Masao Kitano

Masao Kitano
Kyoto University | Kyodai · Headquarter

Doctor of Engineering

About

118
Publications
21,378
Reads
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2,550
Citations
Additional affiliations
October 2014 - present
Kyoto University
Position
  • Executive Vice President
Description
  • (Eduation, Information Infrastructure, and Evaluation)
April 2013 - September 2014
Kyoto University
Position
  • Managing Director
April 2012 - March 2014
Kyoto University
Position
  • Head of Faculty
Education
April 1975 - March 1977
Kyoto University
Field of study
  • Department of Electronics, Graduate School of Engineering
April 1971 - March 1975
Kyoto University
Field of study
  • Department of Electronics, Faculty of Engieering

Publications

Publications (118)
Chapter
Electromagnetic property of a medium can be derived from electric and/or magnetic response of constituent atoms or molecules. If an artificial structure called meta-atom is designed to show the same response for the incidence of electromagnetic waves, the assembly of the meta-atoms, or metamaterial, is expected to exhibit the same functionality as...
Chapter
The storage of light is one of the most significant applications of electromagnetically induced transparency (EIT) effects in atomic systems. It is also possible to mimic the EIT effect using artificial media, or metamaterials, which are based on coupled resonators. This chapter focuses on metamaterials that realize the storage and retrieval of ele...
Article
Full-text available
We developed an optical frequency comb based on a Yb:KYW laser. Soft-aperture Kerr-lens mode-locking at the cavity transverse-mode degeneration enabled us to generate 360 mW from a 750 mW pump laser diode. This resulted in spectral broadening over one octave using just a photonic crystal fiber. We achieved a free-running linewidth of 15 kHz in the...
Article
Full-text available
We investigate the storage and retrieval of electromagnetic waves using a nonlinear metamaterial, analogous to the electromagnetically induced transparency (EIT) observed in atomic systems. We experimentally demonstrate the storage of the electromagnetic wave by reducing an auxiliary “control” wave; the stored wave is then released by recovering th...
Article
Full-text available
We phase lock an octave-spanning optical frequency comb, generated using a mode-locked titanium–sapphire laser and a photonic-crystal fiber, to a continuous-wave laser line-narrowed to a reference cavity. To phase lock the pulse-repetition frequency, the cavity length of the mode-locked laser is controlled by using a fast piezoelectric-actuated mir...
Article
Full-text available
In this paper, we show that the handedness of a planar chiral checkerboard-like metasurface can be dynamically switched by modulating the local sheet impedance of the metasurface structure. We propose a metasur- face design to realize the handedness switching and theoretically analyze its electromagnetic characteristic based on Babinet’s principle....
Article
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The electromagnetic properties of an extremely thin metallic checkerboard drastically change from resonant reflection (transmission) to resonant transmission (reflection) when the local electrical conductivity at the interconnection points of the checkerboard is switched. To date, such critical transitions of metasurfaces have been applied only whe...
Article
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We demonstrate that a self-complementary checkerboard-like metasurface works as a broadband coherent perfect absorber (CPA) when symmetrically illuminated by two counter-propagating incident waves. A theoretical analysis based on wave interference and the results of numerical simulations of the proposed metasurface are provided. In addition, we exp...
Article
We report on our system and scheme for single-ion spectroscopy of the 2S1/2(F=0)-2D3/2(F=2) clock transition in ¹⁷¹Yb⁺. Spectroscopy of the clock transition requires decoupling of the 2D3/2(F=2) state from the laser cooling cycle. We investigate this decoupling of the 2D3/2(F=2) state by using independent light sources for driving of all the transi...
Article
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We investigate the supersymmetry (SUSY) structures for inductor-capacitor circuit networks on a simple regular graph and its line graph. We show that their eigenspectra must coincide (except, possibly, for the highest eigenfrequency) due to SUSY, which is derived from the topological nature of the circuits. To observe this spectra correspondence in...
