Results for "Hirotaka Terai"

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Nonclasscial interference between independent intrinsically pure single photons at telecom wavelengthMar 12 2013Jul 24 2013We demonstrate a Hong-Ou-Mandel interference between two independent, intrinsically pure, heralded single photons from spontaneous parametric down conversion (SPDC) at telecom wavelength. A visibility of $85.5\pm8.3%$ was achieved without using any bandpass ... More
Mach-Zehnder interferometer using frequency-domain beamsplitterMar 23 2017We demonstrated the first-order interference between coherent light at 1580 nm and 795 nm by using frequency-domain Mach-Zehnder interferometer (MZI). The MZI is implemented by two frequency-domain BSs based on a second-order nonlinear optical effect ... More
Detection-dependent six-photon NOON state interferenceJul 04 2016NOON state interference (NOON-SI) is a powerful tool to improve the phase sensing precision, and can play an important role in quantum sensing and quantum imaging. However, most of the previous NOON-SI experiments only investigated the center part of ... More
A low-noise frequency down-conversion to the telecommunication band for a quantum communication based on NV centers in diamondFeb 12 2014We demonstrate a low-noise frequency down-conversion of photons at 637 nm to the telecommunication band at 1587 nm by the difference frequency generation in a periodically-poled lithium niobate. An internal conversion efficiency of the converter is estimated ... More
High performance fiber-coupled NbTiN superconducting nanowire single photon detectors with Gifford-McMahon cryocoolerMar 26 2013Apr 11 2013We present high performance fiber-coupled niobium titanium nitride superconducting nanowire single photon detectors fabricated on thermally oxidized silicon substrates. The best device showed a system detection efficiency (DE) of 74%, dark count rate ... More
Uniqueness structure of weakly coupled systems of ergodic problems of Hamilton-Jacobi equationsJan 16 2019Here, we address a uniqueness structure of viscosity solutions for ergodic problems of weakly coupled Hamilton-Jacobi systems. In particular, we study comparison principle with respect to generalized Mather measures as a generalization of the result proved ... More
64-pixel NbTiN superconducting nanowire single-photon detector array for spatially resolved photon detectionJan 31 2014We present the characterization of two-dimensionally arranged 64-pixel NbTiN superconducting nanowire single-photon detector array for spatially resolved photon detection. NbTiN films deposited on thermally oxidized Si substrates enabled the high-yield ... More
Low-Filling-Factor Superconducting Single Photon Detector with High System Detection EfficiencyMay 13 2013Nov 15 2013We designed, fabricated, and measured superconducting nanowire single-photon detectors (SSPDs) with low filling factor which achieve high system detection efficiency (SDE) and counting rate simultaneously. Numerical simulation reveals that high optical ... More
Image processing using miniKanrenMar 16 2014An integral image is one of the most efficient optimization technique for image processing. However an integral image is only a special case of delayed stream or memoization. This research discusses generalizing concept of integral image optimization ... More
Lightlike limit of the boosted Kerr black holes in higher-dimensional spacetimesDec 15 2004Feb 14 2005Deriving the gravitational field of the high-energy objects is an important theme because the black holes might be produced in particle collisions in the brane world scenario. In this paper, we develop a method for boosting the metric of the stationary ... More
Generalized orbifold Euler characteristics of symmetric orbifolds and covering spacesSep 07 2003Let G be a finite group and let M be a G-manifold. We introduce the concept of generalized orbifold invariants of M/G associated to an arbitrary group Gamma, an arbitrary Gamma-set, and an arbitrary covering space of a connected manifold Sigma whose fundamental ... More
