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K. Sugiyama

Publications and source records attributed to K. Sugiyama.

32 records · Page 2Linked to original sources
arXiv2009

Direct observation of geometric phases using a three-pinhole interferometer

We present a method to measure the geometric phase defined for three internal states of a photon (polarizations) using a three-pinhole interferometer. From the interferogram, we can extract the geometric phase related to the three-vertex Bargmann invariant as the area of a triangle formed by interference fringes. Unlike the conventional methods, our method does not involve the state evolution. Moreover, the phase calibration of the interferometer and the elimination of the dynamical phase are not required. The gauge invariance of the geometric phase corresponds to the fact that the area of the triangle is never changed by the local phase shift in each internal state.

quant-ph↗
arXiv2008

Wetting failure and contact line dynamics in a Couette flow

Liquid-liquid wetting failure is investigated in a two-dimensional Couette system with two immiscible fluids of arbitrary viscosity. The problem is solved exactly using a sharp interface treatment of hydrodynamics (lubrication theory) as a function of the capillary number, viscous ratio and separation of scale, i.e. slip length versus macroscopic scale of the system. The existence of critical velocities, above which no stationary solutions are found, is analyzed in detail in terms of the relevant parameters of the system. Comparisons with existing analysis for other geometries are also carried out. A numerical method of analysis is also presented, based on diffuse interface models obtained from multiphase extensions of the lattice Boltzmann equation (LBE). Sharp interface and diffuse interface models are quantitatively compared face to face indicating the correct limit of applicability of the diffuse interface models.

physics.flu-dyn↗
arXiv2008

An invisible medium for circularly polarized electromagnetic waves

We study the no reflection condition for a planar boundary between vacuum and an isotropic chiral medium. In general chiral media, elliptically polarized waves incident at a particular angle satisfy the no reflection condition. When the wave impedance and wavenumber of the chiral medium are equal to the corresponding parameters of vacuum, one of the circularly polarized waves is transmitted to the medium without reflection or refraction for all angles of incidence. We propose a circular polarizing beam splitter as a simple application of the no reflection effect.

physics.optics↗
arXiv2007

Linear shear flow past a hemispherical droplet adhering to a solid surface

This paper investigates the properties of a three dimensional shear flow overpassing a hemispherical droplet resting on a plane wall. The exact solution is computed as a function of the viscosity ratio between the droplet and the surrounding fluid and generalizes the solution for the hemispherical no-slip bump given in an earlier paper by Price (1985). Several expressions including the torque and the force acting on the drop will be considered as well as the importance of the deformations on the surface for small Capillary numbers.

cond-mat.soft↗
arXiv2006

Generalized Lattice Boltzmann Method with multi-range pseudo-potential

The physical behaviour of a class of mesoscopic models for multiphase flows is analyzed in details near interfaces. In particular, an extended pseudo-potential method is developed, which permits to tune the equation of state and surface tension independently of each other. The spurious velocity contributions of this extended model are shown to vanish in the limit of high grid refinement and/or high order isotropy. Higher order schemes to implement self-consistent forcings are rigorously computed for 2d and 3d models. The extended scenario developed in this work clarifies the theoretical foundations of the Shan-Chen methodology for the lattice Boltzmann method and enhances its applicability and flexibility to the simulation of multiphase flows to density ratios up to O(100).

nlin.CG↗
arXiv2006

Observation of Brewster's effect for transverse-electric electromagnetic waves in metamaterials: Experiment and theory

We have experimentally realized Brewster's effect for transverse-electric waves with metamaterials. In dielectric media, Brewster's no-reflection effect arises only for transverse-magnetic waves. However, it has been theoretically predicted that Brewster's effect arises for TE waves under the condition that the relative permeability r is not equal to unity. We have designed an array of split-ring resonators as a metamaterial with mu_r 1 using a finite-difference time-domain method. The reflection measurements were carried out in a 3-GHz region and the disappearance of reflected waves at a particular incident angle was confirmed.

physics.optics↗
arXiv2006

Boundary induced non linearities at small Reynolds Numbers

We investigate the influence of boundary slip velocity in Newtonian fluids at finite Reynolds numbers. Numerical simulations with Lattice Boltzmann method (LBM) and Finite Differences method (FDM) are performed to quantify the effect of heterogeneous boundary conditions on the integral and local properties of the flow. Non linear effects are induced by the non homogeneity of the boundary condition and change the symmetry properties of the flow inducing an overall mean flow reduction. To explain the observed drag modification, reciprocal relations for stationary ensembles are used, predicting a reduction of the mean flow rate from the creeping flow to be proportional to the fourth power of the friction Reynolds number. Both numerical schemes are then validated within the theoretical predictions and reveal a pronounced numerical efficiency of the LBM with respect to FDM.

