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  2. Takuya Hirano

Takuya Hirano

  (平野 琢也)

Profile Information

Affiliation
Professor, Faculty of Science, Department of Physics, Gakushuin University
Degree
(BLANK)(The University of Tokyo)
Contact information
takuya.hiranogakushuin.ac.jp
J-GLOBAL ID
200901062696389245
researchmap Member ID
1000246127
External link

Research Interests

 5

Research Areas

 2

Research History

 7
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Education

 4

Committee Memberships

 17
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Awards

 1

Papers

 98
  • Junnosuke Takai, Kosuke Shibata, Naota Sekiguchi, Takuya Hirano
    Physical Review A, May 11, 2023  
  • Jorge Amari, Junnosuke Takai, Takuya Hirano
    Optics Continuum, Apr 15, 2023  
  • Aki Torii, Kosuke Shibata, Yujiro Eto, Takuya Hirano
    Optics Express, 30(15) 26120-26120, Jul 18, 2022  Peer-reviewed
    We report on the waveguide-based generation of pulsed squeezed light at 795 nm, suitable for quantum enhanced measurements with rubidium atoms. Pulsed ultraviolet second harmonic light with a power of more than 400 mW is produced using a periodically poled LiNbO3 (PPLN) waveguide and is injected into another PPLN waveguide to generate quadrature squeezing. We find that the phase of the second harmonic pulse is shifted within a pulse, and we attribute the shift to heating due to blue-light induced infrared absorption (BLIIRA) from a comparison between the experiment and a numerical simulation. A squeezing level of −1.5(1) dB is observed in homodyne detection when we apply a linear phase shift to the local oscillator. The experiment and simulation imply that the squeezing level can be further improved by reducing BLIIRA.
  • Naota Sekiguchi, Kosuke Shibata, Aki Torii, Hiroyuki Toda, Ryohei Kuramoto, Daiki Fukuda, Takuya Hirano
    Physical Review A, 104(4), Oct 28, 2021  Peer-reviewed
  • Yujiro Eto, Takuya Hirano
    Japanese Journal of Applied Physics, 60(5), May, 2021  Peer-reviewed
    Second-harmonic generation (SHG) using periodically poled material in the high-conversion regime is investigated experimentally and theoretically. In the experiment, we use nanosecond pulses and periodically poled MgO:LiNbO3 waveguides with two lengths, 8.3 and 3.6 mm. In both waveguides, the conversion efficiency reaches 80% with increasing pump power and then decreases. The reduction in efficiency is more prominent for the long waveguide. For a peak power of the fundamental wave exceeding 140 W, stronger SHG is achieved by using the short waveguide. To understand these phenomena, we numerically investigate the effect of the cascaded nonlinear phase shift caused by the quasi-phase-matched SHG. The nonlinear phase shift induces an energy backflow to the fundamental wave even when effective phase matching is satisfied, and it greatly reduces the conversion efficiency, at the same level of power as the experiment.
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Misc.