Crosstalk-free operation of multi-element SSPD array integrated with SFQ circuit in a 0.1 Watt GM cryocoolerJul 17 2012We demonstrate the successful operation of a multi-element superconducting nanowire single-photon detector (SSPD) array integrated with a single-flux-quantum (SFQ) readout circuit in a compact 0.1 W Gifford-McMahon cryocooler. A time-resolved readout ... More
Stable string operations are trivialSep 26 2008We show that in closed string topology and in open-closed string topology with one $D$-brane, higher genus stable string operations are trivial. This is a consequence of Harer's stability theorem and related stability results on the homology of mapping ... More
Infinite Product Decomposition of Orbifold Mapping SpacesJun 07 2007Sep 30 2008Physicists showed that the generating function of orbifold elliptic genera of symmetric orbifolds can be written as an infinite product. We show that there exists a geometric factorization on space level behind this infinite product formula in much more ... More
Loop coproducts in string topology and triviality of higher genus TQFT operationsJun 08 2007Nov 16 2008Cohen and Godin constructed positive boundary topological quantum field theory (TQFT) structure on the homology of free loop spaces of oriented closed smooth manifolds by associating a certain operations called string operations to orientable surfaces ... More
Black hole initial data in Gauss-Bonnet gravity: Momentarily static caseFeb 09 2011We study the method for generating the initial data of black hole systems in Gauss-Bonnet (GB) gravity. The initial data are assumed to be momentarily static and conformally flat. Although the equation for the conformal factor is highly nonlinear, it ... More
Highly distorted apparent horizons and the hoop conjectureDec 23 2007By analyzing the apparent horizon (AH) formation in the collision of two pp-waves with rectangular sources in four dimensions, we study to what extent the AH can be distorted without violating the energy conditions. It is shown that the highly distorted ... More
On the existence of a static black hole on a braneDec 02 2008We study a static black hole localized on a brane in the Randall-Sundrum (RS) II braneworld scenario. To solve this problem numerically, we develop a code having the almost 4th-order accuracy. This code derives the highly accurate result for the case ... More
Generalized Orbifold Euler Characteristic of Symmetric Products and Equivariant Morava K-TheoryMar 27 2001We introduce the notion of generalized orbifold Euler characteristic associated to an arbitrary group, and study its properties. We then calculate generating functions of higher order (p-primary) orbifold Euler characteristic of symmetric products of ... More
A Homotopy Theoretic Proof of the BV Identity in Loop HomologyJun 08 2007Chas and Sullivan proved the existence of a Batalin-Vilkovisky algebra structure in the homology of free loop spaces on closed finite dimensional smooth manifolds using chains and chain homotopies. This algebraic structure involves an associative product ... More
TQFT string operations in open-closed string topologyMar 07 2008Sep 24 2008To open-closed cobordism surfaces, open-closed string topology associates topological quantum field theory (TQFT) operations, namely string operations, which depend only on homeomorphism types of surfaces and which satisfy the sewing property. We show ... More
On the Proof of Vanishing Cosmological Constant in String TheoryDec 15 2013The proof of 4-dimensional cosmological constant is given for the 10-dimensional supergravity-super-Yang-Mills theory. Supersymmetry is broken at will. The proof is very simple and it is based on the scale invariance of the theory but it assumes a nouvelle ... More
On uniqueness of static photon surface: Perturbative approachJul 25 2016A photon surface $S$ is defined as a three-dimensional timelike hypersurface such that any null geodesic initially tangent to $S$ continues to be included in $S$, like $r=3M$ of the Schwarzschild spacetime. Using analytic solutions to static perturbations ... More
Cap Products in String TopologyJun 07 2007Jul 11 2008Chas and Sullivan showed that the homology of the free loop space LM of an oriented closed smooth finite dimensional manifold M admits the structure of a Batalin-Vilkovisky (BV) algebra equipped with an associative product called the loop product and ... More
