Marko V. Jarić

Soliton-like processes during right-left transition in DNA

Abstract A salt induced right-left conformational change in DNA is discussed. A phenomenological model is presented for the transition in short DNAs. For long DNAs. For long DNAs, a microscopic model equation of motion is analyzed. Solitary-waves solutions are demonstrated and some experimental implications are emphasized.

Exact solution to photorefractive two-wave mixing with arbitrary modulation depth

We obtain analytical solution to the slowly varying envelope wave equations describing two-wave mixing in photorefractive crystals with arbitrary dependence of the gain and absorption on the two-wave fringe modulation depth. We introduce a novel form of the correction function for the space charge field that offers an improved agreement with the experiment.

Structural phase transitions in crystals: Broken‐symmetry (isotropy) groups

A systematic procedure ensuring the determination of all isotropy groups of a given representation of a space group is presented for the first time. Isotropy groups play an important role in various areas of theoretical solid state physics. For example, only isotropy groups may occur in a structural phase transition driven by an order parameter belonging to a given representation. The method uses the chain criterion directly on the image of the representation, employing a labeling of the matrices by space group elements. A notion of a substar of a wave vector associated with the representation is central to the method. Finally, as a detailed illustration the method is applied to a structural phase transition in A15 systems driven by an X‐point order parameter. The result agrees with previously reported ones.

Optical photorefractive flip-flop oscillator

Abstract Using two interconnected four-wave mixing ring resonators with two photorefractive crystals included as active and passive intracavity optical elements, we display the operation of an all-optical flip-flop oscillator.

Space groups and their isotropy subgroups

The theory of space groups and their subgroups is related to that of their irreducible representations. Several important theorems concerning the determination of isotropy subgroups are proved. In particular, we show that the translation subgroups of isotropy subgroups are in one‐to‐one correspondence with certain subsets, called ‘‘substars,’’ of the ‘‘star’’ characterizing the irreducible representation of the space group.

Orbit space and minima of Landau–Higgs potentials

We establish a connection between recent propositions for minimization of Higgs potentials in an orbit space and related treatments in the Landau theory of phase transitions. Starting from isotropy groups we give a simple and systematic procedure for determining a stratification in an orbit space. As an illustration we treat the point groups Oh and Td which occur in the Higgs mechanism for SO7 and SU4 adjoint representations.

SELF-DIFFUSION IN RANDOM-TILING QUASICRYSTALS

The first explicit realization of the conjecture that phason dynamics leads to self-diffusion in quasicrystals is presented for the icosahedral Ammann tilings. On short time scales, the transport is found to be subdiffusive with the exponent

Exact solution to four-wave mixing with complex couplings: reflection geometry

\beta\approx0.57(1)

On the reconstruction of i(AlCuLi) X-ray structure factors☆

, while on long time scales it is consistent with normal diffusion that is up to an order of magnitude larger than in the typical room temperature vacancy-assisted self-diffusion. No simple finite-size scaling is found, suggesting anomalous corrections to normal diffusion, or existence of at least two independent length scales.

Nonmaximality and phase transitions

An exact solution to photorefractive four-wave mixing equations with complex couplings in ref lection geometry is obtained. It is shown that the efficiency of the process of phase conjugation can be enhanced by introduction of a frequency shift between the pumps and the signal, similar to the case of transmission geometry. However, to obtain an improved agreement with experiment, the inclusion of transverse effects is found to be necessary.