Results for "Masahide Sasaki"

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Optimal parameter estimation of depolarizing channelMar 22 2002We investigate strategies for estimating a depolarizing channel for a finite dimensional system. Our analysis addresses the double optimization problem of selecting the best input probe state and the measurement strategy that minimizes the Bayes cost ... More
Experimental demonstration of entanglement assisted coding using a two-mode squeezed vacuum stateFeb 05 2004Oct 29 2004We have experimentally realized the scheme initially proposed as quantum dense coding with continuous variables [Ban, J. Opt. B \textbf{1}, L9 (1999), and Braunstein and Kimble, \pra\textbf{61}, 042302 (2000)]. In our experiment, a pair of EPR (Einstein-Podolski-Rosen) ... More
Fidelity and the communication of quantum informationJul 05 2001We compare and contrast the error probability and fidelity as measures of the quality of the receiver's measurement strategy for a quantum communications system. The error probability is a measure of the ability to retrieve {\it classical} information ... More
Discrimination of the binary coherent signal: Gaussian-operation limit and simple non-Gaussian near-optimal receiversJun 07 2007Aug 14 2008We address the limit of the Gaussian operations and classical communication in the problem of quantum state discrimination. We show that the optimal Gaussian strategy for the discrimination of the binary phase shift keyed (BPSK) coherent signal is a simple ... More
Quantum learning and universal quantum matching machineFeb 28 2002Suppose that three kinds of quantum systems are given in some unknown states $\ket f^{\otimes N}$, $\ket{g_1}^{\otimes K}$, and $\ket{g_2}^{\otimes K}$, and we want to decide which \textit{template} state $\ket{g_1}$ or $\ket{g_2}$, each representing ... More
Entangled state based on nonorthogonal stateJan 04 2001Properties of entangled states based on nonorthogonal states are clarified. Especially, it is shown that they can have complete degree of entanglement.
Multiphoton discrimination at telecom wavelength with charge integration photon detectorMar 04 2005We present a charge integration photon detector (CIPD) that enables the efficient measurement of photon number states at the telecom-fiber wavelengths with a quantum efficiency of 80% and a resolution less than 0.5 electrons at 1 Hz sampling. The CIPD ... More
Retrodiction of Generalised Measurement OutcomesMay 15 2002Nov 01 2002If a generalised measurement is performed on a quantum system and we do not know the outcome, are we able to retrodict it with a second measurement? We obtain a necessary and sufficient condition for perfect retrodiction of the outcome of a known generalised ... More
Conditional generation of an arbitrary superposition of coherent statesFeb 13 2007We present a scheme to conditionally generate an arbitrary superposition of a pair of coherent states from a squeezed vacuum by means of the modified photon subtraction where a coherent state ancilla and two on/off type detectors are used. We show that, ... More
Photon number resolving detection at telecom wavelength with a charge integration photon detectorDec 09 2005We demonstrate multiphoton discrimination at telecom wavelength with the readout frequency of 40 Hz by charge integration photon detector (CIPD). The CIPD consists of an InGaAs pin photodiode and a GaAs junction field effect transistor as a pre-amplifier ... More
Maintenance-free Operation of WDM Quantum Key Distribution System through a Field Fiber over 30 DaysAug 05 2013Maintenance-free wavelength-division-multiplexing quantum key distribution for 30 days was achieved through a 22-km field fiber. Using polarization-independent interferometers and stabilization techniques, we attained a quantum bit error rate as low as ... More
Quantum tele-amplification with a continuous variable superposition stateNov 28 2012Nov 12 2013Optical coherent states are classical light fields with high purity, and are essential carriers of information in optical networks. If these states could be controlled in the quantum regime, allowing for their quantum superposition (referred to as a Schr\"odinger ... More
The Quantumness of a Set of Quantum StatesFeb 13 2003This article is an introduction to quant-ph/0302092. We propose to quantify how "quantum" a set of quantum states is. The quantumness of a set is the worst-case difficulty of transmitting the states through a classical communication channel. Potential ... More
Squeezing Quantum Information through a Classical Channel: Measuring the "Quantumness" of a Set of Quantum StatesFeb 11 2003Jul 29 2003In this paper we propose a general method to quantify how "quantum" a set of quantum states is. The idea is to gauge the quantumness of the set by the worst-case difficulty of transmitting the states through a purely classical communication channel. Potential ... More
