[en] We describe recent and ongoing studies at the National High Magnetic Field Laboratory at Los Alamos using the new '100 Tesla Multi-Shot Magnet', which is presently delivering fields up to ∼89 T during its commissioning. We discuss the first experiments performed in this magnet system, wherein the linewidth of low-temperature photoluminescence spectra was used to directly reveal the degree of magnetic alloy disorder 'seen' by excitons in single Zn_0.80Cd_0.22Mn_0.08Se quantum wells. The magnetic potential landscape in II-VI diluted magnetic semiconductors (DMS) is typically smoothed when the embedded Mn²⁺ spins align in an applied field. However, an important (but heretofore untested) prediction of current models of compositional disorder is that magnetic alloy fluctuations in many DMS compounds should increase again in very large magnetic fields approaching 100 T. We observed precisely this increase above ∼70 T, in agreement with a simple model of magnetic alloy disorder.

[en] A strong temperature dependent phenomenon of the Josephson plasma resonance mode has been found in high-Tc superconductor Bi₂Sr₂CaCu₂O_8+δ in a microwave frequency region between 9 and 50 GHz. The longitudinal plasma frequency sharply decreases and disappears just below Tc. The extrapolated plasma energy is estimated to be bar hω_p(0) = 2.59 x 10^-4 eV. Since the plasma frequency, ω_p, is determined by the Anderson-Higgs-Kibble mechanism and it is expected to be temperature independent, this phenomenon can not be accounted for by the conventional understanding of the plasma mode in superconductors. Experimental results are discussed in terms of the two fluid model, in which the intrinsic Josephson nature of the coupling restricting the tunneling probability of quasiparticles between layers is considered to be as a dumping mechanism of the quasi-particles in this system

[en] The nonperturbative response of atomic systems under strong laser radiation has been an important area of research both experimentally and theoretically. In a typical experiment, a very high power laser (operating at an intensity of the order of 10¹³ W/cm² or higher, delivering 1μm wavelength light pulses with duration from a few pico-seconds down to a few hundred femto-seconds) is focused down to a tight spot in space filled with dilute gas where ionization occurs. These experiments have been successful in studying the single-atom strong-field physics where the prediction of ionization based on low-field perturbation theory are invalid. Various theories have been used to explain new effects associated with different intensity regions. In this review the authors intend to summarize the steps for arriving at a new theoretical prediction of atoms in laser pulses of intensity 10¹⁶ W/cm² or stronger. The prediction that atoms tend to stabilize in laser pulses strong enough to produce full ionization is rather counter-intuitive. The phenomenon of atomic stabilization will be introduced through space-time integration of Schroedinger equation. A more quantitative account of the associated effects during a stabilization will be analyzed through a simplified one-dimensional long-range potential. To further understand the features of stabilization, a one-dimensional short-range potential is also employed. They will mention some possible experimental consequences of stabilization

[en] This is a review of recent work on the dynamic response of Josephson junction arrays driven by dc and ac currents. The arrays are modeled by the resistively shunted Josephson junction model, appropriate for proximity effect junctions, including self-induced magnetic fields as well as disorder. The relevance of the self-induced fields is measured as a function of a parameter κ = λ_L/a, with λ_L the London penetration depth of the arrays, and a the lattice spacing. The transition from Type II (κ > 1) to Type I (κ < 1) behavior is studied in detail. The authors compare the results for models with self, self + nearest-neighbor, and full inductance matrices. In the κ = ∞ limit, they find that when the initial state has at least one vortex-antivortex pair, after a characteristic transient time these vortices unbind and radiate other vortices. These radiated vortices settle into a parity-broken, time-periodic, axisymmetric coherent vortex state (ACVS), characterized by alternate rows of positive and negative vortices lying along a tilted axis. The ACVS produces subharmonic steps in the current voltage (IV) characteristics, typical of giant Shapiro steps. For finite κ they find that the IV's show subharmonic giant Shapiro steps, even at zero external magnetic field. They find that these subharmonic steps are produced by a whole family of coherent vortex oscillating patterns, with their structure changing as a function of κ. In general, they find that these patterns are due to a breakdown of translational invariance produced, for example, by disorder of antisymmetric edge-fields. The zero field case results are in good qualitative agreement with experiments in Nb-Au-Nb arrays

[en] Raman scattering in high-temperature superconductors is considered, assuming the presence of a random potential caused by either crystal non-stoichiometry or oxygen disorder. The renormalization of the electron-phonon interaction by impurity scattering for phonons of different symmetry has been analyzed. The analysis has been extended o as to take into consideration the finite wave vector phonons. On the basis of the theory developed, unusual properties of phonon Raman scattering in the high-temperature superconductors are qualitatively considered. They include the phonon line-shape and its dependence on the scattering polarizations and resonant conditions, and non-Bose temperature dependence of a number of Raman active phonons

[en] The progress in solving the x-ray phase problem by multiple diffraction method is reviewed in this paper. The theoretical and experimental aspects of this diffraction method are outlined. Recent experimental findings and theoretical development in phasing the structure-factors are described as well. The future trend of this particular research is also tentatively outlooked

[en] This paper reports on map coloring, q-deformed spin networks, and Turaev-viro m variants for 3-manifolds. Also discussed are errors, correction, m variance principle and equations

[en] In this paper, the quantum mechanics of a particle moving on a pseudosphere under the action of a constant magnetic field is studied from an algebraic point of view. The magnetic group on the pseudosphere is SU(1,1). The Hilbert space for the discrete part of the spectrum is investigated. The eigenstates of the non-compact operators (the hyperbolic magnetic translators) are constructed and shown to be expressible as continuous superpositions of coherent states. The planar limit of both the algebra and the eigenstates is analyzed. Some possible applications are briefly outlined

[en] In this paper, the authors study the squeezing and the quasiprobability distribution Q-function for an extended two-photon Jaynes-Cummings model (JCM) that includes atomic motion and the field mode structure. A comparative study of this model with respect to the standard model (in which the atom is at rest) has been presented here to isolate the effect of limited atom-radiation interaction time

[en] In this paper, amplitude-squared (AS) squeezing has been investigated for the m-photon Jaynes-Cummings model assuming the field to be initially in the squeezed states. The role played by intensity-dependent coupling has also been discussed. It has been shown that for the large initial average photon number (bar n) with odd values of m, AS squeezing revokes permanently whereas with even values it recurs periodically. As m increases the revocation is hastened and the duration of occurrence decreases. Higher values of m for the initial field in a squeezed vacuum state can make one of the quadrature permanently squeezed. The AS squeezing behavior for two initial states of the atom, i.e., ground state versus excited state is also compared