理学学士, 中国　山西大学

理学修士, 中国　山西大学

理学博士, 中国　山西大学

量子光学 量子情報 レーザー分光

量子光学 量子情報 レーザー分

自然科学一般, 半導体、光物性、原子物理

ナノテク・材料, 光工学、光量子科学

2021年04月01日
電気通信大学, 教授

2013年07月01日 - 2021年03月31日
電気通信大学, 准教授

2008年04月01日 - 2013年06月30日
電気通信大学, 助教

2008年04月01日
電気通信大学, 助教 准教授

2006年03月01日 - 2008年03月31日
学習院大学, 客員研究員

2006年03月01日 - 2008年03月31日
日本科学技術研究機構, 研究員

2001年05月07日 - 2006年02月28日
情報通信研究機構, 専攻研究員

2000年05月07日 - 2001年03月31日
産業総合研究所, 計量標準総合センター, AIST フェロー

2017年01月01日
editorial board, scientific reports

Accessing the spectrum of a single-photon by the Hong-Ou-Mandel interference
Lifeng Duan; Aojie Xu; Lirong Wang; Yun Zhang
Optics Express, 32巻, 4号, 掲載ページ 5418-5428, 出版日 2024年01月

Spectral Characterization of Two-Photon Interference between Independent Sources
Duan, Lifeng; Aojie Xu; Yun Zhang
photonics, 10巻, 10号, 掲載ページ 1125, 出版日 2023年10月

Parallel-to-orthogonal polarisation-state converter for dual-mode Nd:YVO4 microchip laser
Masaharu Hyodo; Yun Zhang; Masayoshi Watanabe; Shingo Saito
Electron. Lett, 57巻, 掲載ページ 802-803, 出版日 2021年07月22日

Measurement of the wavefunction for a biphoton state with homodyne detection using least squares estimation
Yashui Han; Daohua Wu; Katauyuki Kasai; Masayoshi Watanabe; Yun Zhang
J. Opt., 22巻, 掲載ページ 025202, 出版日 2020年02月01日

Controllable electromagnetically induced grating in a cascade-type atomic system
Jin-Peng Yuan; Chao-Hua Wu; Yi-Hong Li; Li-Rong Wang; Yun Zhang; Lian-Tuan Xiao; Suo-Tang Jia
Frontiers of Physics, 14巻, 5号, 掲載ページ 52603, 出版日 2019年09月

Integer and fractional electromagnetically induced Talbot effects in a ladder-type coherent atomic system
Jinpeng Yuan; Chaohua Wu; Yihong Li; Lirong Wang; Yun Zhang; Liantuan Xiao; Suotang Jia
Optics Express, 27巻, 1号, 掲載ページ 92-100, 出版日 2019年01月08日

Multi-photon interference between a two-photon state and a weak coherent state
Yun Zhang; Lirong Wang; Masayoshi Watanabe
Optics InfoBase Conference Papers, OSA - The Optical Society, 出版日 2018年10月31日, Multi-photon interference between a two-photon state and a weak coherent state is presented. The results show that the interference depended on not only the relative phase but also the amplitude between the two interference fields.

Experimental observation of three-photon interference between a two-photon state and a weak coherent state on a beam splitter
Tingyu Li; Saburo Sakurai; Katuyuki Kasai; Lirong Wang; Masayoshi Watanabe; Yun Zhang
Optics Express, 26巻, 掲載ページ 20442-20449, 出版日 2018年08月26日

Controlling quantum interference in phase space with amplitude
Yinghong Xue; Tingyu Li; Katsuyuki Kasai; Yoshiko Okada-Shudo; Masayoshi Watanabe; Yun Zhang
SCIENTIFIC REPORTS, NATURE PUBLISHING GROUP, 7巻, 掲載ページ 22291-1-22291-6, 出版日 2017年05月, We experimentally show a quantum interference in phase space by interrogating photon number probabilities (n = 2, 3, and 4) of a displaced squeezed state, which is generated by an optical parametric amplifier and whose displacement is controlled by amplitude of injected coherent light. It is found that the probabilities exhibit oscillations of interference effect depending upon the amplitude of the controlling light field. This phenomenon is attributed to quantum interference in phase space and indicates the capability of controlling quantum interference using amplitude. This remarkably contrasts with the oscillations of interference effects being usually controlled by relative phase in classical optics.

Characteristics of pulse width for an enhanced second harmonic generation
Yun Zhang; Masaharu Hyodo; Yoshiko Okada-Shudo; Yun Zhu; Xiaoyang Wang; Yong Zhu; Guiling Wang; Chuangtian Chen; Shuntaro Watanabe; Masayoshi Watanabe
OPTICS COMMUNICATIONS, ELSEVIER SCIENCE BV, 387巻, 掲載ページ 241-244, 出版日 2017年03月, Temporal characteristics of a cavity enhancement second harmonic (SH) generation for picosecond laser pulse are investigated. We experimentally measured pulse width changes that were indued by group velocity mismatching (GVM), SH process, and enhancement cavity. It indicates that the generated pulse width is a combined effect of the GVM and SH process. Meanwhile, the effect of the enhancement cavity can be avoided by controlling its free spectrum range. A interferometric autocorrelator with a KBBF-PCD as nonlinear crystal is also composed and this extends the measurement light wavelength below 410 nm.

Directionally selective motion detection with bacteriorhodopsin patterned sensor
Yoshiko Okada-Shudo; Tokimasa Tanabe; Takayuki Mukai; Katsuyuki Kasai; Yun Zhang; Masayoshi Watanabe
Synthetic Metals, 222巻, 掲載ページ 249-254, 出版日 2016年10月15日

Experimental realization of spatially separated entanglement with continuous variables using laser pulse trains
Yun Zhang; Ryuhi Okubo; Mayumi Hirano; Yujiro Eto; Takuya Hirano
SCIENTIFIC REPORTS, NATURE PUBLISHING GROUP, 5巻, 掲載ページ 13029, 出版日 2015年08月, Spatially separated entanglement is demonstrated by interfering two high-repetition squeezed pulse trains. The entanglement correlation of the quadrature amplitudes between individual pulses is interrogated. It is characterized in terms of the sufficient inseparability criterion with an optimum result of Delta(2) ((X) over cap (A) - (X) over cap (B)) + Delta(2) ((Y) over cap (A) + (Y) over cap (B)) = 2.52 + 0.06 < 4 in the frequency domain and Delta(2) (<(X)over cap>(A) - (X) over cap (B)) + Delta(2) ((Y) over cap (A) + (Y) over cap (B)) = 2.52 +/- 0.04 < 4 in the time domain. The quantum correlation is also observed when the two measurement stations are separated by a physical distance of 4.5 m, which is sufficiently large to demonstrate the space-like separation, after accounting for the measurement time.