Batalin-Vilkovisky Lie Algebra Structure on the Loop Homology of Complex Stiefel ManifoldsMar 14 2007We determine the Batalin-Vilkovisky Lie algebra structure for the integral loop homology of special unitary groups and complex Stiefel manifolds. It is shown to coincide with the Poisson algebra structure associated to a certain odd symplectic form on ... More
Open-Closed TQFT String Operations for Disc Cobordisms, Simultaneous Saddle Interactions, and Constant Homology ClassesMar 07 2008Nov 20 2008Previously, we showed that most of the open-closed topological quantum field theory (TQFT) string operations vanish including all the higher genus TQFT operations, and we described a small list of genus zero open-closed TQFT string operations which can ... More
Size Distribution of Main-Belt Asteroids with High InclinationDec 28 2010We investigated the size distribution of high-inclination main-belt asteroids (MBAs) to explore asteroid collisional evolution under hypervelocity collisions of around 10 km/s. We performed a wide-field survey for high-inclination sub-km MBAs using the ... More
Reexamination of Finite-Lattice Extrapolation of Haldane GapsNov 14 2008We propose two methods of estimating a systematic error in extrapolation to the infinite-size limit in the study of measuring the Haldane gaps of the one-dimensional Heisenberg antiferromagnet with the integer spin up to S=5. The finite-size gaps obtained ... More
High-Precision Measurements of Brightness Variation of NereidDec 04 2012Nereid, a satellite of Neptune, has a highly eccentric prograde orbit with a semi-major axis larger than 200 Neptune radius and is classified as an irregular satellite. Although the capture origin of irregular satellites has been widely accepted, several ... More
H-vectors of simplicial complexes with Serre's conditionsDec 06 2009We study $h$-vectors of simplicial complexes which satisfy Serre's condition ($S_r$). We say that a simplicial complex $\Delta$ satisfies Serre's condition ($S_r$) if $\tilde H_i(\lk_\Delta(F);K)=0$ for all faces $F \in \Delta$ and for all $i < \min \{r-1,\dim ... More
Higgs Amplitude Mode in BCS Superconductors Nb$_{1-x}$Ti$_{x}$N induced by Terahertz Pulse ExcitationMay 02 2013Jul 09 2013Ultrafast responses of BCS superconductor Nb1-xTixN films in a nonadiabatic excitation regime were investigated by using terahertz (THz) pump-THz probe spectroscopy. After an instantaneous excitation with the monocycle THz pump pulse, a transient oscillation ... More
Optimal conditions for Bell test using spontaneous parametric down-conversion sourcesAug 25 2018We theoretically and experimentally investigate the optimal conditions for the Bell experiment using spontaneous parametric down conversion (SPDC) sources. In theory, we show that relatively large average photon number (typically $\sim$0.5) is desirable ... More
Arithmetical ranks of Stanley-Reisner ideals of simplicial complexes with a coneSep 12 2008When a cone is added to a simplicial complex $\Delta$ over one of its faces, we investigate the relation between the arithmetical ranks of the Stanley-Reisner ideals of the original simplicial complex and the new simplicial complex $\Delta'$. In particular, ... More
Collision of high-energy closed strings: Formation of a ring-like apparent horizonJun 30 2007Oct 18 2007We study collisions of two high-energy closed strings in the framework of $D$-dimensional general relativity. The model of a high-energy closed string is introduced as a {/it pp}-wave generated by a ring-shaped source with the radius $R$. At the instant ... More
Black ring formation in particle systemsApr 27 2004It is known that the formation of apparent horizons with non-spherical topology is possible in higher-dimensional spacetimes. One of these is the black ring horizon with $S^1\times S^{D-3}$ topology where $D$ is the spacetime dimension number. In this ... More
High-energy head-on collisions of particles and hoop conjectureApr 18 2002We investigate the apparent horizon formation for high-energy head-on collisions of particles in multi-dimensional spacetime. The apparent horizons formed before the instance of particle collision are obtained analytically. Using these solutions, we discuss ... More
