surfaces of constant curvature. Using these conditions,
we construct large classes of magnetic billiard tables with positive Lyapunov exponents on the plane, on the sphere and on
the hyperbolic plane.
Received: 7 April 2000 / Accepted: 19 September 2000 相似文献
14.
Babatunde James Falaye 《Few-Body Systems》2012,53(3-4):563-571
The relativistic Klein–Gordon equation with equal scalar and vector spherically asymmetrical singular oscillators is solved using the asymptotic iteration method. The energy eigenvalues equation and the corresponding wave functions are obtain explicitly. It was found that the asymptotic iteration method provides the closed-forms for the energy eigenvalues as well as the eigenfunctions. The non-relativistic limit ${c \rightarrow \infty}$ of the energy spectrum, where c is the speed of light, have also been discussed. 相似文献
15.
Florin Diacu Slim Ibrahim Crystal Lind Shengyi Shen 《Communications in Mathematical Physics》2016,346(3):839-875
We obtain a natural extension of the Vlasov–Poisson system for stellar dynamics to spaces of constant Gaussian curvature \({\kappa \ne 0}\): the unit sphere \({\mathbb S^2}\), for \({\kappa > 0}\), and the unit hyperbolic sphere \({\mathbb H^2}\), for \({\kappa < 0}\). These equations can be easily generalized to higher dimensions. When the particles move on a geodesic, the system reduces to a 1-dimensional problem that is more singular than the classical analogue of the Vlasov–Poisson system. In the analysis of this reduced model, we study the well-posedness of the problem and derive Penrose-type conditions for linear stability around homogeneous solutions in the sense of Landau damping. 相似文献
16.
Carlo Cafaro 《International Journal of Theoretical Physics》2008,47(11):2924-2933
A new information-geometric approach to chaotic dynamics on curved statistical manifolds based on Entropic Dynamics (ED) is
proposed. It is shown that the hyperbolicity of a non-maximally symmetric 6N-dimensional statistical manifold ℳ
s
underlying an ED Gaussian model describing an arbitrary system of 3N degrees of freedom leads to linear information-geometric entropy growth and to exponential divergence of the Jacobi vector
field intensity, quantum and classical features of chaos respectively. 相似文献
17.
We examine the thermal conductivity and bulk viscosity of a one-dimensional (1D) chain of particles with cubic-plus-quartic
interparticle potentials and no on-site potentials. This system is equivalent to the FPU-α
β system in a subset of its parameter space. We identify three distinct frequency regimes which we call the hydrodynamic regime, the perturbative regime and the collisionless regime. In the lowest frequency regime (the hydrodynamic regime) heat is transported ballistically by long wavelength sound modes.
The model that we use to describe this behaviour predicts that as ω→0 the frequency dependent bulk viscosity,
, and the frequency dependent thermal conductivity,
, should diverge with the same power law dependence on ω. Thus, we can define the bulk Prandtl number,
, where m is the particle mass and k
B
is Boltzmann’s constant. This dimensionless ratio should approach a constant value as ω→0. We use mode-coupling theory to predict the ω→0 limit of Pr
ζ
. Values of Pr
ζ
obtained from simulations are in agreement with these predictions over a wide range of system parameters. In the middle frequency
regime, which we call the perturbative regime, heat is transported by sound modes which are damped by four-phonon processes. This regime is characterized by an intermediate-frequency
plateau in the value of
. We find that the value of
in this plateau region is proportional to T
−2 where T is the temperature; this is in agreement with the expected result of a four-phonon Boltzmann-Peierls equation calculation.
The Boltzmann-Peierls approach fails, however, to give a nonvanishing bulk viscosity for all FPU-α
β chains. We call the highest frequency regime the collisionless regime since at these frequencies the observing times are much shorter than the characteristic relaxation times of phonons. 相似文献
18.
Stephen C. Anco 《International Journal of Theoretical Physics》2008,47(3):684-695
A spinor derivation is presented for quasilocal mean-curvature mass of spacelike 2-surfaces in General Relativity. The derivation
is based on the Sen-Witten spinor identity and involves the introduction of novel nonlinear boundary conditions related to
the Dirac current of the spinor at the 2-surface and the tangential flux of a boundary Dirac operator, as well the use of
a spin basis adapted to the mean curvature frame of the 2-surface normal space. This setting may provide an alternative approach
to a positivity proof for mean-curvature mass based on showing that Witten’s equation admits a spinor solution satisfying
the proposed nonlinear boundary conditions. 相似文献
19.
Hossein Motavalli Amin Rezaei Akbarieh 《International Journal of Theoretical Physics》2010,49(5):979-987
In this paper we present the exact solutions of the one-dimensional Klein-Gordon equation for the Scarf-type potential with
equal scalar and vector potentials. Exact solutions and corresponding energy eigenvalues equation are obtained using Nikiforov-Uvarov
mathematical method for the s-wave bound state. The PT-symmetry and Hermiticity for this potential are also considered. It
will be shown that the obtained results of the Scarf-type potential are reduced to the results of the well-known potentials
in the special cases. 相似文献
20.
A prototype of a device with an impact structure for measuring the floor tilt has been built in our laboratory. The mechanical construction and the capacitive transducer of the device are introduced. Experimental results indicate that the floor tilt is about 16#tad in our cavity laboratory, and the uncertainty AG/G caused by such tilt is less than 0.54 parts per million (ppm), so the floor tilt can be reasonably neglected in the experimental determination of the gravitational constant G with the total uncertainty of about l0ppm. 相似文献