Striped interference pattern

Transient grating spectroscopy is relatively easily handled compared with the transient absorption spectroscopy, and is often used to study carrier dynamics at semiconductor electrodes [32]. Figure 14 schematically shows the principle of transient grating spectroscopy. A femtosecond laser pulse for sample excitation is split into two beams, which are crossed again at the semiconductor surface to produce an optical striped interference pattern. The interference pattern produces a striped pattern of the densities of photo-generated electrons and holes near the semiconductor surface. The latter striped pattern gives rise to a striped pattern of optical refractive index near the semiconductor surface, which is monitored by measuring a diffraction pattern of a second probe laser... 

Probability maps typically exhibit striped wave-like interference patterns. It is easy to show why striped i atterns (i.e. patterns for which, at a given time step, the site probabilities alternate between low and high values), emerge for all systems with Sc > /2. Assume that (7j t) 0, At time t -f 1 we then have... 

Figure 3.15 Phase space representation of the states of the computational basis of two qubits (a) 00), (b) 01), (c) 110) and (d) 111). The states are well defined in position (horizontal axis) and undefined in momentum (vertical axis). Amplitudes vary from —0.125 (white) to +0.125 (black). Due to the periodic boundary conditions, an interference pattern appears as the black and white stripes.

When a beam of electrons goes through two closely spaced slits (a), an interference pattern is created, as if the electrons were waves. By contrast, a beam of particles passing through two slits (b) produces two smaller beams of particles. Notice that particle beams produce two bright stripes with darkness in between but waves produce the brightest strip directly in the center of the screen. 

On the other hand ARCHEOPS only scanned around a circle of constant elevation and then let the center of the circle move in right ascension as the Earth turned. This provides only a two way modulation. Since the sky itself is a two dimensional function, just about any time history of drifting baselines is consistent with some pattern on the sky. Thus ARCHEOPS is very vulnerable to striping. This can be seen in the last panel of Figure 2 of astro-ph/0310788 (Hamilton et al., 2003) which clearly shows correlated residuals aligned with the scan path. These stripes have a low enough amplitude to not interfere with measurements of the temperature-temperature angular power spectrum CjT, but they would ruin a measurement of the polarization power spectrum CfE. 

A chemical pattern with precise surface chemistry and well-defined lateral dimension is a necessary platform to further advance the understanding of the self-assembly of block copolymer on the chemical patterns as well as improve the self-assembly quality. Nealey and his group developed a technique to generate chemical prepattems based on a lithographically defined resist strucmre and subsequent plasma surface modification. For example, a well-defined chemical prepattem was accomplished by first grafting PS-r-PMMA bmshes to a silicon substrate, covering it with an EUV resist (PMMA), and then creating a stripe pattern in the photoresist by EUV interference... 

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