Article
Full-text available
Quantum-optical coherence tomography (Q-OCT) provides a dispersion-canceled axial-imaging method, but its practical use is limited by the weakness of the light source and by artifacts in the images. A recent study using chirped-pulse interferometry (CPI) has demonstrated dispersion-canceled and artifact-free OCT with a classical system; however, un...
Article
Full-text available
This paper proposes a reconfigurable planar metamaterial that can be switched between capacitive and inductive responses using local changes in the electrical conductivity of its constituent material. The proposed device is based on Babinet’s principle and exploits the singular electromagnetic responses of metallic checkerboard structures, which ar...
Article
Full-text available
We demonstrate a nonradiative flat band for spoof surface plasmon polaritons bounded on a structured surface with Lieb lattice symmetry in the terahertz regime. First, we theoretically derive the dispersion relation of spoof plasmons in a metallic Lieb lattice based on the electrical circuit model. We obtain three bands, one of which is independent...
Conference Paper
We demonstrate frequency measurement of a clock laser for the 2S1/2 - 2D3/2 transition in 171Yb+ by using a comb based on a mode-locked Yb:KYW laser. Phase locking of the comb to the laser is also achieved.
Article
Full-text available
We propose a metamaterial to realize true electromagnetically induced transparency (EIT), where the incidence of an auxiliary electromagnetic wave called the control wave induces transparency for a probe wave. The analogy to the original EIT effect in an atomic medium is shown through analytical and numerical calculations derived from a circuit mod...
Article
Full-text available
We experimentally observed nonlinear variations in the three-vertex geometric phase in a two- photon polarization qutrit. The three-vertex geometric phase is defined by three quantum states, which generally forms a three-state (qutrit) system. By changing one of the three constituent states, we observed two rapid increases in the three-vertex geome...
Article
Full-text available
This research resolves a long-standing problem on the electromagnetic response of self-complementary metallic screens with checkerboardlike geometry. Although Babinet's principle implies that they show a frequency-independent response, this unusual characteristic has not been observed yet due to the singularities of the metallic point contacts in t...
Article
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We propose a classical optical interferometry scheme that reproduces dispersion-insensitive Hong-Ou-Mandel interferograms. The interferometric scheme is derived from a systematic method based on the time-reversal symmetry of quantum mechanics. The scheme uses a time-reversed version of a Hong-Ou-Mandel interferometer with pairs of orthogonally pola...
Article
We generate an octave-spanning optical frequency comb using laser-diode-pumped Yb:KYW laser without an optical amplifier. The laser maintains mode-locking over one week. The offset and pulse-repetition frequencies are tightly phase locked to a radiofrequency reference.
Article
Full-text available
A linear-to-circular polarization converter with half transmission and half reflection using a single- layered metamaterial is theoretically and numerically demonstrated. The unit cell of the metamate- rial consists of two coupled split-ring resonators with identical dimensions. A theoretical analysis based on an electrical circuit model of the cou...
Conference Paper
We report classical optical interferometry reproducing dispersion-insensitive Hong-Ou-Mandel interferograms. Our scheme is based on the time-reversal symmetry of quantum dynamics. We achieved high-visibility Hong-Ou-Mandel interferograms owing to simplicity of our setup.
Article
Full-text available
We experimentally demonstrate control over the group delay of narrow-band (quasi continuous wave) terahertz (THz) pulses with constant amplitude based on optical switching of a metasurface characteristic. The near-field coupling between resonant modes of a complementary split ring resonator pair and a rectangular slit show an electromagnetically in...
Article
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We theoretically and numerically investigate metamaterials composed of coupled resonators with indirect coupling. First, we theoretically analyze a mechanical model of coupled resonators with indirect coupling. The theoretical analysis shows that an electromagnetically induced transparency (EIT)-like phenomenon with a transparency bandwidth narrowe...
Article
Full-text available
We observed two-photon phase super-resolution in an unbalanced Michelson interferometer with classical Gaussian laser pulses. Our work is a time-reversed version of a two-photon interference experiment using an unbalanced Michelson interferometer. A measured interferogram exhibits two-photon phase super-resolution with a high visibility of 97.9% \p...