Positive energy theorem implies constraints on static steller modelsSep 27 2006Nov 21 2006Using the positive energy theorem, we derive some constraints on static steller models in asymptotically flat spacetimes in a general setting without imposing spherical symmetry. We show that there exist no regular solutions under certain conditions on ... More
Bar-mode instability of rapidly spinning black hole in higher dimensions: Numerical simulation in general relativityApr 28 2010Numerical-relativity simulation is performed for rapidly spinning black holes (BHs) in a higher-dimensional spacetime of special symmetries for the dimensionality $6 \leq d \leq 8$. We find that higher-dimensional BHs, spinning rapidly enough, are dynamically ... More
Broken $S_3$ Symmetry in Flavor PhysicsNov 26 2010Dec 10 2010The $S_3$ symmetry is shown to be a very good approximate symmetry when it is broken in a specific way. This is true both in quark sector and in lepton sector. The way to break it is implied by the K-M mechanism applied not to the mixing matrix but to ... More
Black hole formation in the grazing collision of high-energy particlesSep 02 2002We numerically investigate the formation of D-dimensional black holes in high-energy particle collision with the impact parameter and evaluate the total cross section of the black hole production. We find that the formation of an apparent horizon occurs ... More
Higher-dimensional numerical relativity: Formulation and code testsJul 16 2009Dec 18 2009We derive a formalism of numerical relativity for higher-dimensional spacetimes and develop numerical codes for simulating a wide variety of five-dimensional (5D) spacetimes for the first time. First, the Baumgarte-Shapiro-Shibata-Nakamura formalism is ... More
The strict order property and generic automorphismsOct 30 2000If T is an model complete theory with the strict order property, then the theory of the models of T with an automorphism has no model companion.
5d/6d DE instantons from trivalent gluing of web diagramsFeb 23 2017Mar 17 2017We propose a new prescription for computing the Nekrasov partition functions of five-dimensional theories with eight supercharges realized by gauging non-perturbative flavor symmetries of three five-dimensional superconformal field theories. The topological ... More
Hilbert series and mixed branches of $T[SU(N)]$ theorySep 26 2016We consider mixed branches of 3d $\mathcal{N}=4$ $T[SU(N)]$ theory. We compute the Hilbert series of the Coulomb branch part of the mixed branch from a restriction rule acting on the Hilbert series of the full Coulomb branch that will truncate the magnetic ... More
Stanley--Reisner rings with large multiplicities are Cohen--MacaulayMar 10 2005We prove that certain class of Stanley--Reisner rings having sufficiently large multiplicities are Cohen--Macaulay using Alexander duality.
Buchsbaum Stanley--Reisner rings with minimal multiplicityDec 27 2003In this paper, we study non-Cohen--Macaulay Buchsbaum Stanley--Reisner rings with linear free resolution. In particular, for given integers $c$, $d$, $q$ with $c \ge 1$, $2 \le q \le d$, we give an upper bound $h_{c,d,q}$ on the dimension of the unique ... More
Nonaxisymmetric instability of rapidly rotating black hole in five dimensionsDec 18 2009We present results from numerical solution of Einstein's equation in five dimensions describing evolution of rapidly rotating black holes. We show, for the first time, that the rapidly rotating black holes in higher dimensions are unstable against nonaxisymmetric ... More
Word2Vec is a special case of Kernel Correspondence Analysis and Kernels for Natural Language ProcessingMay 17 2016Aug 14 2016We show Correspondence Analysis (CA) is equivalent to defining Gini-index with appropriate scaled one-hot encoding. Using this relation, we introduce non-linear kernel extension of CA. The extended CA gives well-known analysis for categorical data (CD) ... More
Probing the string axiverse by gravitational waves from Cygnus X-1Jul 08 2014Apr 18 2015In the axiverse scenario, a massive scalar field (string axion) forms a cloud around a rotating black hole (BH) by superradiant instability and emits continuous gravitational waves (GWs). We examine constraints on the string axion parameters that can ... More
