In this Letter, we report on the densest-known packings of congruent ellipsoids. The family of new packings consists of crystal arrangements of spheroids with a wide range of aspect ratios, and with density φ always ...
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In this Letter, we report on the densest-known packings of congruent ellipsoids. The family of new packings consists of crystal arrangements of spheroids with a wide range of aspect ratios, and with density φ always surpassing that of the densest Bravais lattice packing φ≈0.7405. A remarkable maximum density of ϕ≈0.7707 is achieved for maximal aspect ratios larger than 3, when each ellipsoid has 14 touching neighbors. Our results are directly relevant to understanding the equilibrium behavior of systems of hard ellipsoids, and, in particular, the solid and glassy phases.
Calculated polar magneto-optic Kerr rotation and ellipticity angles are presented for the system Cu4Ni8CunNi9∕Cu(100), n=2,…,10. Contrary to the common belief, the Kerr signals are found to be not directly proportio...
Calculated polar magneto-optic Kerr rotation and ellipticity angles are presented for the system Cu4Ni8CunNi9∕Cu(100), n=2,…,10. Contrary to the common belief, the Kerr signals are found to be not directly proportional to the total magnetic moment. It will be shown that in order to assign at least indirectly the size (and sign) of the Kerr angles and therefore the type of coupling to a kind of total magnetic moment, one has to consider weighted layer-resolved moments, e.g., weighted by the damping factors of the reflected waves. As to be expected the occurring oscillations in the Kerr angles with respect to the spacer thickness resemble closely those for the interlayer exchange coupling energy.
By employing a real-space formulation of the Kubo-Greenwood equation based on a Green’s function embedding technique combined with the fully relativistic spin-polarized Korringa-Kohn-Rostoker method a detailed invest...
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By employing a real-space formulation of the Kubo-Greenwood equation based on a Green’s function embedding technique combined with the fully relativistic spin-polarized Korringa-Kohn-Rostoker method a detailed investigation of the electrical transport through atomic-scaled contacts between two Au(001) semi-infinite systems is presented. Following a careful numerical test of the method the conductance of Au nanocontacts with different geometries is calculated and, in turn, correlated with the thickness of the constriction. Particular emphasis is paid to the influence of transition metal impurities (Pd, Fe, and Co) placed on various positions near the center of a particular contact. We found that the conductance is very sensitive to the position of the magnetic impurities and that the mechanism for the occurring relative changes can mainly be attributed to the impurities’ minority d-band inducing resonant line shapes in the s-like density of states at the center of the contact.
We investigate the possibility of quantum (or wave) chaos for the Bogoliubov excitations of a Bose-Einstein condensate in billiards. Because of the mean field interaction in the condensate, the Bogoliubov excitations ...
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We investigate the possibility of quantum (or wave) chaos for the Bogoliubov excitations of a Bose-Einstein condensate in billiards. Because of the mean field interaction in the condensate, the Bogoliubov excitations are very different from the single particle excitations in a noninteracting system. Nevertheless, we predict that the statistical distribution of level spacings is unchanged by mapping the non-Hermitian Bogoliubov operator to a real symmetric matrix. We numerically test our prediction by using a phase shift method for calculating the excitation energies.
O’Hern, Silbert, Liu, and Nagel [Phys. Rev. E. 68, 011306 (2003)] claim that a special point J of a “jamming phase diagram” (in density, temperature, stress space) is related to random close packing of hard spheres...
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O’Hern, Silbert, Liu, and Nagel [Phys. Rev. E. 68, 011306 (2003)] claim that a special point J of a “jamming phase diagram” (in density, temperature, stress space) is related to random close packing of hard spheres and that it represents, for their suggested definitions of jammed and random, the recently introduced maximally random jammed state. We point out several difficulties with their definitions and question some of their claims. Furthermore, we discuss the connections between their algorithm and other hard-sphere packing algorithms in the literature.
A periodically kicked ring of a Bose-Einstein condensate is considered as a nonlinear generalization of the quantum kicked rotor. For weak interactions between atoms, periodic motion (antiresonance) becomes quasiperio...
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A periodically kicked ring of a Bose-Einstein condensate is considered as a nonlinear generalization of the quantum kicked rotor. For weak interactions between atoms, periodic motion (antiresonance) becomes quasiperiodic (quantum beating) but remains stable. There exists a critical strength of interactions beyond which quasiperiodic motion becomes chaotic, resulting in an instability of the condensate manifested by exponential growth in the number of noncondensed atoms. Similar behavior is observed for dynamically localized states (essentially quasiperiodic motions), where stability remains for weak interactions but is destroyed by strong interactions.
A simplified set of equations is derived systematically below for the interaction of large scale flow fields and precipitation in the tropical atmosphere. These equations, the Tropical Climate Model, have the form of ...
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Strong terahertz (1THz=1012Hz) radiation can be generated by the electron oscillation in fs-laser-induced wake fields. The interaction of a fs-laser pulse with a low-density plasma layer is studied in detail using num...
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Strong terahertz (1THz=1012Hz) radiation can be generated by the electron oscillation in fs-laser-induced wake fields. The interaction of a fs-laser pulse with a low-density plasma layer is studied in detail using numerical simulations. The spatial distribution and temporal evolution of terahertz electron current developed in a low-density plasma layer are presented, which enables us to calculate the intensity distribution of THz radiation. It is shown that laser and plasma parameters, such as laser intensity, pulse width, and background plasma density, are of key importance to the process. The optimum condition for wake-field excitation and terahertz emission is discussed upon the simulation results. Radiation peaked at 6.4 THz, with 900 fs duration and 9% bandwidth, can be generated in a plasma of density 5×1017cm−3. It turns out that the maximum radiation intensity scales as n03a04 when wake field is resonantly excited, where n0 and a0 are, respectively, the plasma density and the normalized field amplitude of the laser pulse.
Clauser-Horne-Shimony-Holt inequality for bipartite systems of four dimensions is studied in detail by employing the unbiased eight-port beam splitters measurements. The uniform formulas for the maximum and minimum va...
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Clauser-Horne-Shimony-Holt inequality for bipartite systems of four dimensions is studied in detail by employing the unbiased eight-port beam splitters measurements. The uniform formulas for the maximum and minimum values of this inequality for such measurements are obtained. Based on these formulas, we show that an optimal nonmaximally entangled state is about 6% more resistant to noise than the maximally entangled one. We also give the optimal state and the optimal angles which are important for experimental realization.
We present a theorem that all generalized Greenberger-Horne-Zeilinger states of a three-qubit system violate a Bell inequality in terms of probabilities. All pure entangled states of a three-qubit system are shown to ...
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We present a theorem that all generalized Greenberger-Horne-Zeilinger states of a three-qubit system violate a Bell inequality in terms of probabilities. All pure entangled states of a three-qubit system are shown to violate a Bell inequality for probabilities; thus, one has Gisin’s theorem for three qubits.
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