Article
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We investigate theoretically electromagnetic plane-wave scattering by self-complementary metasurfaces. By using Babinet's principle extended to metasurfaces with resistive elements, we show that the frequency-independent transmission and reflection are realized for normal incidence of a circularly polarized plane wave onto a self-complementary meta...
Conference Paper
We experimentally and numerically investigate spectral response that resembles electromagnetically induced transparency (EIT) phenomenon by using two planar metamaterials. The one of them consists of a cut wire (CW) with low quality factor and two SRRs with high quality factor, the other consists of a split ring resonator (SRR) with high quality fa...
Conference Paper
We determined the unperturbed frequencies of the 6S-8S two-photon transitions in cesium by evaluation of systematic frequency shifts of the lasers stabilized to the transition, together with frequency measurement with an octave-spanning optical frequency comb.
Article
Full-text available
We report numerical and experimental investigations into modulation instability in a nonlinear magnetoinductive waveguide. By numerical simulation we find that modulation instability occurs in an electrical circuit model of a magnetoinductive waveguide with third-order nonlinearity. We fabricate the nonlinear magnetoinductive waveguide for microwav...
Article
Full-text available
We investigate the mathematical structure of unit systems and the relations between them. Looking over the entire set of unit systems, we can find a mathematical structure that is called preorder (or quasi-order). For some pair of unit systems, there exists a relation of preorder such that one unit system is transferable to the other unit system. T...
Article
Full-text available
We propose a method for dynamically controlling the properties of a metamaterial that mimics electromagnetically induced transparency (EIT) by introducing varactor diodes to manipulate the structural symmetry of the metamaterial. Dynamic modulation of the EIT property enables the storage and retrieval of electromagnetic waves. We confirmed that the...
Article
Full-text available
Weak measurements with mixed probe states were investigated in the presence of noise in the probe system. We show that the completely mixed state can be used as a probe state for weak measurements of imaginary weak values. The completely mixed probe state has some advantages in terms of noise tolerance. We also experimentally demonstrated weak meas...
Article
We formulate a general method to analyze hybridization modes in metamaterials by employing electrical circuit models. By rewriting circuit equations for coupled inductor–capacitor circuit networks in the bra-ket notation, we show that there exists a good analogy between circuit models and quantum tight-binding models in solid-state physics. Our pic...
Article
Full-text available
We realize variable control of the group velocity in an electromagnetically induced transparency-like metamaterial. Its unit cell is designed to have a radiative mode and a trapped mode. The coupling strength between these two modes is determined by the electromagnetic field gradient. In this metamaterial with field-gradient-induced transparency, t...
Article
We investigated the electromagnetic properties of the metamaterials that consist of double-gap split ring resonators (SRRs) in the terahertz region. We found that varying the position of one gap with respect to the other causes the resonant frequency of the SRRs to shift over a broad range. This frequency shift is attributed to the change in the co...
Conference Paper
We pursue high frequency stability by using a large number of thermal atoms to investigate a possibility of local oscillators in the optical frequency standards. We frequency stabilize an extended-cavity laser diode to the 6S-8S two-photon transition in cesium atoms. We evaluated the frequency stability to be 4.4×10-14 at an averaging time of τ = 1...
Article
Full-text available
In a recent paper, Mansuripur et al. indicated and numerically verified the generation of the helical wavefront of optical beams using a conical-shape reflector. Because the optical reflection is largely free from chromatic aberrations, the conical reflector has an advantage of being able to manipulate the helical wavefront with broadband light suc...
Article
Full-text available
We study the dispersion relation of a metamaterial composed of metallic disks and bars arranged to have kagome symmetry and find that a plasmonic flat band is formed by the topological nature of the kagome lattice. To confirm the flat-band formation, we fabricate the metamaterial and make transmission measurements in the terahertz regime. Two bands...