Axiverse and Black HoleAug 05 2011Nov 11 2011String theory/M-theory generally predicts that axionic fields with a broad mass spectrum extending below 10^{-10}eV are produced after compactification to four dimensions. These axions/fields provoke a rich variety of cosmophysical phenomena on different ... More
Quantum Zeno effect in an unstable system with NMRSep 14 2012Mar 12 2013We theoretically propose a scheme for verification of quantum Zeno effect (QZE) to suppress a decay process with Nuclear Magnetic Resonance (NMR). Nuclear spins are affected by low frequency noise, and so one can naturally observe non-exponential decay ... More
Numerical Analysis of the Wave Function of the Multidimensional UniverseJul 22 2000In the framework of the Hartle-Hawking no-boundary proposal, we investigate quantum creation of the multidimensional universe with the cosmological constant $\Lambda$ but without matter fields. In this paper we solved the Wheeler-de Witt equation numerically. ... More
Dynamical Properties of Euclidean Solutions in a Multidimensional Cosmological ModelJul 22 2000In the framework of the Hartle-Hawking no-boundary proposal, we investigated quantum creation of the multidimensional universe with a cosmological constant ($\Lambda$) but without matter fields. We have found that the classical solutions of the Euclidean ... More
Cohen-Macaulayness of large powers of Stanley-Reisner idealsSep 04 2010We prove that for m > 2, the m-th symbolic power of a Stanley-Reisner ideal is Cohen-Macaulay if and only if the simplicial complex is a matroid. Similarly, the m-th ordinary power is Cohen-Macaulay for some m > 2 if and only if the complex is a complete ... More
Evolutionary simulations of autopoietic cells with cognitionDec 28 2015The minimal requirements for life are autopoiesis and cognition. We propose autopoietic models with cognition and perform three classes of evolutionary simulation. In our models the plasticity of the metabolic cycle and the regulation function of the ... More
Gravitational radiation from an axion cloud around a black hole: Superradiant phaseDec 09 2013Motivated by possible existence of string axions with ultralight masses, we study gravitational radiation from an axion cloud around a rotating black hole (BH). The axion cloud extracts the rotation energy of the BH by superradiant instability, while ... More
Coincidence analysis to search for inspiraling compact binaries using TAMA300 and LISM dataMar 21 2004Aug 29 2004Japanese laser interferometric gravitational wave detectors, TAMA300 and LISM, performed a coincident observation during 2001. We perform a coincidence analysis to search for inspiraling compact binaries. The length of data used for the coincidence analysis ... More
Exact partition functions of Higgsed 5d $T_N$ theoriesSep 01 2014Jan 19 2015We present a general prescription by which we can systematically compute exact partition functions of five-dimensional supersymmetric theories which arise in Higgs branches of the $T_N$ theory. The theories may be realized by webs of 5-branes whose dual ... More
Partition functions of web diagrams with an O7$^-$-planeSep 23 2016We consider the computation of the topological string partition function for 5-brane web diagrams with an O7$^-$-plane. Since upon quantum resolution of the orientifold plane these diagrams become non-toric web diagrams without the orientifold we are ... More
Deductive Inference for the Interiors and Exteriors of Horn TheoriesMar 03 2009In this paper, we investigate the deductive inference for the interiors and exteriors of Horn knowledge bases, where the interiors and exteriors were introduced by Makino and Ibaraki to study stability properties of knowledge bases. We present a linear ... More
Anomalous pairing vibration in neutron-rich Sn isotopes beyond the N=82 magic numberJun 09 2011Two-neutron transfer associated with the pair correlation in superfluid neutron-rich nuclei is studied with focus on low-lying $0^+$ states in Sn isotopes beyond the N=82 magic number. We describe microscopically the two-neutron addition and removal transitions ... More
