Noncontact measurement of liquid-surface properties with knife-edge electric field tweezers technique.

We have developed a technique for the simultaneous measurement of the surface tension and the viscosity of a liquid in a noncontact manner. In this method, a small linear deformation of the liquid surface is induced by a local dielectric force that is brought about by a knife-edge electrode. The surface tension and the viscosity are obtained from the shape of the induced meniscus and from the dynamic response of the surface, respectively. The surface tension obtained was examined in comparison with the values measured by the Wilhelmy plate method. We also measured time constants of the surface deformation for a variety of standard viscosity samples and obtained the relation between the time constant and the viscosity. The demonstrated advantage of the system is the ability to uniquely determine the surface tension and the viscosity.

Measurement of the skin layer in the drying process of a polymer solution.

When a polymer solution is dried in air, a polymer-concentrated region, called a "skin" layer, often appears near the surface. In this paper, an experimental method is proposed for detecting the initial process of the formation of the skin layer. An electric field is applied on the surface of polymer solutions by a wedge-type "electric field tweezers," and the dynamic response of the surface profile is measured by an optical lever technique. Our experiments and theory indicate that when a skin layer is formed, (i) the slow relaxation process appears in the time domain and (ii) the long-persisting dip region appears in the surface profile. A parameter to quantify the difference of the surface response is proposed in this paper.

Demonstration of unconditional one-way quantum computations for continuous variables.

One-way quantum computation is a very promising candidate to fulfill the capabilities of quantum information processing. Here we demonstrate an important set of unitary operations for continuous variables using a linear cluster state of four entangled optical modes. These operations are performed in a fully measurement-controlled and completely unconditional fashion. We implement three different levels of squeezing operations and a Fourier transformation, all of which are accessible by selecting the correct quadrature measurement angles of the homodyne detections. Though not sufficient, these linear transformations are necessary for universal quantum computation.