Article
Full-text available
We present an effective method to generate second harmonic (SH) waves using nonlinear metamaterial composed of coupled split ring resonators (CSRRs) with varactor (variable capacitance) diodes. The CSRR structure has two resonant modes: a symmetric mode that resonates at the fundamental frequency and an anti-symmetric mode that resonates at the SH...
Article
Full-text available
In this review, we describe recent developments in func-tional metamaterials based on coupled resonators. We first consider coupled resonator metamaterials that mimic electromagnetically in-duced transparency (EIT). We present a circuit model for EIT-like metamaterials and introduce a new coupled resonator in which the coupling is provided by a fie...
Article
We investigate the loading rate of Yb+ ions loaded through photoionization in a radiofrequency trap. The absolute or relative number of the loaded trapped ions is measured by use of an electric resonance of the secular motion. This method is applicable even in the presence of anharmonicity. In two-color photoionization, where the first-excitation l...
Article
Full-text available
The properties of the geometric phases between three quantum states are investigated in a high-dimensional Hilbert space using the Majorana representation of symmetric quantum states. We found that the geometric phases between the three quantum states in an N -state quantum system can be represented by N − 1 spherical triangles on the Bloch sphere....
Article
We present a method to measure the geometric phase defined for three internal states of a photon (polarizations) using a three‐beam interferometer. From the interferogram, we can extract the geometric phase related to the three states as the area of a triangle formed by interference fringes. Unlike the conventional methods, our method does not inv...
Article
Full-text available
We investigate second harmonic (SH) generation in a doubly resonant metamaterial. We show that SH generation can be enhanced when the resonant condition is satisfied for the SH frequency as well as for the fundamental frequency. A unit cell of the doubly resonant metamaterial consists of two coupled resonators, one of which resonates at the fundame...
Article
Full-text available
We investigate a dynamically controllable electromagnetically induced transparency-like metamaterial. The unit structure of the metamaterial consists of a low-quality-factor resonator and a high-quality-factor resonator. The field gradient of the incident electromagnetic wave in the transverse direction induces coupling between these two types of r...
Article
We demonstrate a simple method that can be used to detect minor isotope lines in a saturated absorption spectrum by the absorption filtering of major isotope lines. We investigate this method for use in the spectroscopy of the 1S0-1P1 transition in Yb at 399 nm by controlling the density of Yb atoms by varying the discharge current of a hollow cath...
Article
Full-text available
In this study, we observe the nonlinear behavior of the two-photon geometric phase for polarization states using time-correlated photons pairs. This phase manifests as a shift of two-photon interference fringes. Under certain arrangements, the geometric phase can vary nonlinearly and become very sensitive to a change in the polarization state. More...
Article
Full-text available
Over 100 μW of continuous-wave tunable ultraviolet radiation at 370 nm is generated by the sum- frequency mixing of radiation from two extended-cavity laser diodes having powers of 60 mW at 822 nm and 8 mW at 671 nm in a lithium iodate crystal. The crystal is placed in an external cavity that enhances the powers of two fundamental beams simultaneou...
Article
Full-text available
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, ou...
Article
Full-text available
We investigate the mechanism of weak measurement by using an interferometric framework. In order to appropriately elucidate the interference effect that occurs in weak measurement, we introduce an interferometer for particles with internal degrees of freedom. It serves as a framework common to quantum eraser and weak measurement. We demonstrate tha...
Article
We investigate the mechanism of weak measurement by using an interferometric framework. In order to appropriately elucidate the interference effect that occurs in weak measurement, we introduce an interferometer for particles with internal degrees of freedom. We demonstrate that the geometric phase, particularly the Pancharatnam phase, results from...
Article
Full-text available
We introduce a simple experiment involving a double-slit interferometer by which one can learn basic concepts of quantum interference such as which-path marking, quantum erasers, and geometric phases. Each of them exhibits seemingly mysterious phenomena in quantum physics. In our experiment, we use the double-slit interference of visible light with...