Covariance and PCA for Categorical VariablesNov 28 2007Covariances from categorical variables are defined using a regular simplex expression for categories. The method follows the variance definition by Gini, and it gives the covariance as a solution of simultaneous equations. The calculated results give ... More
Solitonlike solutions of magnetostatic equilibria: Plane-symmetric caseMay 28 2008We present the plane-symmetric solitonlike solutions of magnetostatic equilibria by solving the nonlinear Grad-Shafranov (GS) equation numerically. The solutions have solitonlike and periodic structures in the $x$ and $y$ directions, respectively, and ... More
Topological vertex for Higgsed 5d $T_N$ theoriesMay 01 2015Aug 21 2015We analyse the computation of the partition function of 5d $T_N$ theories in Higgs branches using the topological vertex. The theories are realised by a web of $(p,q)$ 5-branes whose dual description may be given by an M-theory compactification on a certain ... More
Partition functions of web diagrams with an O7$^-$-planeSep 23 2016Oct 04 2016We consider the computation of the topological string partition function for 5-brane web diagrams with an O7$^-$-plane. Since upon quantum resolution of the orientifold plane these diagrams become non-toric web diagrams without the orientifold we are ... More
Word2Vec is a special case of Kernel Correspondence Analysis and Kernels for Natural Language ProcessingMay 17 2016Nov 25 2018We show that correspondence analysis (CA) is equivalent to defining a Gini index with appropriately scaled one-hot encoding. Using this relation, we introduce a nonlinear kernel extension to CA. This extended CA gives a known analysis for natural language ... More
Bosenova collapse of axion cloud around a rotating black holeMar 22 2012Motivated by possible existence of stringy axions with ultralight mass, we study the behavior of an axion field around a rapidly rotating black hole (BH) obeying the sine-Gordon equation by numerical simulations. Due to superradiant instability, the axion ... More
Pulsed Sagnac polarization-entangled photon source with a PPKTP crystal at telecom wavelengthNov 14 2013May 06 2014We demonstrate pulsed polarization-entangled photons generated from a periodically poled $\mathrm{KTiOPO_4}$ (PPKTP) crystal in a Sagnac interferometer configuration at telecom wavelength. Since the group-velocity-matching (GVM) condition is satisfied, ... More
Countermeasure against tailored bright illumination attack for DPS-QKDAug 10 2013We propose a countermeasure against the so-call tailored bright illumination attacl dor Differential-Phase-Shift QKD (DPS-QKD). By Monitoring a rate of coincidence detection at a pair of superconducting nanowire single photon detectors (SSPDs) which is ... More
Frequency-domain Hong-Ou-Mandel interferenceJan 05 2016Hong-Ou-Mandel (HOM) interference unveils a distinct behavior of identical particles which cannot be distinguished from each other. Especially for bosons, two separated identical particles passing through a beamsplitter always go together into one of ... More
R**2 correction to BMPV black hole entropy from Kerr/CFT correspondenceDec 22 2011Mar 19 2012Following Kerr/CFT correspondence, we compute the entropy of five-dimensional supersymmetric rotating BMPV black holes.We successfully reproduce Iyer-Wald formula in the presence of Gauss-Bonnet terms from the viewpoint of microscopic CFT. This further ... More
Charge-Transfer Matrix Elements by FMO-LCMO Approach: Hole Transfer in DNA with Parameter Tuned Range-Separated DFTApr 12 2016A scheme for computing charge-transfer matrix elements with the linear combination of fragment molecular orbitals and the 'nonempirically tuned range-separated' density functional is presented. It takes account of the self-consistent orbital relaxation ... More
Heralded single excitation of atomic ensemble via solid-state-based telecom photon detectionJul 06 2016Telecom photonic quantum networks with matter quantum systems enable a rich variety of applications, such as a long distance quantum cryptography and one-way quantum computing. Preparation of a heralded single excitation (HSE) in an atomic ensemble by ... More
Efficient detection of a highly bright photon source using superconducting nanowire single photon detectorsSep 05 2013May 06 2014We investigate the detection of an ultra-bright single-photon source using highly efficient superconducting nanowire single-photon detectors (SNSPDs) at telecom wavelengths. Both the single-photon source and the detectors are characterized in detail. ... More
