A rough hydrophobic surface when immersed in water can result in a "Cassie" state of wetting in which the water is in contact with both the solid surface and the entrapped air. The sustainability of the entrapped air on such surfaces is important for underwater applications such as reduction of flow resistance in microchannels and drag reduction of submerged bodies such as hydrofoils. We utilize an optical technique based on total internal reflection of light at the water-air interface to quantify the spatial distribution of trapped air on such a surface and its variation with immersion time. With this technique, we evaluate the sustainability of the Cassie state on hydrophobic surfaces with four different kinds of textures. The textures studied are regular arrays of pillars, ridges, and holes that were created in silicon by a wet etching technique, and also a texture of random craters that was obtained through electrodischarge machining of aluminum. These surfaces were rendered hydrophobic with a self-assembled layer of fluorooctyl trichlorosilane. Depending on the texture, the size and shape of the trapped air pockets were found to vary. However, irrespective of the texture, both the size and the number of air pockets were found to decrease with time gradually and eventually disappear, suggesting that the sustainability of the "Cassie" state is finite for all the microstructures studied. This is possibly due to diffusion of air from the trapped air pockets into the water. The time scale for disappearance of air pockets was found to depend on the kind of microstructure and the hydrostatic pressure at the water-air interface. For the surface with a regular array of pillars, the air pockets were found to be in the form of a thin layer perched on top of the pillars with a large lateral extent compared to the spacing between pillars. For other surfaces studied, the air pockets are smaller and are of the same order as the characteristic length scale of the texture. Measurements for the surface with holes indicate that the time for air-pocket disappearance reduces as the hydrostatic pressure is increased.

Theoretical Quantum Information Processing (QIP) has matured from the use of qubits to the use of qudits (systems having states > 2). Where as most of the experimental implementations have been performed using qubits, little experimental work has been carried out using qudits as yet.In this paper we demonstrate experimental realization of a qutrit system by nuclear magnetic resonance (NMR), utilizing deuterium (spin-1) nuclei partially oriented in liquid crystalline phase.Preparation of pseudopure states and implementation of unitary operations are demonstrated in this single-qutrit system, using transition selective pulses. I. INTRODUCTIONA future quantum computer has the advantage of simulating physical systems and solving certain problems more efficiently than classical computers [1][2][3][4][5]. Classical computer use bits as basic units of information whereas quantum computers use qubits (two-level systems) as basic units of information.Unlike bits, qubits can exist in coherent superposition of the two basic states |0 and |1 . Moreover quantum-mechanical systems can be 'entangled'. Entanglement is purely a quantum-mechanical property which has no classical analogue. Two quantum systems when entangled show non-local correlations which cannot be defined by classical statistical predictions. However, such quantum mechanical behavior is restricted not only to qubits but exists in all higher dimensional systems called qudits [6,7]. The degree of non-local correlations are in fact greater in case of entangled qutrits (three-level systems) than entangled qubits [8]. Several cryptographic protocols have been devised using qutrits which are argued to be highly secure against symmetric attacks [9][10][11]. Recently it has also been demonstrated that qutrits can be useful for certain purposes of quantum simulation [12], quantum computations [13][14][15] and quantum communication [16][17][18][19]. Among the various physical systems on which quantum simulations and algorithms have been experimentally realized, nuclear magnetic resonance (NMR) has proved to be the most successful to date [20][21][22][23][24][25][26]. In most of the

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CdS nanofilms of varying thickness (t) deposited by chemical bath deposition technique have been studied for structural changes using x-ray diffractometer (XRD) and transmission electron microscope (TEM). XRD analysis shows polycrystalline nature in deposited films with preferred orientation along (002) reflection plane also confirmed by selected area diffraction pattern of TEM. Uniform and smooth surface morphology observed using field emission scanning electron microscope. The surface topography has been studied using atomic force microscope. The optical constants have been calculated from the analysis of %T and %R spectra in the wavelength range 300 nm-900 nm. CdS nanofilms show a direct transition with red shift. The optical band gap decreases while the refractive index increases with increase in thickness of nanofilms.

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Slippery liquid-infused porous surfaces (SLIPSs) have been explored for many applications, taking advantage of their highly non-wetting property. In this work, we explore the SLIPS as a cladding material for waveguiding. SLIPSs are prepared by infusing perfluoropolyether oil to hydrophobized nanoporous surfaces of silicon. Power loss and transmission efficiency of an HeNe laser (1.82 mW and 632.8 nm) with varying incident angles were measured through microchannels consisting of the SLIPSs as cladding layers (noil = 1.30) and water (nwater = 1.33) as a core, compared to other cladding types including a planar silicon surface and the nanoporous surfaces in hydrophilic (Wenzel state) and hydrophobic (Cassie–Baxter state) conditions with no oil infused. Agreeing with Snell's law, a total internal reflection occurs at the incident angle as high as 14° for the SLIPSs. The waveguide loss at 14° is only 1.8 dB/cm for the SLIPSs, while those for planar silicon, hydrophilic nanoporous, and hydrophobic nanoporous surfaces are 5.9, 7.4, and 4.9 dB/cm, respectively. The power transmission efficiency of the SLIPSs is independent of the porosity because the surfaces are fully covered with the oil layer, whereas those of hydrophilic and hydrophobic nanoporous surfaces, whose pores are filled with water and air, respectively, depend on the porosity. The significantly lower power loss and the insensitivity to the surface porosity are advantages of the SLIPSs over the other surfaces and can benefit in waveguiding applications such as optofluidics.