Article
Full-text available
For dissipation-free photon-photon interaction at the single photon level, we analyze one-photon transition and two-photon transition induced by photon pairs in three-level atoms using two-photon wavefunctions. We show that the two-photon absorption can be substantially enhanced by adjusting the time correlation of photon pairs. We study two typica...
Article
Full-text available
When an antireflection-coated normal-cut nonlinear crystal is used in an external cavity for the generation of high second-harmonic power, a small residual reflection at the crystal facets causes a round-trip loss and prevents the realization of a large fundamental enhancement. This problem is eliminated when the reflected beams at the crystal face...
Article
We observe two-photon interference of photon pairs from a photonic crystal fiber with the help of an unbalanced Mach-Zehnder interferometer. Two-photon interference fringes with 83% visibility, which exceed the classical limit of 50%, are obtained. The correlation time of the photon pairs is roughly estimated to be 0.2 ps
Article
Full-text available
We investigate a method to produce photon pairs by four-wave mixing in photonic crystal fibers (PCFs). By controlling the wavelength of the pump light, which determines the phase matching condition for four-wave mixing, we can obtain a broader spectrum of photon pairs than undesired Raman-scattered photons. We observe two-photon interference of pho...
Article
Full-text available
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 th...
Article
We introduce a simple experiment involving a double-slit interferometer by which one can learn basic concepts of quantum interference such as which-path marking, quantum erasers, and geometric phases. Each of them exhibits seemingly mysterious phenomena in quantum physics. In our experiment, we use the double-slit interference of visible light with...
Article
Full-text available
It has been pointed out that for some types of measurement the Heisenberg uncertainty relation seems to be violated. In order to save the situation a new uncertainty relation was proposed by Ozawa. Here we introduce revised definitions of error and disturbance taking into account the gain associated with generalized measurement interactions. With t...
Article
Full-text available
We investigated Berry's phase for noncyclic evolution using the rotation of a polarization azimuth of linearly polarized light in a partially wound optical fiber over the surface of a cylinder. Using a rotation gauge around the rotation axis, the observed rotation of the polarization azimuth corresponds to the area of a spherical rectangle over the...
Article
Full-text available
It is shown that the magnetic force between thin, semi-infinite solenoids obeys a Coulomb-type law, which corresponds to that for magnetic monopoles placed at the end points of each solenoid. We derive the magnetic Coulomb law from the basic principles of electromagnetism, namely from the Maxwell equations and the Lorentz force.
Article
Full-text available
In electromagnetism, the vacuum impedance $Z_0$ is a universal constant, which is as important as the velocity of light $c$ in vacuum. Unfortunately, however, its significance does not seem to be appreciated so well and sometimes the presence itself is ignored. It is partly because in the Gaussian system of units, which has widely been used for lon...
Article
Full-text available
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...
Article
The carrier envelope phase (CEP) stabilizer of the 12-fs Ti:sapphire oscillator with chirp-mirror compensation consists of the so-called f-to-2f interferometry, the phase-detection and phase-locking electronics with a frequency divider of frep/4 and the controller of the CW pump power through a feedback based on the acousto-optic modulator (AOM). A...
Article
Full-text available
We present an electronic circuit which simulates wave propagation in dispersive media. The circuit is an array of phase shifter composed of operational amplifiers and can be described with a discretized version of one-dimensional wave equation for envelopes. The group velocity can be changed both spatially and temporarily. It is used to emulate slo...
Article
Full-text available
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 p...
Article
Full-text available
We present a simple electronic circuit which provides negative group delays for band-limited baseband pulses. It is shown that large time advancement comparable to the pulsewidth 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...
Article
Full-text available
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-fr...
Article
The quantum Zeno effect is a paradoxical phenomenon where the inhibition of transition or the guidance of system is realized with no losses in spite of the use of dissipative processes. It is universal and not limited to quantum systems. In this paper as a classical example we report the quantum Zeno effect in optical fibers. The fibers are spliced...