 262
  • Taguchi Y, Masuyama Y, Sekine S, Fukitsuka K, Miwa I, Tojo S, Hirano T
    Meeting abstracts of the Physical Society of Japan, 66(1) 195-195, Mar 3, 2011  
  • Koshio A, Sakurai J, Horie K, Eto Y, Hirano T
    Meeting abstracts of the Physical Society of Japan, 66(1) 199-199, Mar 3, 2011  
  • Murayama K, Ido T, Kawasoe R, Hirano T
    Meeting abstracts of the Physical Society of Japan, 66(1) 199-199, Mar 3, 2011  
  • Yujiro Eto, Yun Zhang, Takuya Hirano
    OPTICS EXPRESS, 19(2) 1360-1366, Jan, 2011  
    We experimentally demonstrate transporting continuous quantum variables of individual light pulses at telecommunication wavelengths by using continuous-variable Bell measurements and post-processing displacement techniques. Time-domain pulsed homodyne detectors are used in the Bell measurements and the quantum variables of input light are transported pulse-by-pulse. Fidelity of F = 0.57 +/- 0.03 is experimentally achieved with the aid of entanglement, which is higher than the bound (F(c) = 0.5) of the classical case in the absence of entanglement. (C) 2011 Optical Society of America
  • Satoshi Tojo, Yoshihisa Taguchi, Yuta Masuyama, Taro Hayashi, Hiroki Saito, Takuya Hirano
    PHYSICAL REVIEW A, 82(3) 033609, Sep, 2010  
    We investigate controlled phase separation of a binary Bose-Einstein condensate in the proximity of a mixed-spin-channel Feshbach resonance in the vertical bar F = 1, m(F) = +1 > and vertical bar F = 2, mF = -1 > states of Rb-87 at a magnetic field of 9.10 G. Phase separation occurs on the lower-magnetic-field side of the Feshbach resonance while the two components overlap on the higher-magnetic-field side. The Feshbach resonance curve of the scattering length is obtained from the shape of the atomic cloud by comparison with the numerical analysis of coupled Gross-Pitaevskii equations.
  • Masuyama Y, Taguchi Y, Sekine S, Fukitsuka K, Miwa I, Tojo S, Hirano T
    Meeting abstracts of the Physical Society of Japan, 65(2) 137-137, Aug 18, 2010  
  • Ido T, Murayama K, Kawasoe R, Hirano T
    Meeting abstracts of the Physical Society of Japan, 65(2) 154-154, Aug 18, 2010  
  • Yoshimura M, Nonaka A, Sugaya T, Hirano T, Kikuchi K, Sugiura K, Kurimura S, Nakajima H
    Meeting abstracts of the Physical Society of Japan, 65(2) 154-154, Aug 18, 2010  
  • 早瀬 潤子, 岩本 敏, 江馬 一弘, 佐々木 雅英, 宅間 宏, 竹内 繁樹, 武岡 正裕, 武居 弘樹, 中村 泰信, 平野 琢也, 森山 園子
    應用物理, 79(8) 700-702, Aug 10, 2010  
  • Takeshi Kuwamoto, Hayato Usuda, Satoshi Tojo, Takuya Hirano
    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 79(3) 034004, Mar, 2010  
    We studied the dynamics of quadruply quantized vortices in Rb-87 Bose-Einstein condensates. Vortices were created in magnetically trapped condensates with hyperfine spin F = 2 by employing topological phase imprinting technique, wherein the direction of atomic spin is adiabatically reversed by applying a bias magnetic field. Vortices were observed for a holding time of up to 10 ms. Disappearance of the vortices was attributed to considerable expansion and excitation of the condensates, which were caused by the distortion of the magnetic potential. In order to observe the long-term behavior of the vortices, we transferred the condensates to a crossed-type optical dipole force trap after creating the vortices. In this case, the vortices were observed for a holding time of up to 22 ms. We also observed density profiles, which indicated the presence of split vortices.
  • Taguchi Y, Tanabe T, Kurihara M, Suzuki Y, Tojo S, Hirano T
    Meeting abstracts of the Physical Society of Japan, 65(1) 205-205, Mar 1, 2010  
  • HIRANO Takuya
    Japanese journal of optics, 39(1) 23-28, Jan 10, 2010  
  • Satoshi Tojo, Taro Hayashi, Tatsuyoshi Tanabe, Takuya Hirano, Yuki Kawaguchi, Hiroki Saito, Masahito Ueda
    PHYSICAL REVIEW A, 80(4) 042704, Oct, 2009  
    We studied spin-dependent two-body inelastic collisions in F=2 (87)Rb Bose-Einstein condensates both experimentally and theoretically. The (87)Rb condensates were confined in an optical trap and selectively prepared in various spin states in the F=2 manifold at a magnetic field of 3.0 G. The measured atom loss rates depend on the spin states of colliding atoms. We measured two fundamental loss coefficients for two-body inelastic collisions with total spins of 0 and 2. The loss coefficients determine the loss rates of all the spin pairs. The experimental results for mixtures of all spin combinations are in good agreement with numerical solutions of the Gross-Pitaevskii equations that include the effect of a magnetic field gradient.
