Coarse-Grained Picture for Controlling Complex Quantum Systems

We propose a coarse-grained picture to control ``complex'' quantum dynamics, i.e., multi-level-multi-level transition with a random interaction. Assuming that optimally controlled dynamics can be described as a Rabi-like oscillation between an initial and final state, we derive an analytic optimal field as a solution to optimal control theory. For random matrix systems, we numerically confirm that the analytic optimal field steers an initial state to a target state which both contains many eigenstates.Comment: jpsj2.cls, 2 pages, 3 figure files; appear in J. Phys. Soc. Jpn. Vol.73, No.11 (Nov. 15, 2004

Investigation of ultrafast laser photonic material interactions: challenges for directly written glass photonics

Currently, direct-write waveguide fabrication is probably the most widely studied application of femtosecond laser micromachining in transparent dielectrics. Devices such as buried waveguides, power splitters, couplers, gratings and optical amplifiers have all been demonstrated. Waveguide properties depend critically on the sample material properties and writing laser characteristics. In this paper we discuss the challenges facing researchers using the femtosecond laser direct-write technique with specific emphasis being placed on the suitability of fused silica and phosphate glass as device hosts for different applications.Comment: 11 pages, 87 references, 11 figures. Article in revie

In-situ measurement and the reconstruction in 3D of femtosecond inscription induced complex permittivity modification in glass

We demonstrate a new approach to in-situ measurement of femtosecond laser pulse induced changes in glass enabling the reconstruction in 3D of the induced complex permittivity modification. The technique can be used to provide single shot and time resolved quantitative measurements with a micron scale spatial resolution

Positron Lifetime Spectroscopy of Silicon Nanocontainers for Cancer Theranostic Applications

Biocompatibility and biodegradability of porous silicon (por-Si) nanoparticles (NPs), as well as the fact that they can selectively accumulate in tumor tissues, allow using them as containers for delivery of diagnostic markers or drugs for therapy of cancer tumors. Advantages of por-Si NPs as carriers of drugs are also favorable due to the high surface area and large pore volume. To apply por-Si NPs as nanocontainers it is necessary to have the comprehensive information about their porosity. In our work we use the positron annihilation lifetime (PAL) spectroscopy for porosity investigation. Samples of por-Si were prepared by electrochemical etching of heavily boron doped crystalline Si wafers in a hydrofluoric acid solution. The prepared por-Si films were dried and mechanically milled to obtain powder of NPs, which was pressed into tablets for PAL investigation. Ortho-positronium components of the measured positron lifetime spectra allowed us to evaluate the pore size distribution in por-Si NPs as continuous bimodal one with two peaks near 1 nm and 3 nm. Keywords: positron annihilation lifetime spectroscopy, positronium, porous silicon nanoparticles, nanocontainers, porosimetry, theranostics