Wiretap Channels with Causal State Information: Strong SecrecyAug 01 2017Mar 23 2019The coding problem for wiretap channels with causal channel state information available at the encoder and/or the decoder is studied under the strong secrecy criterion. This problem consists of two aspects: one is due to naive wiretap channel coding and ... More
Generation of cosmological large lepton asymmetry from a rolling scalar fieldNov 12 2002Sep 09 2003We propose a new scenario to simultaneously explain a large lepton asymmetry and a small baryon asymmetry. We consider a rolling scalar field and its derivative coupling to the lepton number current. The presence of an effective nonzero time derivative ... More
Scaling property and peculiar velocity of global monopolesJul 23 2001Feb 05 2002We investigate the scaling property of global monopoles in the expanding universe. By directly solving the equations of motion for scalar fields, we follow the time development of the number density of global monopoles in the radiation dominated (RD) ... More
Growth Law of Bunch Size in Step Bunching Induced by Flow in SolutionDec 06 2010By carrying out Monte Carlo simulations,we study step bunching during solution growth. For simplicity, we consider a square lattice, which represents a diffusion field in a solution, and express the diffusion of atoms as the hopping of atoms on the lattice ... More
Supersymmetric DBI inflationMay 07 2012Oct 18 2012We discuss a supersymmetric version of DBI (Dirac-Born-Infeld) inflation, which is a typical inflation model in string cosmology. The supersymmetric DBI action together with a superpotential always leads to correction terms associated with the potential ... More
Experimental transmission of quantum digital signatures over 90-km of installed optical fiber using a differential phase shift quantum key distribution systemAug 15 2016Quantum digital signatures apply quantum mechanics to the problem of guaranteeing message integrity and non-repudiation with information-theoretical security, which are complementary to the confidentiality realized by quantum key distribution. Previous ... More
Self-Assembly Formed by Spherical Patchy Particles with Long-Range AttractionJun 29 2019We report on self-assemblies formed from spherical patchy particles interacting by a long-range attraction through a patch region in a two-dimensional system. We performed Monte Carlo simulations to find stable structures in a system with constant number ... More
On odd dimensional complex analytic Kleinian groupsJul 28 2017Sep 18 2018We shall explain here an idea to generalize classical complex analytic Kleinian group theory to any odd dimensional cases. For a certain class of discrete subgroups of $\PGL_{2n+1}(\C)$ acting on $\P^{2n+1}$, we can define their domains of discontinuity ... More
Continuous variable teleportation as a generalized thermalizing quantum channelFeb 28 2002A quantum channel is derived for continuous variable teleportation which is performed by means of an arbitrary entangled state and the standard protocol. When a Gaussian entangled state such as a two-mode squeezed-vacuum state is used, the continuous ... More
Binary projective measurement via linear optics and photon countingMar 09 2006Mar 19 2006We investigate the implementation of binary projective measurements with linear optics. This problem can be viewed as a single-shot discrimination of two orthogonal pure quantum states. We show that any two orthogonal states can be perfectly discriminated ... More
Large amplitude coherent state superposition generated by a time-separated two-photon subtraction from a continuous wave squeezed vacuumApr 03 2008Jun 18 2008Theoretical analysis is given for a two-photon subtraction from a continuous wave (CW) squeezed vacuum with finite time separation between two detection events. In the CW photon subtraction process, the generated states are inevitably described by temporal ... More
Average Secrecy Capacity of Free-Space Optical Communication Systems with On-Off Keying Modulation and Threshold DetectionJan 24 2016This paper considers secure communication over free-space optical (FSO) links suffering from turbulence-induced fading. In particular, we study the average secrecy capacity of applying physical layer security to achieve security in an FSO communication ... More
Full analysis of multi-photon pair effects in spontaneous parametric down conversion based photonic quantum information processingOct 14 2014May 07 2015In spontaneous parametric down conversion (SPDC) based quantum information processing (QIP) experiments, there is a tradeoff between the coincide count rates (i.e. the pumping power of the SPDC), which limits the rate of the protocol, and the visibility ... More
Unambiguous quantum state filteringApr 04 2003In this paper, we consider the generalized measurement where one particular quantum signal is unambiguously extracted from a set of non-commutative quantum signals and the other signals are filtered out. Simple expressions for the maximum detection probability ... More