KBBF結晶による準連続発生真空紫外コヒーレンス光源開発にむけて
張 贇; 山口 大智; 陳 創天; 渡部 俊太郎; 渡辺 昌良
レーザー研究, 日本レーザー学会, 43巻, 8号, 掲載ページ 542-545, 出版日 2015年08月

Low intensity noise and narrow line-width diode laser light at 540 nm
Lirong Wang; Ryo Tamaki; Katsuyuki Kasai; Yoshiko Okada-Shudo; Masayoshi Watanabe; Yun Zhang
LASER PHYSICS LETTERS, IOP PUBLISHING LTD, 12巻, 5号, 掲載ページ 055802, 出版日 2015年05月, We present a convenient method to generate high quality single-frequency green light at a wavelength of 540 nm. It consists of a noise suppressed external cavity diode laser at a wavelength of 1080 nm by optical filtering and resonant optical feedback, and a frequency doubling of the fundamental light with an a-cut KTP crystal. Highly efficient conversion is realized by type II non-critical phase matching. A stable single-frequency operation with a maximum power of about 20 mW is performed for more than 3 h. Both the intensity noise and line-width reach the level of a monolithic nonplanar ring laser, which is well known for its extraordinarily narrow line-width and extremely low noise among available single-frequency operating lasers.

Generation of tripartite quantum correlation among amplitude-squeezed beams by frequency doubling in a singly resonant cavity
Tingyu Li; Ryohei Mitazaki; Katsuyuki Kasai; Yoshiko Okada-Shudo; Masayoshi Watanabe; Yun Zhang
Physical Review A - Atomic, Molecular, and Optical Physics, American Physical Society, 91巻, 2号, 出版日 2015年02月26日, We present a technique for generation of tripartite quantum-correlated amplitude-squeezed light beams, using frequency doubling in a singly resonant cavity with two output ports. The two-output second-harmonic (SH) beams are both nonlinearly coupled to the common fundamental beam even though they have no direct interaction. The nonlinear coupling produces noise reduction of amplitude for each beam and quantum correlations among three beams. In our first experiment, we measured amplitude squeezing of 0.5, 0.8, and 0.6 dB for the fundamental beam and two output SH beams, respectively. Meanwhile, quantum correlation of 0.6 dB between the two amplitude-squeezed SH beams and quantum anticorrelation of 0.6 and 0.8 dB between the squeezed fundamental beam and each of the SH beams were observed around the range of optimum conversion efficiency. This opens an alternate way to produce tripartite-quantum-correlated systems.

Generation of tripartite quantum correlation among amplitude-squeezed beams by frequency doubling in a singly resonant cavity
Tingyu Li; Ryohei Mitazaki; Katsuyuki Kasai; Yoshiko Okada-Shudo; Masayoshi Watanabe; Yun Zhang
PHYSICAL REVIEW A, AMER PHYSICAL SOC, 91巻, 2号, 掲載ページ 023833, 出版日 2015年02月, We present a technique for generation of tripartite quantum-correlated amplitude-squeezed light beams, using frequency doubling in a singly resonant cavity with two output ports. The two-output second-harmonic (SH) beams are both nonlinearly coupled to the common fundamental beam even though they have no direct interaction. The nonlinear coupling produces noise reduction of amplitude for each beam and quantum correlations among three beams. In our first experiment, we measured amplitude squeezing of 0.5, 0.8, and 0.6 dB for the fundamental beam and two output SH beams, respectively. Meanwhile, quantum correlation of 0.6 dB between the two amplitude-squeezed SH beams and quantum anticorrelation of 0.6 and 0.8 dB between the squeezed fundamental beam and each of the SH beams were observed around the range of optimum conversion efficiency. This opens an alternate way to produce tripartite-quantum-correlated systems.

Generation of quasi-cw deep ultraviolet light below 200 nm by an external cavity with a Brewster-input KBBF prism coupling device
Yun Zhang; Ryota Hoshi; Daichi Yamaguchi; Yoshiko Okada-Shudo; Masayoshi Watanabe; Masaharu Hyodo; Yun Zhu; Xiaoyang Wang; Yong Zhu; Guilin Wang; Chuangtian Chen; Teruto Kanai; Shuntaro Watanabe
Optics Communications, 295巻, 掲載ページ 176-179, 出版日 2013年05月15日, We report the generation of coherent deep ultraviolet light at 199 nm with a maximum average power of 32 mW by frequency quadrupling a picosecond pulse train from a Ti:sapphire laser. Two frequency-doubling stages were taking place in resonant cavities that can enhance conversion efficiency of second harmonic generations (SHGs). To reduce the extra-loss of the resonant cavity, a Brewster-input KBe2BO3F2 (KBBF) prism coupling device (PCD) was designed and employed in the second stage SHG for the first time. © 2013 Elsevier B.V.

Generation of 1.2 W green light using a resonant cavity-enhanced second-harmonic process with a periodically poled KTiOPO4
Yun Zhang; Nobuyuki Hayashi; Hiroshi Matsumori; Ryohei Mitazaki; Yinghong Xue; Yoshiko Okada-Shudo; Masayoshi Watanabe; Katsuyuki Kasai
OPTICS COMMUNICATIONS, ELSEVIER SCIENCE BV, 294巻, 掲載ページ 271-275, 出版日 2013年05月, We report on frequency doubling of a single frequency cw Nd:YAG laser at wavelength of 1064 nm using a periodically poled KTiOPO4 crystal (PPKTP) placed in a single resonant ring enhanced cavity. A maximum output power of 1.23 W, corresponding to 72% of conversion efficiency with 1.7 W of fundamental power, was achieved. This is, to the best of our knowledge, the highest power obtained at this wavelength with PPKTP crystal in an external enhanced cavity. The output power is continuously stable with a peak to peak fluctuation of less than 1% over 4 h owing to optimum design of an enhanced cavity; moreover, the setup is inherently simple and robust. Therefore, it is suitable to be a light source for quantum optics experiments. (C) 2012 Elsevier B.V. All rights reserved.