cond-mat.other↗
arXiv2004

Influence of intermartensitic transitions on transport properties of Ni2.16Mn0.84Ga alloy

Magnetic, transport, and x-ray diffraction measurements of ferromagnetic shape memory alloy Ni$_{2.16}$Mn$_{0.84}$Ga revealed that this alloy undergoes an intermartensitic transition upon cooling, whereas no such a transition is observed upon subsequent heating. The difference in the modulation of the martensite forming upon cooling from the high-temperature austenitic state [5-layered (5M) martensite], and the martensite forming upon the intermartensitic transition [7-layered (7M) martensite] strongly affects the magnetic and transport properties of the alloy and results in a large thermal hysteresis of the resistivity $ρ$ and magnetization $M$. The intermartensitic transition has an especially marked influence on the transport properties, as is evident from a large difference in the resistivity of the 5M and 7M martensite, $(ρ_{\mathrm{5M}} - ρ_{\mathrm{7M}})/ρ_{\mathrm{5M}} \approx 15%$, which is larger than the jump of resistivity at the martensitic transition from the cubic austenitic phase to the monoclinic 5M martensitic phase. We assume that this significant difference in $ρ$ between the martensitic phases is accounted for by nesting features of the Fermi surface. It is also suggested that the nesting hypothesis can explain the uncommon behavior of the resistivity at the martensitic transition, observed in stoichiometric and near-stoichiometric Ni-Mn-Ga alloys.

cond-mat.mtrl-sci↗
arXiv2003

Negative Group Delay and Superluminal Propagation: An Electronic Circuit Approach

We present a simple electronic circuit which provides negative group delays for band-limited, base-band pulses. It is shown that large time advancement comparable to the pulse width can be achieved with appropriate cascading of negative-delay circuits but eventually the out-of-band gain limits the number of cascading. The relations to superluminality and causality are also discussed.

quant-ph↗
arXiv2003

Generation of photon pairs using polarization-dependent two-photon absorption

We propose a new method for generating photon pairs from coherent light using polarization-dependent two-photon absorption. We study the photon statistics of two orthogonally polarized modes by solving a master equation, and show that when we prepare a coherent state in one polarization mode, photon pairs are created in the other mode. The photon pairs have the same frequency as that of the incident light.

quant-ph↗
arXiv2002

Demonstration of negative group delays in a simple electronic circuit

We present a simple electronic circuit which produces negative group delays for base-band pulses. When a band-limited pulse is applied as the input, a forwarded pulse appears at the output. The negative group delays in lumped systems share the same mechanism with the superluminal light propagation, which is recently demonstrated in an absorption-free, anomalous dispersive medium [Wang et al., Nature 406, 277 (2000)]. In this circuit, the advance time more than twenty percent of the pulse width can easily be achieved. The time constants, which can be in the order of seconds, is slow enough to be observed with the naked eye by looking at the lamps driven by the pulses.

quant-ph↗
arXiv1999

AdS_3/CFT_2 Correspondence and Space-Time N=3 Superconformal Algebra

We study a Wess-Zumino-Witten model with target space AdS_3 x (S^3 x S^3 x S^1)/Z_2. This allows us to construct space-time N=3 superconformal theories. By combining left-, and right-moving parts through a GSO and a Z_2 projections, a new asymmetric (N,\bar{N})=(3,1) model is obtained. It has an extra gauge (affine) SU(2) symmetry in the target space of the type IIA string. An associated configuration is realized as slantwise intersecting M5-M2 branes with a Z_2-fixed plane in the M-theory viewpoint.

hep-th↗
arXiv1996

BPS mass spectrum from D-brane action

We derive the BPS mass formulae of the Dirichlet branes from the Born-Infeld type action. BPS saturation is realized when the brane has the minimal volume while keeping the appropriate winding numbers. We apply the idea to two cases, type IIA superstring compactified on $T^4$ and $K3$. The result is consistent with the string duality, and the expected spectrum for the BPS states is reproduced.

hep-th↗