Zeros of the first derivative of Dirichlet $L$-functionsApr 27 2016Y{\i}ld{\i}r{\i}m has classified zeros of the derivatives of Dirichlet $L$-functions into trivial zeros, nontrivial zeros and vagrant zeros. In this paper we remove the possibility of vagrant zeros for the first derivative $L'(s,\chi)$ of Dirichlet $L$-functions ... More
Zeros of the first derivative of Dirichlet $L$-functionsApr 27 2016Jan 03 2017Y\i ld\i r\i m has classified zeros of the derivatives of Dirichlet $L$-functions into trivial zeros, nontrivial zeros and vagrant zeros. In this paper we remove the possibility of vagrant zeros for $L'(s,\chi)$ when the conductors are large to some extent. ... More
Semi-Phenomenological Analysis of Dynamics of Nonlinear Excitations in One-Dimensional Electron-Phonon SystemMar 24 1996The structure of moving nonlinear excitations in one-dimensional electron-phonon systems is studied semi-phenomenologically by using an effective action in which the width of the nonlinear excitation is treated as a dynamical variable. The effective action ... More
High Ecliptic Latitude Survey for Small Main-Belt AsteroidsAug 15 2013Main-belt asteroids have been continuously colliding with one another since they were formed. Its size distribution is primarily determined by the size dependence of asteroid strength against catastrophic impacts. The strength scaling law as a function ... More
Cohen-Macaulay edge ideal whose height is half of the number of verticesSep 24 2009We consider a class of graphs $G$ such that the height of the edge ideal $I(G)$ is half of the number $\sharp V(G)$ of the vertices. We give Cohen-Macaulay criteria for such graphs.
Improved analysis of black hole formation in high-energy particle collisionsMar 23 2005May 01 2005We investigate formation of an apparent horizon (AH) in high-energy particle collisions in four- and higher-dimensional general relativity, motivated by TeV-scale gravity scenarios. The goal is to estimate the prefactor in the geometric cross section ... More
U(n) Spectral Covers from DecompositionMar 16 2012May 11 2012We construct decomposed spectral covers for bundles on elliptically fibered Calabi-Yau threefolds whose structure groups are S(U(1) x U(4)), S(U(2) x U(3)) and S(U(1) x U(1) x U(3)) in heterotic string compactifications. The decomposition requires not ... More
Schmitt-Vogel type lemma for reductionsDec 08 2009The lemma given by Schmitt and Vogel is an important tool in the study of arithmetical rank of squarefree monomial ideals. In this paper, we give a Schmitt-Vogel type lemma for reductions as an analogous result.
Black hole formation in the head-on collision of ultrarelativistic chargesMay 26 2006Aug 05 2006We study black hole formation in the head-on collision of ultrarelativistic charges. The metric of charged particles is obtained by boosting the Reissner-Nordstr\"om spacetime to the speed of light. Using the slice at the instant of collision, we study ... More
Efficient generation of twin photons at telecom wavelengths with 10 GHz repetition-rate tunable comb laserSep 10 2014Efficient generation and detection of indistinguishable twin photons are at the core of quantum information and communications technology (Q-ICT). These photons are conventionally generated by spontaneous parametric down conversion (SPDC), which is a ... More
Spectrally resolved Hong-Ou-Mandel interference between independent sourcesJul 09 2015Hong-Ou-Mandel (HOM) interference between independent photon sources (HOMI-IPS) is the fundamental block for quantum information processing, such as quantum gate, Shor's algorithm, Boson sampling, etc. All the previous HOMI-IPS experiments were carried ... More
Arithmetical rank of lexsegment edge idealsNov 15 2009Dec 08 2009Let $I\subset S=K[x_1,...,x_n]$ be a lexsegment edge ideal or the Alexander dual of such an ideal. In both cases it turns out that the arithmetical rank of $I$ is equal to the projective dimension of $S/I.$
On the radical of a monomial idealDec 07 2004Algebraic and combinatorial properties of a monomial ideal and its radical are compared.