Temporal Characteristics of Pulsed Squeezing in a Nonlinear Optical Waveguide
Yujiro Eto; Akane Koshio; Akito Ohshiro; Yun Zhang; Masahide Sasaki; Takuya Hirano
JAPANESE JOURNAL OF APPLIED PHYSICS, JAPAN SOC APPLIED PHYSICS, 52巻, 4号, 出版日 2013年04月, We experimentally investigate the temporal characteristics of picosecond squeezed pulses generated via an optical parametric amplification in a periodically poled MgO:LiNbO3 waveguide. The noise variances for the various time delays between the squeezed pulse and a local oscillator are measured using a balanced homodyne detector. The measured delay dependence is asymmetric, and this asymmetry indicates that the phase chirping of the squeezed pulse is different from that of the local oscillator pulse. We show that the observed squeezing can be improved by using the pulse shaping of the local oscillator. (C) 2013 The Japan Society of Applied Physics

Efficient phase noise suppression of an external-cavity diode-laser by optical filtering and resonant optical feedback
Yun Zhang; S. Miyakawa; K. Kasai; Y. Okada-Shudo; M. Watanabe
Appl. Phys. B, 108巻, 掲載ページ 39-42, 出版日 2012年08月

Generation of Quasi-CW Deep Ultraviolet Light below 200 nm by Two Successive Cavity Enhanced Second Harmonic Generators
Yun Zhang; Nobuyoshi Watanabe; Yoshiko Okada-Shudo; Masayoshi Watanabe; Masaharu Hyodo; Xiaoyang Wang; Yong Zhu; Chuangtian Chen; Teruto Kanai; Shuntaro Watanabe
JAPANESE JOURNAL OF APPLIED PHYSICS, JAPAN SOC APPLIED PHYSICS, 50巻, 4号, 掲載ページ 042703, 出版日 2011年04月, By frequency quadrupling a picosecond pulse train from a Ti:sapphire laser with a wavelength of 798 nm and a repetition rate of 82 MHz, we generated a coherent deep ultraviolet light below 200 nm. Two frequency-doubling stages take place in resonant cavities that can increase conversion efficiency. This allows an overall efficiency of 4.3% and produces an output power of up to 60 mW. In the second stage, in which a KBe2BO3F2 (KBBF) crystal was employed as a nonlinear medium, conversion efficiency is increased by about three times compared with that of the single-pass configuration. Taking into account reflective loss, conversion efficiency is improved five times. (C) 2011 The Japan Society of Applied Physics

Transporting continuous quantum variables of individual light pulses
Yujiro Eto; Yun Zhang; Takuya Hirano
OPTICS EXPRESS, OPTICAL SOC AMER, 19巻, 2号, 掲載ページ 1360-1366, 出版日 2011年01月, 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

Stable generation of quadrature entanglement using a ring interferometer
Yujiro Eto; Akihiro Nonaka; Yun Zhang; Takuya Hirano
PHYSICAL REVIEW A, AMER PHYSICAL SOC, 79巻, 5号, 掲載ページ 050302(R), 出版日 2009年05月, 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.

Generation of quasi-continuous-wave vacuum-ultraviolet coherent light by fourth-harmonic of a Ti:sapphire laser with KBBF crystal
Yun Zhang; Yusuke Sato; Nobuyoshi Watanabe; Riskey Ananda; Yoshiko Okada-Shudo; Masayoshi Watanabe; Masaharu Hyodo; Xiaoyang Wang; Chuangtian Chen; Teruto Kanai; Shuntaro Watanabe
OPTICS EXPRESS, OPTICAL SOC AMER, 17巻, 10号, 掲載ページ 8119-8124, 出版日 2009年05月, We report the generation of quasi-continuous-wave vacuum-ultraviolet (VUV) coherent light based on a Ti:sapphire laser with two successive frequency doubling stages. In the first stage, UV light at 399 nm with power of 1.1 W was obtained by exploiting an enhanced cavity. With a KBBF crystal as nonlinear material, quasi-continuous-wave VUV coherent light with power of about 25 mW at 199.5 nm and 4.7 mW at 193.5 nm were achieved through a single-pass SHG configuration, respectively, in the second stage. (C) 2009 Optical Society of America

Measurement of Entanglement in Time Domain - an Experiment towards Demonstration of EPR paradox with Continuous Variable using Laser Pulses
Yun Zhang; R. Okubo; M. Hirano; T. Hirano
QUANTUM COMMUNICATION, MEASUREMENT AND COMPUTING (QCMC), AMER INST PHYSICS, 1110巻, 掲載ページ 197-+, 出版日 2009年, We report on a measurement of entanglement in the time domain. The entanglement is examined by the Duan-Simon criteria. We obtained Duan-Simon criteria of Delta(2)(x(1) - x(2)) + Delta(2)(p(1) + p(2)) = 1.4 < 2 without optimal gain and Delta(2)(x(1) - x(2)) + Delta(2)(p(1) + p(2)) = 1.2 < 2 with optimal gain, respectively. This opens the way to realize both efficient and truly causal EPR paradox.

Pulsed homodyne detection of quadrature entanglement at telecommunication wavelength
Yujiro Eto; Akihiro Nonaka; Yun Zhang; Takuya Hirano
QUANTUM COMMUNICATION, MEASUREMENT AND COMPUTING (QCMC), AMER INST PHYSICS, 1110巻, 掲載ページ 181-+, 出版日 2009年, We report on the generation of quadrature entangled light pulses at the telecommunication wavelength of 1.535 mu m by combining two squeezed pulses. The quadrature phase amplitudes of the entangled light pulses are measured by using two time-domain pulsed homodyne detectors, which yield one pair of measurement values by single-shot measurement for each pulse. The entanglement is confirmed with a sufficient criterion <Delta[ (x) over cap (a) + (x) over cap (b)](2)> + <Delta[ (p) over cap (a) - (p) over cap (b)](2)> = 0.64 < 1.

Time-resolved pulsed homodyne detector and its application to measurement of pulsed squeezed states
Ryuhi Okubo; Mayumi Hirano; Yun Zhang; Takuya Hirano
QUANTUM COMMUNICATION, MEASUREMENT AND COMPUTING (QCMC), AMER INST PHYSICS, 1110巻, 掲載ページ 169-+, 出版日 2009年, We report a pulsed homodyne detector that operates in the time domain and can measure individual pulses at a repetition rate of 76 MHz. The individuality of the measurement is interrogated by correlation coefficient between adjacent pulses. The homodyne detector is composed of a low-noise high-speed operational amplifier. We observed 2.3 dB of squeezing in both the time and frequency domains.

Observation of squeezed light at 1.535 μm using a pulsed homodyne detector
Yujiro Eto; Takashi Tajima; Yun Zhang; Takuya Hirano
Opt. Express, 16巻, 掲載ページ 10650, 出版日 2008年07月

Pulse resolved measurement of quadrature phase amplitudes of squeezed pulse train at 76 MHz repetition rate
Ryuhi Okubo; Mayumi Hirano; Yun Zhang; Takuya Hirano
Opt. Lett., 33巻, 掲載ページ 843, 出版日 2008年07月

Generation of non-classical states from an optical parametric oscillator/amplifier and their applications
Yun Zhang
FRONTIERS OF PHYSICS IN CHINA, HIGHER EDUCATION PRESS, 3巻, 2号, 掲載ページ 126-152, 出版日 2008年06月, Quantum information and quantum optics are rapidly advancing areas of modern physics. As an important device in quantum optics and quantum information, the optical parametric amplifier/oscillator (OPA/O) has been extensively studied and applied to the generation of non- classical state since the 1980s. This article reviews the progress in the generation of nonclassical state from an OPO/A and application of twin beams in quantum optics and quantum information.