  • Tanabe T, Taguchi Y, Tojo S, Hirano T
    Meeting abstracts of the Physical Society of Japan, 64(2) 89-89, Aug 18, 2009  
  • Tojo S, Tanabe T, Taguchi Y, Hirano T
    Meeting abstracts of the Physical Society of Japan, 64(2) 89-89, Aug 18, 2009  
  • Yujiro Eto, Akihiro Nonaka, Yun Zhang, Takuya Hirano
    PHYSICAL REVIEW A, 79(5) 050302, May, 2009  
    We propose and demonstrate a scheme to stably generate quadrature-entangled optical pulses using a ring interferometer composed of an optical parametric amplifier and a dispersive media. The entangled light pulses at telecommunication wavelength are generated by combining two squeezed beams. In our scheme, the relative phase between the two beams is kept stable by the ring interferometer and is controllable using dispersive media. The amplitude and phase quadratures of the entangled beams are measured using two time-domain pulsed homodyne detectors. When the relative phase is fixed at pi/2, we verify the inseparability of the states by a sufficient criterion <Delta(2)[X(a)(phi(0))+X(b)(pi-phi(0))]>+<Delta(2)[X(a)(phi(')(0))-X(b)(-phi(')(0))]>=0.64 < 1 where phi(')(0)-phi(0)=pi/2.
  • Yujiro Eto, Akihiro Nonaka, Yun Zhang, Takuya Hirano
    PHYSICAL REVIEW A, 79(5) 050302, May, 2009  
    We propose and demonstrate a scheme to stably generate quadrature-entangled optical pulses using a ring interferometer composed of an optical parametric amplifier and a dispersive media. The entangled light pulses at telecommunication wavelength are generated by combining two squeezed beams. In our scheme, the relative phase between the two beams is kept stable by the ring interferometer and is controllable using dispersive media. The amplitude and phase quadratures of the entangled beams are measured using two time-domain pulsed homodyne detectors. When the relative phase is fixed at pi/2, we verify the inseparability of the states by a sufficient criterion <Delta(2)[X(a)(phi(0))+X(b)(pi-phi(0))]>+<Delta(2)[X(a)(phi(')(0))-X(b)(-phi(')(0))]>=0.64 < 1 where phi(')(0)-phi(0)=pi/2.
  • Okubo R, Hirano M, Zhang Y, Hirano T
    Meeting abstracts of the Physical Society of Japan, 64(1) 143-143, Mar 3, 2009  
  • Eto Yujiro, Zhang Yun, Hirano Takuya
    Meeting abstracts of the Physical Society of Japan, 64(1) 143-143, Mar 3, 2009  
  • Hayashi T, Tojo S, Tanabe T, Inoue E, Hiraro T
    Meeting abstracts of the Physical Society of Japan, 64(1) 186-186, Mar 3, 2009  
  • S. Tojo, A. Tomiyama, M. Iwata, T. Kuwamoto, T. Hirano
    APPLIED PHYSICS B-LASERS AND OPTICS, 93(2-3) 403-407, Nov, 2008  
    We experimentally observed the time dependence of the spin populations of spin-2 87Rb Bose-Einstein condensates confined in an optical trap. The condensed atoms were initially populated in the stretched states |F=2,m (F) =+2, and |F=2,m (F) =-2 with several varieties of population imbalances. No spin-exchange collisions were observed in a weak magnetic field of 45 mG. The atom loss rate depended on the observed relative population of spin-states. We calculated the loss rate due to two-body inelastic collisions with the population imbalance using an experimentally estimated rate of 17.0(+/- 1.9)x10-14 cm3ss-1supercript stop under the population balance. The calculations were in good agreement with the measurements. Our results show that the dependence of inelastic collisions on spin channels plays an important role in the time-evolution of spin populations.
  • S. Tojo, A. Tomiyama, M. Iwata, T. Kuwamoto, T. Hirano
    APPLIED PHYSICS B-LASERS AND OPTICS, 93(2-3) 403-407, Nov, 2008  
