Bose-Einstein model

Table 3.5. Best-model parameters of the temperature-dependent phonon mode shift in Fig. 3.11b, calculated by (3.22) (Bose-Einstein model) [43]...

At higher temperatures the semiempirical Bose-Einstein model function can be applied [129,166]... 

Table 3.13. Parameters of the temperature dependence of Eq according to the Varshni and Bose-Einstein model for ZnO single crystal bulk samples...

In a simplistic and conservative picture the core of a neutron star is modeled as a uniform fluid of neutron rich nuclear matter in equilibrium with respect to the weak interaction (/3-stable nuclear matter). However, due to the large value of the stellar central density and to the rapid increase of the nucleon chemical potentials with density, hyperons (A, E, E°, E+, E and E° particles) are expected to appear in the inner core of the star. Other exotic phases of hadronic matter such as a Bose-Einstein condensate of negative pion (7r ) or negative kaon (K ) could be present in the inner part of the star. 

BOSE-EINSTEIN CONDENSATION IN A BOSON-FERMION MODEL OF CUPRATES... 

Key words Superconductivity cuprates boson-fermion model Bose-Einstein condensation. 

Bose-Einstein Condensation in a Boson-Fermion Model of Cuprates 135 T.A. Mamedov, and M. de Llano... 

The important fact that the quantum theory explains the extraordinarily small specific heat of electrons at normal temperatures, as is well known, was pointed out by Sommerfeld. Our model likewise explains this fact, though in a somewhat different way. If, as is permissible here, we work with the spins in the same way as we previously did with the free electrons, it follows by what we have said above that we have to deal with a degenerate Bose-Einstein gas, the specific heat of which at low temperatures is, as we know, given by... 

An alternative approach is the Slave Boson approximation [21] where the Fermionic operators are defined as the product of Boson and spin operators. There is a constraint with the number of Fermions, n /, and number of Bosons, n n f - - m, = 1. The spin part is treated with a RVB spin model and the charge as a Bose-Einstein condensation problem. These leads to a fractionalization of charges (holons) and spin (spinons), where uncondensed holons exist above the SC domain. The temperature crossover of the spinon pairing and the holon condensation, as a function of doping, is identified as peak in the SC domain. 

Abstract Using our Bose-Einstein condensation (BEC) machine and the Bragg spectroscopy technique we study excitation evolution and decay in BEC. New results have been achieved with this system, and are reported here. We also develop various theoretical models for simulating atomic optical behavior in dynamically changing trapping schemes. 

In order to study the decoherence of quasi-particles within BEC, we use Bragg spectroscopy and Monte Carlo hydrodynamic simulations of the system [Castin 1996], and confirm recent theoretical predictions of the identical particle collision cross-section within a Bose-Einstein condensate. We use computerized tomography [Ozeri 2002] of the experimental images in determining the exact distributions. We then conduct both quantum mechanical and hydrodynamic simulation of the expansion dynamics, to model the distribution of the atoms, and compare theory and experiment [Katz 2002] (see Fig. 2). 

Because the first models of the physics of superconductivity were based on the phenomenon of Bose-Einstein condensation (BEC) it is not surprising that the existence of the Josephson effect has also been postulated for cold-atom systems in the BEC state [11]. In both superconductors and BEC cold-atom systems, the Josephson effect arises from the approximation of non-conservation of particle number, which gives rise to a phase type of order parameter F(x) and concomitant wave phenomena, described at T = 0 by the Gross-Pitaevski equation " ... 

Figure 4. The bridging between Bose-Einstein condensation in the low-density, weak interaction region and in the high-density, strong interaction region [124, 125]. Data for Tc/r , where is the critical temperature and T is the critical temperature in an ideal Bose-Einstein gas, were calculated from quantum path integral Monte-Carlo simulations for a hard-sphere many-boson model [124, 125], The effective dimensionless interaction parameter is pa, where p is the density and CT is the hard-core sphere diameter. The two open circles (o) represent experimental data for bulk liquid He.

The dielectric spectrum (DS), pertaining to the T-band region, arises also in a certain specific form in the low-frequency Raman spectrum (RS). Comparison of both spectra allows us to improve the parameterization of our molecular model. Namely, in view of recent works (Gaiduk et al. [24], Gaiduk [25], we may write down the following relationships for the so-called R(v) and Bose-Einstein (BE) representations of the RS, denoted, respectively, Ir(v) and /hi (v) ... 

The prediction of the existence of a phenomenon analogous to a Bose-Einstein condensation, as in Frohlich s vibrational model, has been confirmed via several other approaches, namely, via a transport theory formalism by Kaiser and a molecular Hamiltonian approach by Bhaumik et and also by Wu and Austinthe basic concept has been shown to be on firm theoretical ground. The difficulty in these ideas gaining wide acceptance is the lack of conclusive experimental evidence to provide confirmation that such effects occur in biological membranes. Furthermore, the theory presented thus far is not at the stage where it can be used in an analytical sense to explain those data thus far reported or be used in a predictive manner. 

The Bose-Einstein distribution (1.162) may be considered to recover the Planck law of black body radiation, i.e., the photon radiation modeling, by considering the following peculiarities ... 

---