Experimental generation of broadband quadrature entanglement using laser pulses
Yun Zhang; Tatsuya Furuta; Ryuhi Okubo; Kosuke Takahashi; Takuya Hirano
PHYSICAL REVIEW A, AMER PHYSICAL SOC, 76巻, 1号, 掲載ページ 012314, 出版日 2007年07月, 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.

Observation of squeezed light at 1.535 μm using a pulsed homodyne detector
Yujiro Eto; Takashi Tajima; Yun Zhang; Takuya Hirano
Opt. Lett., OPTICAL SOC AMER, 32巻, 12号, 掲載ページ 1698-1700, 出版日 2007年06月, 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

Efficient noise suppression of an amplified diode-laser by optical filtering and resonant optical feedback
Y. Zhang; K. Hayasaka; K. Kasai
APPLIED PHYSICS B-LASERS AND OPTICS, SPRINGER, 86巻, 4号, 掲載ページ 643-646, 出版日 2007年03月, We present the noise suppression of an amplified diode laser by using an optical filter and resonant optical feedback. The intensity noise of the amplified diode laser has been significantly decreased by using the optical filter cavity. It was further suppressed and reached the shot noise limit at 15 MHz by introducing resonant optical feedback from the transmission of the filter cavity. The filter cavity transmits 53% of injection power, and the output power of the filter cavity is more than 200 mW. The observed frequency fluctuations were less than 100 kHz in one minute. This level of noise suppression and output power may allow diode lasers to be utilized in many quantum-optics experiments.

Experimental generation of broadband quadrature entanglement using laser pulses
Yun Zhang; Ryuhi Okubo; Tatsuya Furuta; Takuya Hirano
Optics InfoBase Conference Papers, Optical Society of America (OSA), 出版日 2007年, We report the generation of broadband pulsed quadrature entanglement by combing two squeezed vacua with squeezing of 3.4±0.2 dB and bandwidth of 200 MHz, which are generated from two degenerate optical parametric amplifiers. © 2007 Optical Society of America.

Pulsed homodyne detection of squeezed light at telecommunication wavelength
Yujiro Eto; Tajima Takashi; Yun Zhang; Takuya Hirano
Optics InfoBase Conference Papers, Optical Society of America (OSA), 出版日 2007年, We present the generation of squeezed light at 1.535 μm by single-pass optical parametric amplification in a periodically poled MgO-doped LiNbO3 waveguide. Squeezing of-4.2 dB was observed by using a temporally matched local oscillator. © 2007 Optical Society of America.

Generation of two-mode bright squeezed light using a noise-suppressed amplified diode laser
Yun Zhang; Kazuhiro Hayasaka; Katsuyuki Kasai
OPTICS EXPRESS, OPTICAL SOC AMER, 14巻, 26号, 掲載ページ 13083-13088, 出版日 2006年12月, We present the generation of nonclassical state using an amplified diode laser as a light source. The intensity noise of an amplified diode laser was significantly suppressed and reached the shot noise limit at 15 MHz using both a filter cavity and resonant optical feedback. Frequency doubling efficiency of 66% and up to 120 mW output power of green has been achieved in cw second-harmonic generation from 1080 nm to 540 nm. Bright two-mode amplitude-squeezed state was generated from a type-II nondegenerate optical parametric amplifier pumped by generated green light. The measured noise reduction is 2.1 +/- 0.2 dB below the shot-noise level. (c) 2006 Optical Society of America.

Realization of quantum correlation transfer between twin beams by conditional preparation technique
Yun Zhang; Kazuhiro Hayasaka; Katsuyuki Kasai
OPTICS COMMUNICATIONS, ELSEVIER SCIENCE BV, 266巻, 2号, 掲載ページ 598-603, 出版日 2006年10月, A conditional quantum correlation transfer is demonstrated experimentally for continuous variables by employing two pairs of twin-beams states. In present paper, the quantum correlation of twin beams is indicated by loss coefficient or "gemellity", which is the remaining noise on the intensity difference normalized to the shot noise level. The quantum correlation between two initial idler beams with loss coefficient of 0.4 was conditionally transferred from two pairs of initially independent twin beams with loss coefficient of 0.2. A theory of conditional quantum correlation transfer and comparison between experimental results and theoretical prediction are also presented. The experimental results agree with the theory well. (c) 2006 Elsevier B.V. All rights reserved.

Pulsed homodyne detection of squeezed light at telecommunication wavelength
Yujiro Eto; Takashi Tajima; Yun Zhang; Takuya Hirano
JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS, INST PURE APPLIED PHYSICS, 45巻, 29-32号, 掲載ページ L821-L823, 出版日 2006年08月, We present the generation of pulsed squeezed light at telecommunication wavelength of 1.535 mu m via single-pass parametric amplification in a periodically poled MgO-doped lithium niobate waveguide using a novel collinear configuration. The quadrature-amplitude of squeezed light is measured in time domain. The classical parametric deamplification of -3.2 dB and quadrature squeezing of -1.5 dB are observed. The maximum classical parametric amplification of 19.3 dB is obtained at pump average power of 0.47 mW, taking advantage of the tight confinement in a waveguide and high peak power of the pulsed light.

Conditional generation of twin sub-Poissonian beams via post-selection
Yun Zhang; Kazuhiro Hayasaka; Katsuyuki Kasai
International Journal of Modern Physics B, 20巻, 11-13号, 掲載ページ 1564-1569, 出版日 2006年05月20日, We report the experimental demonstration of generation of twin sub-Poissonian beams by using a conditional preparation technique. By this simple technique, we generate twin sub-Poissonian beams with a quantum correlation of 4.0 ± 0.2 dB between two sub-Poissonian beams of 4.0 ± 0.3 dB noise reductions from two sets of initially independent twin beams, each characterized by intensity-difference squeezing of 7.0 ± 0.3 dB. © World Scientific Publishing Company.

Experimental realization of quantum correlation transfer
Yun Zhang; Katsuyuki Kasai; Kazuhiro Hayasaka
Optics Commun., 266巻, 掲載ページ 598, 出版日 2006年

Conditional generation of twin sub-Possionian states
Yun Zhang; Katsuyuki Kasai; Kazuhiro Hayasaka
International Journal of Modern Physics B, 20巻, 掲載ページ 1546, 出版日 2006年

Experimental characterization of quantum-correlated twin beams and a quantum channel with twin beams
Y Zhang; K Hayasaka; K Kasai
OPTICS AND SPECTROSCOPY, OPTICAL SOC AMER, 99巻, 2号, 掲載ページ 181-184, 出版日 2005年08月, We report the generation and characterization of quantum-correlated twin beams and their application to a quantum channel. Compared with our previous results, the characterization of twin beams and the quantum channel have been studied with 7.0-dB intensity difference squeezing. The measured inference variance of twin beams is decreased to 0.40 +/- 0.02. For the quantum channel, the bit error rate will be 0.035 by using 7.0-dB intensity difference squeezing compared with our previous result of 0.067 by using 4.9-dB intensity difference squeezing. (c) 2005 Pleiades Publishing, Inc.