    We experimentally observed the time dependence of the spin populations of spin-2 87Rb Bose-Einstein condensates confined in an optical trap. The condensed atoms were initially populated in the stretched states |F=2,m (F) =+2, and |F=2,m (F) =-2 with several varieties of population imbalances. No spin-exchange collisions were observed in a weak magnetic field of 45 mG. The atom loss rate depended on the observed relative population of spin-states. We calculated the loss rate due to two-body inelastic collisions with the population imbalance using an experimentally estimated rate of 17.0(+/- 1.9)x10-14 cm3ss-1supercript stop under the population balance. The calculations were in good agreement with the measurements. Our results show that the dependence of inelastic collisions on spin channels plays an important role in the time-evolution of spin populations.
  • 平野 琢也
    数理科学, 46(11) 31-36, Nov, 2008  
  • Tanabe T, Inoue E, Hayashi T, Tojo S, Hirano T
    Meeting abstracts of the Physical Society of Japan, 63(2) 95-95, Aug 25, 2008  
  • Hirano M, Okubo R, Zhang Y, Hirano T
    Meeting abstracts of the Physical Society of Japan, 63(2) 125-125, Aug 25, 2008  
  • Miyano S, Ido T, Hirano T
    Meeting abstracts of the Physical Society of Japan, 63(2) 126-126, Aug 25, 2008  
  • Yujiro Eto, Takashi Tajima, Yun Zhang, Takuya Hirano
    OPTICS EXPRESS, 16(14) 10650-10657, Jul, 2008  
    We report on the generation of quadrature squeezed light at 1.535 mu m via single-pass optical parametric amplification in a periodically poled MgO:LiNbO3 waveguide, and detection with a temporally shaped local oscillator. Squeezing of -4.1 dB was directly measured using the shaped local oscillator. Classical parametric gain of the shaped pulse was also investigated; a deamplification gain of -12.1 dB was observed with the amplification gain of only +13.8 dB. We experimentally show that the use of shaped pulse as local oscillator in homodyne detection allows us efficient squeezing detection with near-unit mode-matching efficiency. (c) 2008 Optical Society of America.
  • Ryuhi Okubo, Mayumi Hirano, Yun Zhang, Takuya Hirano
    OPTICS LETTERS, 33(13) 1458-1460, Jul, 2008  
    We report pulsed homodyne detection of squeezed pulses at a repetition rate of 76 MHz. Measurement of individual pulses, which were interrogated by the correlation coefficient between adjacent pulses, was realized. A homodyne detector was constructed using a low-noise, high-speed operational amplifier; it had a usable bandwidth of 250 MHz. We observed 2.3 dB of squeezing in both the time and frequency domains. (C) 2008 Optical Society of America.
  • Yujiro Eto, Takashi Tajima, Yun Zhang, Takuya Hirano
    OPTICS EXPRESS, 16(14) 10650-10657, Jul, 2008  
    We report on the generation of quadrature squeezed light at 1.535 mu m via single-pass optical parametric amplification in a periodically poled MgO:LiNbO3 waveguide, and detection with a temporally shaped local oscillator. Squeezing of -4.1 dB was directly measured using the shaped local oscillator. Classical parametric gain of the shaped pulse was also investigated; a deamplification gain of -12.1 dB was observed with the amplification gain of only +13.8 dB. We experimentally show that the use of shaped pulse as local oscillator in homodyne detection allows us efficient squeezing detection with near-unit mode-matching efficiency. (c) 2008 Optical Society of America.
  • Ryuhi Okubo, Mayumi Hirano, Yun Zhang, Takuya Hirano
    OPTICS LETTERS, 33(13) 1458-1460, Jul, 2008  
    We report pulsed homodyne detection of squeezed pulses at a repetition rate of 76 MHz. Measurement of individual pulses, which were interrogated by the correlation coefficient between adjacent pulses, was realized. A homodyne detector was constructed using a low-noise, high-speed operational amplifier; it had a usable bandwidth of 250 MHz. We observed 2.3 dB of squeezing in both the time and frequency domains. (C) 2008 Optical Society of America.
  • Tojo S, Hayashi T, Tanabe T, Hirano T
    Meeting abstracts of the Physical Society of Japan, 63(1) 186-186, Feb 29, 2008  
  • Tokunaga S, Miyano S, Hirano T
    Meeting abstracts of the Physical Society of Japan, 63(1) 176-176, Feb 29, 2008  
  • Zhang Y, Okubo R, Hirano M, Hirano T
    Meeting abstracts of the Physical Society of Japan, 63(1) 176-176, Feb 29, 2008  
  • Eto Y, Nonaka A, Zhang Y, Hirano T
    Meeting abstracts of the Physical Society of Japan, 63(1) 176-176, Feb 29, 2008  
  • 平野琢也
    数理科学, (545), 2008  
  • Okubo R, Hirano M, Zhang Y, Hirano T
