凝聚态物理
We observe the dynamic formation of $Cs_2$ molecules near Feshbach resonances in a cold sample of atomic cesium using an external probe beam. This method is 300 times more sensitive than previous atomic collision rate methods, and allows us…
Typical properties of glassy materials are shown to be captured by a mean-field free-volume theory. Relaxation processes are supposed to be free-volume activated, and different entropy barriers are associated with density relaxation and…
We present a theory for the laboratory and epidemiological data for incubation times in infectious prion diseases. The central feature of our model is that slow growth of misfolded protein-aggregates from small initial seeds controls the…
We study the resistivity vs. electric field dependence $\rho(E)$ of a 2D hole system in SiGe close to the B=0 metal-insulator transition. Using $\rho$ as a ``thermometer'' to obtain the effective temperature of the holes $T_e(E)$, we find…
Macroscopic quantum coherence of Bose gas in a double-well potential is studied based on SU(2)-coherent-state path-integral. The ground state and fluctuations around it can be obtained by this method. In this picture, one can obtain…
We study the rheology of a granular material slowly driven in a confined geometry. The motion is characterized by a steady sliding with a resistance force increasing with the driving velocity and the surrounding relative humidity. For lower…
Electrostatic force microscopy at cryogenic temperatures was used to probe the electrostatic interaction between a conductive atomic force microscopy tip and electronic charges trapped in an InAs quantum dot. Measurement of the…
Quasicrystals are metal alloys whose noncrystallographic symmetry and lack of structural periodicity challenge methods of experimental structure determination. Here we employ quantum-based total-energy calculations to predict the structure…
We study the spectral width as a function of the external momentum for the dynamical structure factor of a disordered harmonic solid, considered as a toy model for supercooled liquids and glasses. Both in the context of single-link coherent…
An approximate method to calculate dielectric response and relaxation functions for water saturated sedimentary rocks is tested for realistic threedimensional pore space images. The test is performed by comparing the prediction from the…
We present some aspects of the rheology of field-responsive suspensions, a class of field-responsive liquid matter systems possessing the ability to undergo significant changes in their strength upon application of an external field. Both…
Stimulated small-angle light scattering was used to measure the structure factor of a Bose-Einstein condensate in the phonon regime. The excitation strength for phonons was found to be significantly reduced from that of free particles,…
The effect of strong laser radiation on magnetic subbands in semiconductor superlattices is investigated. Due to the presence of a magnetic field perpendicular to the growth direction, non-linear effects such as band supression and electron…
All the new layer perovskite superconductors seem to show a phenomenon of symmetry mixing with repect to the order parameter. An analysis of the different alternative of mixing and how far could them be presented is carried out. For the…
We examine the paper basic equations of T. Doma\'nski and K.I. Wysoki\'nski [Phys. Rev. B {\bf 59}, 173 (1999)], who calculated the critical superconducting temperature, T_c, in function of Coulomb correlations (U) for s- and d-wave order…
We investigate groundstate energies and magnetization curves in the one dimensional XXZ-model with next to nearest neighbour coupling $\alpha>0$ and anisotropy $\Delta$ ($-1 \le \Delta \le 1$) at T=0. In between the familiar ferro- and…
We evaluate the one-particle and double-occupied Green functions for the Hubbard model at half-filling using the moment approach of Nolting. Our starting point is a self-energy, $\Sigma(\vec{k},\omega)$, which has a single pole,…
A new type of Langevin equation exhibiting a non trivial phase transition associated with the presence of multiplicative noise is introduced. The equation is derived as a mesoscopic representation of the microscopic annealed Ising model…
A new strongly correlated electron model is presented. This is formed by two types of sites: one where double occupancy is forbidden, as in the t-J model, and the other where double occupancy is allowed but vacancy is not allowed, as an…
The associated Hamiltonian for a su(3) spin chain combining ${3}$ and ${3^{*}}$ representations is calculated. The ansatz equations for this chain are obtained and solved in the thermodynamic limit, and the ground state and excitations are…