Conditional transfer of quantum correlation in the intensity of twin beams
Yun Zhang; Kazuhiro Hayasaka; Katsuyuki Kasai
Physical Review A - Atomic, Molecular, and Optical Physics, 71巻, 6号, 出版日 2005年06月, A conditional protocol of transferring quantum correlations in a continuous variable regime was experimentally demonstrated. The quantum correlation in two pairs of twin beams, each characterized by intensity-difference squeezing of 7.0±0.3dB, was transferred to two initially independent idler beams. The quantum-correlation transfer resulted in intensity-difference squeezing of 4.0±0.2dB between two idler beams. The dependence of the preparation probability and transfer fidelity on the selection bandwidth was also studied. © 2005 The American Physical Society.

Conditional transfer of quantum correlation in the intensity of twin beams
Y Zhang; K Hayasaka; K Kasai
PHYSICAL REVIEW A, AMER PHYSICAL SOC, 71巻, 6号, 掲載ページ 062341, 出版日 2005年06月, A conditional protocol of transferring quantum correlations in a continuous variable regime was experimentally demonstrated. The quantum correlation in two pairs of twin beams, each characterized by intensity-difference squeezing of 7.0 +/- 0.3 dB, was transferred to two initially independent idler beams. The quantum-correlation transfer resulted in intensity-difference squeezing of 4.0 +/- 0.2 dB between two idler beams. The dependence of the preparation probability and transfer fidelity on the selection bandwidth was also studied.

Conditional generation of twin sub-Possionian states
Yun Zhang; Kazuhiro Hayasaka; Katsuyuki Kasai
Quantum Electronics and Laser Science Conference (QELS), 2巻, 掲載ページ 1124-1126, 出版日 2005年, We conditionally generated quantum correlated sub-Possionian states with quantum correlation of 4.0±0.2 dB between a pair of sub-Possionian states, which is exhibiting noise reduction of 4.0±0.3 dB in intensity. © 2005 Optical Society of America.

Nonclassical light generation from an optical parametric oscillator pumped by a frequency-doubled diode laser
Kazuhiro Hayasaka; Yun Zhang; Katsuyuki Kasai
Proceedings of SPIE - The International Society for Optical Engineering, 5631巻, 掲載ページ 143-150, 出版日 2005年, Quantum-correlated twin beams were successfully generated from an optical parametric oscillator (OPO) pumped by a frequency-doubled diode laser. The 50-mW diode laser output at 1080 nm was first converted to 22.5-mW green light, and then was used to pump an OPO to yield signal and idler beams with a total power of 5 mW. Noise reduction of 4.3 dB below the shot-noise level was observed in the intensity-difference spectrum. The setup opens a simple way to a compact and low-cost source of diverse nonclassical states of light.

Generation of 22.8 mW single-frequency green light by frequency doubling of a 50-mW diode laser
K Hayasaka; Y Zhang; K Kasai
OPTICS EXPRESS, OPTICAL SOC AMER, 12巻, 15号, 掲載ページ 3567-3572, 出版日 2004年07月, We report frequency doubling of an extended-cavity diode laser in an a-cut KTP crystal. Continuous-wave, single-mode green light at 540 nm with a power of 22.8 mW was generated from an input of 44.2 mW by type II non-critical phase matching. Stable operation with intensity fluctuations smaller than 1% peak-to-peak for more than two hours was achieved by employing resonant optical feedback. The optical feedback also reduced the fundamental-wave linewidth to the upper limit of 41 kHz. (C) 2004 Optical Society of America.

Generation of twin beams from an optical parametric oscillator pumped by a frequency-doubled diode laser
K Hayasaka; Y Zhang; K Kasai
OPTICS LETTERS, OPTICAL SOC AMER, 29巻, 14号, 掲載ページ 1665-1667, 出版日 2004年07月, Quantum-correlated twin beams were generated from a triply resonant optical parametric oscillator with an a-cut KTP crystal pumped by a frequency-doubled diode laser. A total output of 5.1 mW was obtained in the classical-nonclassical light-conversion system driven by a 50-mW diode laser at 1080 nm. A quantum-noise reduction of 4.3 dB (63%) in the intensity difference between the twin beams was successfully observed at the detection frequency of 3 MHz. (C) 2004 Optical Society of America.

Frequency reproducibility of an iodine-stabilized Nd : YAG laser at 532 nm
FL Hong; J Ishikawa; Y Zhang; RX Guo; A Onae; H Matsumoto
OPTICS COMMUNICATIONS, ELSEVIER SCIENCE BV, 235巻, 4-6号, 掲載ページ 377-385, 出版日 2004年05月, We have established an ensemble of iodine-stabilized Nd:YAG lasers to verify the frequency reproducibility of the laser. The stability, repeatability and several systematic shifts of the laser frequency are investigated by heterodyne beating of the lasers. The frequency dispersion of the ensemble of lasers is evaluated to be 0.5 kHz (corresponding to a relative frequency uncertainty of 8 x 10(-13)). The absolute frequency of one of the lasers (named as Y3) is measured to be 563 260 223 507 897(58) Hz using a femtosecond optical comb, when the laser was stabilized on the a(10) component of the R(56)32-0 transition of I-127(2) for a cold-finger temperature of -10 degreesC. This group of lasers, including one transportable laser, forms an ensemble of optical frequency standards, which serves for many applications such as international comparisons, optical frequency measurements, frequency calibration services and high-resolution spectroscopy. (C) 2004 Elsevier B.V. All rights reserved.

Single-beam noise characteristics of quantum-correlated twin beams
Y Zhang; K Kasai; K Hayasaka
JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS, OPTICAL SOC AMER, 21巻, 5号, 掲載ページ 1044-1049, 出版日 2004年05月, We investigated the intensity noise spectra of a single beam of a pump-enhanced continuous-wave optical parametric oscillator (OPO), which was used to generate quantum-correlated twin beams, as a function of the pump power. With a triply (pump-, signal-, and idler-) resonant cavity, the oscillation threshold of our OPO was 8.5 +/- 1.3 mW and the measured slope conversion efficiency was 0.72 +/- 0.02. Twin beams with a power of 240 mW were generated at a pump power of 350 mW The relaxation oscillation frequencies, which depend on the pump power, were observed when the pump power of the OPO was 12.5-28 mW The experimental results confirm the predicted increase in OPO relaxation frequency with pump power. We experimentally inferred squeezing of the single-beam intensity, for the first time to our knowledge, by exploiting the nature of quantum noise that is dependent on loss. (C) 2004 Optical Society of America.