    Meeting abstracts of the Physical Society of Japan, 62(2) 191-191, Aug 21, 2007  
  • Eto Y, Nonaka A, Zhang Y, Hirano T
    Meeting abstracts of the Physical Society of Japan, 62(2) 192-192, Aug 21, 2007  
  • Yun Zhang, Tatsuya Furuta, Ryuhi Okubo, Kosuke Takahashi, Takuya Hirano
    PHYSICAL REVIEW A, 76(1) 012314, Jul, 2007  
    We report on the generation of broadband pulsed quadrature entanglement by combining two squeezed vacua, which are generated from two degenerate optical parametric amplifiers (OPAs), on a beam splitter. With a single pass through OPA, in which a periodically poled lithium niobate waveguide is used as a nonlinear material, the noise reduction of 3.4 +/- 0.2 dB below the shot noise limit is observed with a bandwidth of more than 200 MHz. The entanglement correlation or EPR correlation is confirmed with a sufficient criterion <Delta(2)(X-a+X-b)>+<Delta(2)(Y-a-Y-b)>=1.28 < 2.
  • Yun Zhang, Tatsuya Furuta, Ryuhi Okubo, Kosuke Takahashi, Takuya Hirano
    PHYSICAL REVIEW A, 76(1) 012314, Jul, 2007  
    We report on the generation of broadband pulsed quadrature entanglement by combining two squeezed vacua, which are generated from two degenerate optical parametric amplifiers (OPAs), on a beam splitter. With a single pass through OPA, in which a periodically poled lithium niobate waveguide is used as a nonlinear material, the noise reduction of 3.4 +/- 0.2 dB below the shot noise limit is observed with a bandwidth of more than 200 MHz. The entanglement correlation or EPR correlation is confirmed with a sufficient criterion <Delta(2)(X-a+X-b)>+<Delta(2)(Y-a-Y-b)>=1.28 < 2.
  • 平野 琢也
    日本物理學會誌, 62(6) 446-446, Jun 5, 2007  
  • Yujiro Eto, Takashi Tajima, Yun Zhang, Takuya Hirano
    OPTICS LETTERS, 32(12) 1698-1700, Jun, 2007  
    Squeezed light was generated at a telecommunication wavelength via single-pass optical parametric amplification in a periodically poled Mg-O-doped LiNbO3 waveguide. Classical parametric deamplification of -8.9 dB was achieved. This large magnitude of deamplification indicates that the problem of gain-induced diffraction was avoided by employing the waveguide. Squeezing of 3.2 dB was directly observed using a time-domain pulsed homodyne detector. (C) 2007 Optical Society of America
  • Yujiro Eto, Takashi Tajima, Yun Zhang, Takuya Hirano
    OPTICS LETTERS, 32(12) 1698-1700, Jun, 2007  
    Squeezed light was generated at a telecommunication wavelength via single-pass optical parametric amplification in a periodically poled Mg-O-doped LiNbO3 waveguide. Classical parametric deamplification of -8.9 dB was achieved. This large magnitude of deamplification indicates that the problem of gain-induced diffraction was avoided by employing the waveguide. Squeezing of 3.2 dB was directly observed using a time-domain pulsed homodyne detector. (C) 2007 Optical Society of America
  • Zhang Y, Furuta T, Okubo R, Hirano T
    Meeting abstracts of the Physical Society of Japan, 62(1) 170-170, Feb 28, 2007  
  • Okubo R, Furuta T, Zhang T, Hirano T
    Meeting abstracts of the Physical Society of Japan, 62(1) 170-170, Feb 28, 2007  
  • Eto Y, Tajima T, Zhang Y, Hirano T
    Meeting abstracts of the Physical Society of Japan, 62(1) 169-169, Feb 28, 2007  
  • Furuta T, Ookubo R, Zhang Yung, Hirano T
    Meeting abstracts of the Physical Society of Japan, 62(1) 169-169, Feb 28, 2007  
  • Matsuda Tomohide, Hirano Takuya
    Meeting abstracts of the Physical Society of Japan, 62(1) 169-169, Feb 28, 2007  
  • Tomiyama A, Iwata M, Kuwamoto T, Tojo S, Hirano T
    Meeting abstracts of the Physical Society of Japan, 62(1) 157-157, Feb 28, 2007  
  • Iwata M, Hamasaki K, Tojo S, Kuwamoto T, Hirano T
    Meeting abstracts of the Physical Society of Japan, 62(1) 157-157, Feb 28, 2007  
  • Shingo Tokunaga, Kazuya Shirasaki, Takuya Hirano
    Conference on Lasers and Electro-Optics Europe - Technical Digest, 62(1), 2007  

Books and Other Publications

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Professional Memberships

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Works

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Research Projects

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Industrial Property Rights

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