Practical scheme for the optimal measuremnet in quantum interferometric devicesDec 06 2002Mar 26 2003We apply a Kennedy-type detection scheme, which was originally proposed for a binary communications system, to interferometric sensing devices. We show that the minimum detectable perturbation of the proposed system reaches the ultimate precision bound ... More
Ultrahigh-sensitivity high-linearity photodetection system using a low-gain avalanche photodiode with an ultralow-noise readout circuitMar 04 2005A highly sensitive photodetection system with a detection limit of 1 photon/s was developed. This system uses a commercially available 200-mm-diameter silicon avalanche photodiode (APD) and an in-house-developed ultralow-noise readout circuit, which are ... More
Temporally multiplexed superposition states of continuous variablesApr 02 2008Apr 08 2008We study non-Gaussian states generated by two-photon subtraction from a cw squeezed light source. In a cw scheme one can subtract two photons from the source with a designated time separation and can genarate temporally multiplexed superposition states ... More
Invariance of the bit error rate in the ancilla-assisted homodyne detectionMar 22 2010We investigated the minimum achievable bit error rate of discriminating binary coherent states by homodyne measurements with the help of arbitrary ancilla states coupled via beam splitters. We took into account arbitrary pure ancillary states those were ... More
Reliability and Secrecy Functions of the Wiretap Channel under Cost ConstraintJul 02 2013Aug 19 2014The wiretap channel has been devised and studied first by Wyner, and subsequently extended to the case with non-degraded general wiretap channels by Csiszar and Korner. Focusing mainly on the Poisson wiretap channel with cost constraint, we newly introduce ... More
Ultra fast quantum key distribution over a 97 km installed telecom fiber with wavelength-division multiplexing clock synchronizationMay 15 2008Jun 23 2008We demonstrated ultra fast BB84 quantum key distribution (QKD) transmission at 625 MHz clock rate through a 97 km field-installed fiber using practical clock synchronization based on wavelength-division multiplexing (WDM). We succeeded in over-one-hour ... More
Experimental Determination of the Gain Distribution of an Avalanche Photodiode at Low GainsDec 04 2008A measurement system for determining the gain distributions of avalanche photodiodes (APDs) in a low gain range is presented. The system is based on an ultralow-noise charge--sensitive amplifier and detects the output carriers from an APD. The noise of ... More
Towards practical device-independent quantum key distribution with spontaneous parametric downconversion sources, on-off photodetectors and entanglement swappingDec 21 2015Jan 13 2016Device-independent quantum key distribution (DIQKD) guarantees unconditional security of secret key without making assumptions about the internal workings of the devices used. It does so using the loophole-free violation of a Bell's inequality. The primary ... More
Quantum channel of continuous variable teleportation and nonclassicality of quantum statesOct 05 2001Noisy teleportation of nonclassical quantum states via a two-mode squeezed-vacuum state is studied with the completely positive map and the Glauber-Sudarshan $P$-function. Using the nonclassical depth as a measure of transmission performance, we compare ... More
Realization of a collective decoding of codeword statesJan 07 1998This was also extended from the previous article quant-ph/9705043, especially in a realization of the decoding process.
Entanglement evaluation of non-Gaussian states generated by photon subtraction from squeezed statesDec 09 2005Feb 22 2006We consider the problem of evaluating the entanglement of non-Gaussian mixed states generated by photon subtraction from entangled squeezed states. The entanglement measures we use are the negativity and the logarithmic negativity. These measures possess ... More
Open Virtual Structure Constants and Mirror Computation of Open Gromov-Witten Invariants of Projective HypersurfacesAug 24 2011In this paper, we generalize Walcher's computation of the open Gromov-Witten invariants of the quintic hypersurface to Fano and Calabi-Yau projective hypersurfaces. Our main tool is the open virtual structure constants. We also propose the generalized ... More
Extended Slow-Roll Conditions and Primordial Fluctuations: Multiple Scalar Fields and Generalized GravityOct 29 2008Dec 04 2008As an extension of our previous study, we derive slow-roll conditions for multiple scalar fields which are non-minimally coupled with gravity and for generalized gravity theories of the form $f(\phi,R)$. We provide simple formulae of the spectral indices ... More
Effective squeezing enhancement via measurement-induced non-Gaussian operation and its application to dense coding schemeMar 04 2005May 18 2005We study the measurement-induced non-Gaussian operation on the single- and two-mode \textit{Gaussian} squeezed vacuum states with beam splitters and on-off type photon detectors, with which \textit{mixed non-Gaussian} states are generally obtained in ... More