Quantum channel using photon number correlated twin beams
Y Zhang; K Kasai; K Hayasaka
OPTICS EXPRESS, OPTICAL SOC AMER, 11巻, 26号, 掲載ページ 3592-3597, 出版日 2003年12月, We report quantum communications channel using photon number correlated twin beams. The twin beams are generated from a nondegenerate optical parametric oscillator, and the photon number difference is used to encode the signal. The bit error rate of our system will be 0.067 by using the twin beams comparing with 0.217 by using the coherent state as the signal carrier. (C) 2003 Optical Society of America.

Joint probability and conditional distribution of twin beams
Yun Zhang; Katsuyuki Kasai
2003 European Quantum Electronics Conference, EQEC 2003, Institute of Electrical and Electronics Engineers Inc., 掲載ページ 380, 出版日 2003年, Joint probability and conditional distribution of twin beams generated by an optical parametric oscillator is reported. We select the photon number fluctuation (intensity fluctuation) as our measured variable. In direct detection with a photodetector, given the high detection efficiency, the photocurrent fluctuation is corresponding to the photon number fluctuation.

Experimental investigation of the intensity fluctuation joint probability and conditional distributions of the twin-beam quantum state
Yun Zhang; Katsuyuki Kasai; Masayoshi Watanabe
Optics Express, Optical Society of America (OSA), 11巻, 1号, 掲載ページ 14-19, 出版日 2003年, We give the intensity fluctuation joint probability of the twin-beam quantum state, which was generated with an optical parametric oscillator operating above threshold. Then we present what to our knowledge is the first measurement of the intensity fluctuation conditional probability distributions of twin beams. The measured inference variance of twin beams 0.62±0.02, which is less than the standard quantum limit of unity, indicates inference with a precision better than that of separable states. The measured photocurrent variance exhibits a quantum correlation of as much as -4.9±0.2 dB between the signal and the idler. © 2003 Optical Society of America.

Experimental investigation of the correlation and inference of the twin-beam quantum state
Yun Zhang; Katsuyuki Kasai; Masayoshi Watanabe
Optics Express, 11巻, 掲載ページ 14, 出版日 2003年

Hyperfine structure and absolute frequency determination of the R(121)35-0 and P(142)37-0 transitions of I-127(2) near 532 nm
FL Hong; Y Zhang; J Ishikawa; A Onae; H Matsumoto
OPTICS COMMUNICATIONS, ELSEVIER SCIENCE BV, 212巻, 1-3号, 掲載ページ 89-95, 出版日 2002年10月, Hyperfine structures of the R(1 2 1)35-0 and P(1 4 2)37-0 transitions of molecular iodine at the blue end of the tuning range of a frequency-doubled Nd:YAG laser are measured by using two I-2-stabilized lasers. The absolute 4 frequencies of the observed transitions are determined by a frequency link to an optical frequency reference (the R(5 6)32-0:a(10) hyperfine transition), using an optical frequency comb generator. The observed hyperfine transitions are good frequency references for both frequency-doubled Nd:YAG and Nd:YVO4 lasers in the 532 nm region. High-accurate hyperfine constants are obtained for the P(I 4 2)37-0 transition by fitting the measured hyperfine splittings to a four-term Hamiltonian, which includes the electric quadrupole, spin-rotation, tensor spin-spin, and scalar spin-spin interactions. (C) 2002 Elsevier Science B.V. All rights reserved.

Investigation of the photon-number statistics of twin beams by direct detection
Y Zhang; K Kasai; M Watanabe
OPTICS LETTERS, OPTICAL SOC AMER, 27巻, 14号, 掲載ページ 1244-1246, 出版日 2002年07月, We present the results of an experiment in which we observed photon-number statistics of twin beams emerging from a nondegenerate optical parametric oscillator. We generated the photocurrent for recording by detecting the light and mixing it with a standard electrical oscillator. The measured photocurrent variances exhibited a quantum correlation of as much as -4.9 dB between signal and idler, whereas their photon number distributions were super-Poissonian. We also obtained the difference photon-number distribution. (C) 2002 Optical Society of America.

Vibration dependence of the tensor spin-spin and scalar spin-spin hyperfine interactions by precision measurement of hyperfine structures of I-127(2) near 532 nm
FL Hong; Y Zhang; J Ishikawa; A Onae; H Matsumoto
JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS, OPTICAL SOC AMER, 19巻, 5号, 掲載ページ 946-953, 出版日 2002年05月, Hyperfine structures of the R(87)33-0, R(145)37-0, and P(132)36-0 transitions of molecular iodine near 532 nm are measured by observing the heterodyne beat-note signal of two I-2-stabilized lasers, whose frequencies are bridged by an optical frequency comb generator. The measured hyperfine splittings are fit to a four-term Hamiltonian, which includes the electric quadrupole, spin-rotation, tensor spin-spin, and scalar spin-spin interactions, with an accuracy of similar to720 Hz. High-accurate hyperfine constants are obtained from this fit. Vibration dependences of the tensor spin-spin and scalar spin-spin hyperfine constants are determined for molecular iodine, for the first time to our knowledge. The observed hyperfine transitions are good optical frequency references in the 532-nm region. (C) 2002 Optical Society of America.

Classical and quantum properties of optical parametric amplifier/deamplifier
Y Zhang; K Kasai; M Watanabe
PHYSICS LETTERS A, ELSEVIER SCIENCE BV, 297巻, 1-2号, 掲載ページ 29-36, 出版日 2002年05月, The classical gain and the variances of coupled, signal and idler modes of output from continuous nondegenerate optical parametric amplifier are theoretically analyzed under parametric amplification and deamplification conditions. The correlation between the signal and idler modes is also discussed. The results provide design references for nonclassical light generation systems. (C) 2002 Elsevier Science B.V. All rights reserved.

Quantum switch teleportation with continuous variables using two-mode squeezed state
Yun Zhang; Katsuyuki Kasai; Masayoshi Watanabe
European Journal Physics D 21, 361 (2002), 21巻, 掲載ページ 361, 出版日 2002年

Accurate frequency atlas of molecular iodine near 532 nm measured by an optical frequency comb generator
Y Zhang; J Ishikawa; FL Hong
OPTICS COMMUNICATIONS, ELSEVIER SCIENCE BV, 200巻, 1-6号, 掲載ページ 209-215, 出版日 2001年12月, An optical frequency comb generator (OFCG) at 1064 nm. with a modulation frequency of 2 GHz is developed for an accurate optical frequency link between iodine absorption lines near 532 nm. With the OFCG, we have measured frequency differences between seventeen I-121(2) transitions with a measurement uncertainty of about 240 Hz (relatively 4.3 x 10(-13)), which is mainly contributed from the frequency repeatability of iodine-stabilized Nd:YAG lasers. The measured transitions provide an attractive frequency reference network and are excellent candidates for the practical realization of the meter. (C) 2001 Elsevier Science B.V. All rights reserved.