Observation of two output light pulses from a partial wavelength converter preserving phase of an input light at a single-photon levelSep 11 2013Nov 07 2013We experimentally demonstrate that both a converted and an unconverted light pulses after wavelength conversion with various conversion efficiencies preserve phase information of an input light at a single-photon level. In our experiment, we converted ... More
Generation and distribution of high-dimensional frequency-entangled quditsMar 25 2016Mar 31 2016We demonstrate a novel scheme to generate frequency-entangled qudits with dimension number higher than 10 and to distribute them over optical fibers of 15 km in total length. This scheme combines the technique of spectral engineering of biphotons generated ... More
Modified E91 protocol demonstration with hybrid entanglement photon sourceJan 23 2015We report on an experimental demonstration of the modified Ekert 91 protocol of quantum key distribution using a hybrid entanglement source with two different degrees of freedoms, a 1550 nm time-bin qubit and 810 nm polarization qubit. The violation of ... More
Heralded amplification of nonlocality via entanglement swapping for long-distance device-independent quantum key distributionApr 12 2019To realize the practical implementation of device-independent quantum key distribution~(DIQKD), the main difficulty is that its security relies on the detection-loophole-free violation of the Clauser-Horne-Shimony-Holt~(CHSH) inequality, i.e. the CHSH ... More
High-fidelity conversion of photonic quantum information to telecommunication wavelength with superconducting single-photon detectorsJul 06 2012We experimentally demonstrate a high-fidelity visible-to-telecommunication wavelength conversion of a photon by using a solid-state-based difference frequency generation. In the experiment, one half of a pico-second visible entangled photon pair at 780 ... More
Feature Selection via L1-Penalized Squared-Loss Mutual InformationOct 06 2012Feature selection is a technique to screen out less important features. Many existing supervised feature selection algorithms use redundancy and relevancy as the main criteria to select features. However, feature interaction, potentially a key characteristic ... More
Reconfiguration of Cliques in a GraphDec 12 2014We study reconfiguration problems for cliques in a graph, which determine whether there exists a sequence of cliques that transforms a given clique into another one in a step-by-step fashion. As one step of a transformation, we consider three different ... More
A high visibility Hong-Ou-Mandel interference via a time-resolved coincidence measurementAug 17 2016We report on the observation of a high visibility Hong-Ou-Mandel interference of two heralded photons emitted from a spontaneous parametric down conversion~(SPDC) pumped by continuous-wave~(cw) light. A non-degenerate photon pair at 1541~nm and 1580~nm ... More
Non-classical two-photon interference between independent telecom light pulses converted by difference-frequency generationApr 01 2013We experimentally demonstrated the Hong-Ou-Mandel (HOM) interference between two photons after visible-to-telecommunication wavelength conversion. In the experiment, we prepared a heralded single photon by using spontaneous parametric down-conversion ... More
Notes on the algebraic curves in (p,q) minimal string theoryFeb 27 2006Nov 13 2006Loop amplitudes in (p,q) minimal string theory are studied in terms of the continuum string field theory based on the free fermion realization of the KP hierarchy. We derive the Schwinger-Dyson equations for FZZT disk amplitudes directly from the W_{1+\infty} ... More
Semiclassical instability of the brane-world: Randall-Sundrum bubblesAug 09 2001Aug 12 2001We discuss the semiclassical instability of the Randall-Sundrum brane-world model against a creation of a kind of Kaluza-Klein bubble. An example describing such a bubble space-time is constructed from the five-dimensional AdS-Schwarzschild metric. The ... More
Close-slow analysis for head-on collision of two black holes in higher dimensions: Bowen-York initial dataOct 24 2006Dec 20 2006Scenarios of large extra dimensions have enhanced the importance for the study of black holes in higher dimensions. In this paper, we analyze an axisymmetric system of two black holes. Specifically, the Bowen-York method is generalized for higher dimensions ... More
Phases, Flops and F-theory: SU(5) Gauge TheoriesApr 05 2013Oct 07 2013We consider F-theory and M-theory compactifications on singular Calabi-Yau fourfolds with an SU(5) singularity. On the M-theory side this realizes three-dimensional N=2 supersymmetric gauge theories with matter, and compactification on a resolution of ... More