Development of SNSPD System with Gifford-McMahon CryocoolerMar 02 2010A superconducting nanowire single photon detector (SNSPD) system for telecommunication wavelength using a GM cryocooler was developed and its performance was verified. The cryocooler based SNSPD system can operate continuously with a 100 V AC power supply ... More
A simple quantum channel having superadditivity of channel capacityMay 26 1997When classical information is sent through a quantum channel of nonorthogonal states, there is a possibility that transmittable classical information exceeds a channel capacity in a single use of the initial channel by extending it into multi-product ... More
Compactly packaged superconducting nanowire single-photon detector with an optical cavity for multichannel systemFeb 28 2010We developed superconducting nanowire single-photon detectors with an optical cavity (OC-SNSPDs) for multichannel systems. For efficient coupling, the devices were installed in compact fiber-coupled packages after their substrate thickness was reduced ... More
Characteristics of superconducting single photon detector in DPS-QKD system under bright illumination blinding attackAug 10 2013We derive the time-dependent photo-detection probability equation of a superconducting single photon detector (SSPD) to study the responsive property for a pulse train at high repetition rate. Using this equation, we analyze the characteristics of SSPDs ... More
Numerical Study on Secrecy Capacity and Code Length Dependence of the Performances in Optical Wiretap ChannelsSep 14 2015Secrecy issues of free-space optical links realizing information theoretically secure communications as well as high transmission rates are discussed. We numerically study secrecy communication rates of optical wiretap channel based on on-off keying modulation ... More
7 dB quadrature squeezing at 860 nm with periodically-poled KTiOPO4Feb 03 2006Aug 15 2006We observed -7.2 dB quadrature squeezing at 860 nm by using a sub-threshold continuous-wave pumped optical parametric oscillator with a periodically-poled KTiOPO4 crystal as a nonlinear optical medium. The squeezing level was measured with the phase of ... More
Quantum channels showing superadditivity in capacityJan 08 1998This was significantly extended from the previous article quant-ph/9705043,especially in an information theoretic aspect, by adding new results.
Unambiguous discrimination among oracle operatorsFeb 26 2007Jul 08 2007We address the problem of unambiguous discrimination among oracle operators. The general theory of unambiguous discrimination among unitary operators is extended with this application in mind. We prove that entanglement with an ancilla cannot assist any ... More
Entanglement quantification with Fisher informationDec 13 2006We show that the Fisher information associated with entanglement-assisted coding has a monotonic relationship with the logarithmic negativity, an important entanglement measure, for certain classes of continuous variable (CV) quantum states of practical ... More
Implementation of projective measurements with linear optics and continuous photon countingOct 18 2004Mar 04 2005We investigate the possibility of implementing a given projection measurement using linear optics and arbitrarily fast feedforward based on the continuous detection of photons. In particular, we systematically derive the so-called Dolinar scheme that ... More
Photon level crosstalk between parallel fibers installed in urban areaAug 05 2010We estimate the channel characteristics of field-installed dark fibers at single photon levels for quantum key distribution (QKD). Measured fibers are telecom single-mode dark fibers over 45 km connecting a center and suburbs of Tokyo. Their total losses ... More
Multi-channel SNSPD system with high detection efficiency at telecommunication wavelengthApr 01 2010We developed a four-channel superconducting nanowire single-photon detector system based on a Gifford-McMahon cryocooler. All channels showed a system detection efficiency (at a 100 Hz dark-count rate) higher than 16% at 1550 nm wavelength, and the best ... More
Open Mirror Symmetry for Higher Dimensional Calabi-Yau HypersurfacesJul 29 2015Aug 17 2015Compactifications with fluxes and branes motivate us to study various enumerative invariants of Calabi-Yau manifolds. In this paper, we study non-perturbative corrections depending on both open and closed string moduli for a class of compact Calabi-Yau ... More
Exceeding classical capacity limit in quantum optical channelApr 04 2003The amount of information transmissible through a communications channel is determined by the noise characteristics of the channel and by the quantities of available transmission resources. In classical information theory, the amount of transmissible ... More