Gauge block interferometer using three frequency-stabilized lasers
Y Bitou; A Hirai; H Yoshimori; FL Hong; Y Zhang; A Onae; K Seta
RECENT DEVELOPMENTS IN TRACEABLE DIMENSIONAL MEASUREMENTS, SPIE-INT SOC OPTICAL ENGINEERING, 4401巻, 掲載ページ 288-297, 出版日 2001年, We have developed a gauge block measurement system that uses three frequency-stabilized lasers. The stabilized lasers are as follows: an I-2-stabilized offset locked He-Ne laser (633 nm), an I-2-stabilized Nd:YAG laser (532 nm), and a Rb-stabilized diode laser (780 nm). The I2-stabilized offset locked He-Ne laser is commercially available (Nihonkagaku Engineering Co., Ltd.) and its relative wavelength uncertainty is 2.5 x 10(-11). An I-2-stabilized Nd:YAG laser and a Rb-stabilized diode laser was developed in our institute and their relative wavelength uncertainties are 5 x 10(-12) and 1 x 10(-9), respectively. In the measurement system, laser beams were introduced to the interferometer using an optical multimode fiber. An interferometric fringe pattern was taken using a CCD camera and the excess fraction parts were calculated from the fringe pattern using the Fourier transform method. The excess fraction part obtained from the Rb-stabilized semiconductor laser was used only to determine the integer part of the fringe order, because the accuracy and stability of the wavelength were not sufficient for the long gauge block measurements. This interferometer can measure gauge blocks of up to 1000 mm long and the standard uncertainty of the interferometer is about 75 nm for a 1000 mm long gauge block.

Frequency reproducibility of I-2-stabilized Nd : YAG lasers
FL Hong; Y Zhang; J Ishikawa; Y Bitou; A Onae; J Yoda; H Matsumoto; K Nakagawa
LASER FREQUENCY STABILIZATION, STANDARDS, MEASUREMENT AND APPLICATIONS, SPIE-INT SOC OPTICAL ENGINEERING, 4269巻, 掲載ページ 143-154, 出版日 2001年, We have established four I-2-stabilized Nd:YAG lasers to verify the frequency reproducibility of the lasers. The observed square root Allan variance of the four lasers was between 1 similar to 4 x 10(-14) depending on the obtained signal-to-noise ratio of the spectra, when the integration time is larger than 300 s. The observed frequency reproducibility of each laser was ranged from 9.1 x 10(-14) similar to 1.5 x 10(-13) (corresponding to frequency uncertainties of +/- 51 similar to 87 Hz). Frequency reproducibility of a group of lasers (four NRLM lasers) has been evaluated to be 8.2 x 10(-13) (corresponding to a frequency uncertainty of +/- 640 Hz). One of the four NRLM lasers is a compact I-2-stabilized Nd:YAG laser which is suitable to be transported to other laboratories for international frequency comparisons. Using this portable laser, we have accomplished frequency comparisons of Nd:YAG lasers between several metrological institutes in different countries. The absolute optical frequencies of the NRLM lasers were determined with an uncertainty of about 1.5 kHz by the frequency comparison between the NRLM and the JILA (formerly the Joint institute for Laboratory of Astrophysics), Boulder, CO.

Experimental Generation of bright squeezed states from Narrowband NOPA
Yun Zhang; Hai Wang; Xiaoying Li; Jietai Jing; Changde XIe; Kunchi Peng
Phys. Rev. A, 62巻, 掲載ページ 023813, 出版日 2000年

Quantum variances and squeezing of output field from NOPA
Y Zhang; H Su; CD Xie; KC Peng
PHYSICS LETTERS A, ELSEVIER SCIENCE BV, 259巻, 3-4号, 掲載ページ 171-177, 出版日 1999年08月, The quadrature phase squeezing of coupled-mode and intensity difference squeezing between signal and idler mode of output field fron; continuous nondegenerate optical parametric amplifier (NOPA) are theoretically analyzed and compared. The calculation results provide design references for nonclassical light generation system. (C) 1999 Published by Elsevier Science B.V. All rights reserved.

Experimental realization of a quantum measurement for intensity difference fluctuation using a beam splitter
H Wang; Y Zhang; Q Pan; H Su; A Porzio; CD Xie; KC Peng
PHYSICAL REVIEW LETTERS, AMER PHYSICAL SOC, 82巻, 7号, 掲載ページ 1414-1417, 出版日 1999年02月, A new quantum measurement scheme of intensity difference fluctuation between two light beams of equal mean intensity is presented. In this system a beam splitter is used as the coupling device and the twin beams with high quantum correlation are injected into its dark port as the input meter wave instead of the usual vacuum field. A measurement satisfying all the quantum nondemolition criteria is experimentally achieved. The measured sum of the transfer coefficients and the conditional variance are, respectively, T-s + T-m = 1.31 and V-s/m = -2.1 dB. [S0031-9007(99)08445-8].

Generation of two-mode quadrature-phase squeezing and intensity-difference squeezing from a cw-NOPO
KC Peng; Q Pan; H Wang; Y Zhang; H Su; CD Xie
APPLIED PHYSICS B-LASERS AND OPTICS, SPRINGER, 66巻, 6号, 掲載ページ 755-758, 出版日 1998年06月, The configuration of a semimonolithic continuous wave nondegenerate optical parametric oscillator (cw-NOPO) consisting of an alpha-cut KTP crystal pumped by an intracavity frequency-doubled and frequency-stabilized Nd:YAP laser is reported. Both two-mode quadrature-phase squeezing of 3.7 dB and intensity-difference squeezing of 7 dB have been generated from the cw-NOPO operating respectively below and above the oscillation threshold through the frequency down-conversion process.

Sub-shot-noise measurement for slight absorption
H Wang; Q Pan; Y Zhang; CY Xue; CD Xie; KC Peng
SCIENCE IN CHINA SERIES A-MATHEMATICS, SCIENCE PRESS, 41巻, 5号, 掲載ページ 534-540, 出版日 1998年05月, Sub-shot-noise measurement for slight absorption is experimentally achieved with the twin beams of quantum correlation. The improvement in signal-to-noise ratio of 2.5 dB relative to the SNL is obtained. The experimental results demonstrate the predictions of the semi-classical theory.

Intracavity frequency-doubled and frequency-stabilized cw ring Nd : YAP laser
Q Pan; TC Zhang; Y Zhang; RN Li; KC Peng; ZG Yu; QM Lu
APPLIED OPTICS, OPTICAL SOC AMER, 37巻, 12号, 掲載ページ 2394-2396, 出版日 1998年04月, A frequency doubled and frequency-stabilized ring Nd:YAP laser with a sin-mirror cavity is demonstrated. This laser satisfies both the thermal insensitivity and optimal frequency-doubling conditions. A second-harmonic output to 1 W at 0.54 mu m is achieved. The intensity fluctuation is less than +/-1.5% and the frequency stability is better than +/-1 MHz (5 min). (C) 1998 Optical Society of America.