Wavelength division multiplexed and double-port pumped time-bin entangled photon pair generation using Si ring resonatorFeb 09 2017We report a wavelength division multiplexed time-bin entangled photon pair source in telecom wavelength using a 10 {\mu}m radius Si ring resonator. This compact resonator has two add ports and two drop ports. By pumping one add port by a continuous laser, ... More
Quantum receivers with squeezing and photon-number-resolving detectorsFeb 12 2013Apr 16 2013We propose quantum receivers with optical squeezing and photon-number-resolving detector (PNRD) for the near-optimal discrimination of quaternary phase-shift-keyed coherent state signals. The basic scheme is similar to the previous proposals (e.g. Phys. ... More
Exact Kahler Potential for Calabi-Yau FourfoldsFeb 15 2013May 19 2013We study quantum Kahler moduli space of Calabi-Yau fourfolds. Our analysis is based on the recent work by Jockers et al. which gives a novel method to compute the Kahler potential on the quantum Kahler moduli space of Calabi-Yau manifold. In contrast ... More
Multi-Point Virtual Structure Constants and Mirror Computation of CP^2-modelMay 05 2013In this paper, we propose a geometrical approach to mirror computation of genus 0 Gromov-Witten invariants of CP^2. We use multi-point virtual structure constants, which are defined as intersection numbers of a compact moduli space of quasi maps from ... More
Scaling Law for the Distribution of Fluctuations of Share VolumeFeb 24 2003Mar 17 2006We show power-scaling behaviors for fluctuations in share volume, which no other studies have so far done. After analyzing a database of the daily transactions for all securities listed on the Tokyo Stock Exchange, we selected 1050 large companies that ... More
Chaotic hybrid new inflation in supergravity with a running spectral indexJul 30 2003Nov 07 2003We propose an inflation model in supergravity, in which chaotic and hybrid inflation occurs successively, followed by new inflation. During hybrid inflation, adiabatic fluctuations with a running spectral index with $\ns >1$ on a large scale and $\ns ... More
Excited Baryon Spectroscopy from Lattice QCD: Finite Size Effect and Hyperfine Mass SplittingMar 19 2005Jul 01 2005A study of the finite-size effect is carried out for spectra of both ground-state and excited-state baryons in quenched lattice QCD using Wilson fermions. Our simulations are performed at beta=6.2 with three different spatial sizes, La~1.6, 2.2 and 3.2 ... More
Quantum receiver beyond the standard quantum limit of coherent optical communicationMar 29 2011The most efficient modern optical communication is known as coherent communication and its standard quantum limit (SQL) is almost reachable with current technology. Though it has been predicted for a long time that this SQL could be overcome via quantum ... More
Sub-shot-noise-limit discrimination of on-off keyed coherent signals via a quantum receiver with a superconducting transition edge sensorFeb 15 2010We demonstrate a sub-shot-noise-limit discrimination of on-off keyed coherent signals by an optimal displacement quantum receiver in which a superconducting transition edge sensor is installed. Use of a transition edge sensor and a fiber beam splitter ... More
QKD from a microsatellite: the SOTA experienceOct 26 2018The transmission and reception of polarized quantum-limited signals from space is of capital interest for a variety of fundamental-physics experiments and quantum-communication protocols. Specifically, Quantum Key Distribution (QKD) deals with the problem ... More
Widely tunable single photon source with high purity at telecom wavelengthMar 25 2013We theoretically and experimentally investigate the spectral tunability and purity of photon pairs generated from spontaneous parametric down conversion in periodically poled $\mathrm{KTiOPO_4}$ crystal with group-velocity matching condition. The numerical ... More
Experimental realization of optimal detection strategies for overcomplete statesAug 04 2000Mar 05 2001We present the results of generalized measurements of optical polarization designed to provide one of three or four distinct outcomes. This has allowed us to discriminate between nonorthogonal polarization states with an error probability that is close ... More
Projective measurement onto arbitrary superposition of coherent state basesFeb 21 2017Feb 15 2018One of the peculiar features in quantum mechanics is that a superposition of macroscopically distinct states can exits. In optical system, this is highlighted by a superposition of coherent states (SCS), i.e. a superposition of classical states. Recently ... More
Photon subtraction from traveling fields - recent experimental demonstrationsApr 21 2011We review our most recent results on application of the photon subtraction technique for optical quantum information processing primitives, in particular entanglement distillation and generation of squeezed qubit states. As an introduction we provide ... More
Accessible information and optimal strategies for real symmetrical quantum sourcesDec 22 1998Jan 18 1999We study the problem of optimizing the Shannon mutual information for sources of real quantum states i.e. sources for which there is a basis in which all the states have only real components. We consider in detail the sources ${\cal E}_M$ of $M$ equiprobable ... More
Satellite-to-ground quantum communication using a 50-kg-class micro-satelliteJul 12 2017Recent rapid growth in the number of satellite-constellation programs for remote sensing and communications, thanks to the availability of small-size and low-cost satellites, provides impetus for high capacity laser communication (lasercom) in space. ... More
Generation of large-amplitude coherent-state superposition via ancilla-assisted photon-subtractionJun 18 2008Dec 05 2008We propose and demonstrate a novel method to generate a large-amplitude coherent-state superposition (CSS) via ancilla-assisted photon-subtraction. The ancillary mode induces quantum interference of indistinguishable processes, widening the controllability ... More
Displacement receiver for phase-shift-keyed coherent statesAug 09 2012Quantum receiver is an important tool for overcoming the standard quantum limit (SQL) of discrimination errors in optical communication. We theoretically study the quantum receivers for discriminating ternary and quaternary phase shift keyed coherent ... More
Optical phase estimation via coherent state and displaced photon countingApr 15 2016Jun 21 2016We consider the phase sensing via weak optical coherent state at quantum limit precision. A new detection scheme for the phase estimation is proposed which is inspired by the suboptimal quantum measurement in coherent optical communication. We theoretically ... More
Highly efficient entanglement swapping and teleportation at telecom wavelengthOct 01 2014Entanglement swapping at telecom wavelengths is at the heart of quantum networking in optical fiber infrastructures. Although entanglement swapping has been demonstrated experimentally so far using various types of entangled photon sources both in near-infrared ... More
Conclusive Precision Bounds for SU(1,1) InterferometersOct 18 2018In this paper, we revisit the quantum Fisher information (QFI) calculation in SU(1,1) interferometer considering different phase configurations. When one of the input modes is a vacuum state, we show by using phase averaging, different phase configurations ... More
Optimum detection for extracting maximum information from symmetric qubit setsJun 29 2001Sep 06 2001We demonstrate a class of optimum detection strategies for extracting the maximum information from sets of equiprobable real symmetric qubit states of a single photon. These optimum strategies have been predicted by Sasaki et al. [Phys. Rev. A{\bf 59}, ... 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
Non-Gaussian entanglement distillation for continuous variablesJul 13 2009Entanglement distillation is an essential ingredient for long distance quantum communications. In the continuous variable setting, Gaussian states play major roles in quantum teleportation, quantum cloning and quantum cryptography. However, entanglement ... More
Temperature Dependent Performances of Superconducting Nanowire Single-Photon Detectors in an Ultralow-Temperature RegionSep 21 2010We present the performances of a superconducting nanowire single-photon detector (SNSPD) in an ultralow-temperature region from 16 mK to 4 K. The system detection efficiency of the SNSPD showed saturation in the bias-current and temperature dependences, ... More
Unbreakable distributed storage with quantum key distribution network and password-authenticated secret sharingJul 02 2016Distributed storage plays an essential role in realizing robust and secure data storage in a network over long periods of time. A distributed storage system consists of a data owner machine, multiple storage servers and channels to link them. In such ... More
Optical continuous-variable qubitFeb 17 2010In a new branch of quantum computing, information is encoded into coherent states, the primary carriers of optical communication. To exploit it, quantum bits of these coherent states are needed, but it is notoriously hard to make superpositions of such ... More
Time-bin entangled photon pair generation from Si micro-ring resonatorJan 23 2015We demonstrate time-bin entanglement generation in telecom wavelength using a 7 {\mu}m radius Si micro-ring resonator pumped by a continuous wave laser. The resonator structure can enhance spontaneous four wave mixing, leading to a photon pair generation ... More
Practical purification scheme for decohered coherent-state superpositions via partial homodyne detectionOct 31 2005Aug 02 2006We present a simple protocol to purify a coherent-state superposition that has undergone a linear lossy channel. The scheme constitutes only a single beam splitter and a homodyne detector, and thus is experimentally feasible. In practice, a superposition ... More
Exactly solvable potentials with finitely many discrete eigenvalues of arbitrary choiceFeb 22 2014We address the problem of possible deformations of exactly solvable potentials having finitely many discrete eigenvalues of arbitrary choice. As Kay and Moses showed in 1956, reflectionless potentials in one dimensional quantum mechanics are exactly solvable. ... More
Reflection Bootstrap Equations for Toda Field TheoryNov 04 1993An algebraic approach to integrable quantum field theory with a boundary (a half line) is presented and interesting algebraic equations, Reflection equations (RE) and Reflection Bootstrap equations (RBE) are discussed. The Reflection equations are a consistent ... More
Symmetric Morse potential is exactly solvableNov 18 2016Morse potential $V_M(x)= g^2\exp (2x)-g(2h+1)\exp(x)$ is defined on the full line, $-\infty<x<\infty$ and it defines an exactly solvable 1-d quantum mechanical system with finitely many discrete eigenstates. By taking its right half $0\le x<\infty$ and ... More
Molecular Chemical Engines: Pseudo-Static Processes and the Mechanism of Energy TransductionAug 01 2005We propose a simple theoretical model for a molecular chemical engine that catalyzes a chemical reaction and converts the free energy released by the reaction into mechanical work. Binding and unbinding processes of reactant and product molecules to and ... More
Gauge-independent Thermal $β$ Function In Yang-Mills Theory via the Pinch TechniqueDec 27 1995Jan 12 1996It is proposed to use the pinch technique (PT) to obtain the gauge-independent thermal $\beta$ function $\beta_T$ in a hot Yang-Mills gas. Calculations of the thermal $\beta$ function are performed at one-loop level in four different gauges, (i) the background ... More
Charge Screening Effect in Metallic Carbon NanotubesDec 11 2001Charge screening effect in metallic carbon nanotubes is investigated in a model including the one-dimensional long-range Coulomb interaction. It is pointed out that an external charge which is being fixed spatially is screened by internal electrons so ... More
Vacuum structure of Toroidal Carbon NanotubesJun 11 2001Oct 12 2001Low energy excitations in carbon nanotubes can be described by an effective field theory of two components spinor. It is pointed out that the chiral anomaly in 1+1 dimensions should be observed in a metallic toroidal carbon nanotube on a planar geometry ... More
On link diagrams that are minimal with respect to Reidemeister moves I and IIDec 02 2016In this paper, a link diagram is said to be minimal if no Reidemeister move I or II can be applied to it to reduce the number of crossings. We show that for an arbitrary diagram D of a link without a trivial split component, a minimal diagram obtained ... More
Calculation of Binding Energies for Fractional Quantum Hall States with Even DenominatorsMar 14 2007Fractional quantum Hall states with even denominators have the following specific properties: states with filling factors nu=5/8, 7/10, 3/8, 3/10, and so on have respective local minima in the experimental curve of diagonal resistivity Rxx versus magnetic ... More
Consideration of ac Josephson Effect in Fractional Quantum Hall StatesJul 02 2008The ac Josephson effect phenomenon is studied in fractional quantum Hall states (FQHS). Usual quantum Hall devices have an electron layer of uniform thickness. We consider a new quantum Hall device. The device has a narrow part that is vertical to the ... More
Differential Geometry and Integrability of the Hamiltonian System of a Closed Vortex FilamentOct 24 1995Mar 29 1996The system of a closed vortex filament is an integrable Hamiltonian one, namely, a Hamiltonian system with an infinite sequense of constants of motion in involution. An algebraic framework is given for the aim of describing differential geometry of this ... More
Gap Condition and Self-Dualized ${\cal N}=4$ Super Yang-Mills Theory for ADE Gauge Group on K3Mar 20 2003Apr 21 2003We try to determine the partition function of ${\cal N}=4$ super Yang-Mills theoy for ADE gauge group on K3 by self-dualizing our previous ADE partition function. The resulting partition function satisfies gap condition.
Reformulation of the Stochastic Potential Switching Algorithm and a Generalized Fourtuin-Kasteleyn RepresentationJan 07 2010Aug 30 2010A new formulation of the stochastic potential switching algorithm is presented. This reformulation naturally leads us to a generalized Fourtuin-Kasteleyn representation of the partition function Z. A formula for internal energy E and that of heat capacity ... More
Latent Semantic Word Sense Disambiguation Using Global Co-occurrence InformationMar 05 2014In this paper, I propose a novel word sense disambiguation method based on the global co-occurrence information using NMF. When I calculate the dependency relation matrix, the existing method tends to produce very sparse co-occurrence matrix from a small ... More
Gauge-independent resummed gluon self-energy in hot QCDNov 16 1996The pinch technique (PT) is applied to obtain the gauge-independent resummed gluon self-energy in a hot Yang-Mills gas. Calculation is performed at one- loop level in linear gauges which preserve rotational invariance and the res ummed propagators and ... More