Experimental investigation of intensity difference squeezing using Nd:YAP laser as pump source
Q Pan; Y Zhang; TC Zhang; CD Xie; KC Peng
JOURNAL OF PHYSICS D-APPLIED PHYSICS, IOP PUBLISHING LTD, 30巻, 11号, 掲載ページ 1588-1590, 出版日 1997年06月, A strong quantum correlation between twin-beams at 1.08 mu m wavelength was observed. The intensity difference noise of twin-beams, which is generated by a semimonolithic OPO cavity pumped by a frequency-doubled and stabilized Nd:YAP laser, is about 80% (7 dB) below the short noise limit at the measurement frequency of 1.5 MHz. The threshold of the optical parametric oscillator is about 20 mW. The parametric dependence of the quantum correlation is experimentally investigated. The experimental results agree with the theory well.

27pSK-8 事後変位操作によるパルス毎での量子テレポーテーションの実証(27pSK 量子エレクトロニクス(輻射場の量子情報処理,エンタングルメント),領域1(原子・分子,量子エレクトロニクス,放射線物理))
衛藤 雄二郎; 張 贇; 平野 琢也
一般社団法人日本物理学会, 出版日 2009年03月03日, 日本物理学会講演概要集, 64巻, 1号, 掲載ページ 143-143, 1342-8349, 110007370223, AA11439205

27pSK-6 パルス光を用いた連続変数エンタングルメントの時間領域における測定II(27pSK 量子エレクトロニクス(輻射場の量子情報処理,エンタングルメント),領域1(原子・分子,量子エレクトロニクス,放射線物理))
大久保 竜飛; 平野 真弓; 張 贇; 平野 琢也
一般社団法人日本物理学会, 出版日 2009年03月03日, 日本物理学会講演概要集, 64巻, 1号, 掲載ページ 143-143, 1342-8349, 110007370221, AA11439205

22aZA-11 CWモード同期レーザーと光導波路を用いたスクイーズド光の生成(22aZA 量子エレクトロニクス(量子光学),領域1(原子・分子,量子エレクトロニクス,放射線物理))
平野 真弓; 大久保 竜飛; 張 贇; 平野 琢也
一般社団法人日本物理学会, 出版日 2008年08月25日, 日本物理学会講演概要集, 63巻, 2号, 掲載ページ 125-125, 1342-8349, 110006982849, AA11439205

24pQD-4 通信波長帯パルス光源による連続変数エンタングル状態の生成2(量子エレクトロニクス(量子情報),領域1,原子・分子,量子エレクトロニクス,放射線物理)
衛藤 雄二郎; 野中 章裕; 張 贇; 平野 琢也
一般社団法人日本物理学会, 出版日 2008年02月29日, 日本物理学会講演概要集, 63巻, 1号, 掲載ページ 176-176, 1342-8349, 110007196799, AA11439205

Observation of quadrature squeezing in a χ(2) nonlinear waveguide using a temporally shaped local oscillator pulse
Yujiro Eto; Takashi Tajima; Yun Zhang; Takuya Hirano
出版日 2008年, Optics Express, 16巻, 14号, 掲載ページ 10650-16657

Pulse-resolved measurement of quadrature phase amplitudes of squeezed pulse trains at a repetition rate of 76 MHz
Ryuhi Okubo; Mayumi Hirano; Yun Zhang; Takuya Hirano
出版日 2008年, Optics Letters, 33巻, 13号, 掲載ページ 1458, 0146-9592, 80019722488, 18594664

23pRH-8 通信波長帯パルス光源による連続変数エンタングル状態の生成(量子エレクトロニクス(量子光学),領域1,原子・分子,量子エレクトロニクス,放射線物理)
衛藤 雄二郎; 野中 章裕; 張 贇; 平野 琢也
一般社団法人日本物理学会, 出版日 2007年08月21日, 日本物理学会講演概要集, 62巻, 2号, 掲載ページ 192-192, 1342-8349, 110007143333, AA11439205

23pRH-7 パルス光を用いた連続変数エンタングルメントの時間領域における測定(量子エレクトロニクス(量子光学),領域1,原子・分子,量子エレクトロニクス,放射線物理)
大久保 竜飛; 平野 真弓; 張 贇; 平野 琢也
一般社団法人日本物理学会, 出版日 2007年08月21日, 日本物理学会講演概要集, 62巻, 2号, 掲載ページ 191-191, 1342-8349, 110007139082, AA11439205

21aXK-3 高速ホモダイン検出器を用いたスクイーズド光の時間領域測定(量子エレクトロニクス(量子光学),領域1,原子・分子,量子エレクトロニクス,放射線物理)
古田 達也; 大久保 龍飛; 張 贇; 平野 琢也
一般社団法人日本物理学会, 出版日 2007年02月28日, 日本物理学会講演概要集, 62巻, 1号, 掲載ページ 169-169, 1342-8349, 110007193545, AA11439205

21aXK-6 パルス光を用いた連続変数量子もつれの生成(量子エレクトロニクス(量子光学),領域1,原子・分子,量子エレクトロニクス,放射線物理)
張 贇; 古田 達也; 大久保 龍飛; 平野 琢也
一般社団法人日本物理学会, 出版日 2007年02月28日, 日本物理学会講演概要集, 62巻, 1号, 掲載ページ 170-170, 1342-8349, 110007193542, AA11439205

21aXK-4 パルス光スクイージングの時間波形の最適化(量子エレクトロニクス(量子光学),領域1,原子・分子,量子エレクトロニクス,放射線物理)
衛藤 雄二郎; 田島 崇史; 張 贇; 平野 琢也
一般社団法人日本物理学会, 出版日 2007年02月28日, 日本物理学会講演概要集, 62巻, 1号, 掲載ページ 169-169, 1342-8349, 110007193544, AA11439205

21aXK-5 高速ホモダイン検出器によるスクイーズド状態の測定(量子エレクトロニクス(量子光学),領域1,原子・分子,量子エレクトロニクス,放射線物理)
大久保 竜飛; 古田 達也; 張 贇; 平野 琢也
一般社団法人日本物理学会, 出版日 2007年02月28日, 日本物理学会講演概要集, 62巻, 1号, 1342-8349, 110007193543

26pRB-5 通信波長帯スクイーズド光のパルスモードホモダイン検出II(26pRB 量子エレクトロニクス(量子光学),領域1(原子・分子,量子エレクトロニクス,放射線物理))
田島 崇史; 衛藤 雄二郎; 張 贇; 平野 琢也
一般社団法人日本物理学会, 出版日 2006年08月18日, 日本物理学会講演概要集, 61巻, 2号, 掲載ページ 122-122, 1342-8349, 110007183344, AA11439205

量子エレクトニクス
The University of Electro-Communications

量子エレクトニクス
電気通信大学

光エレクトニクス
The University of Electro-Communications

光エレクトニクス
電気通信大学

光・量子エレクトニクス基礎概論
The University of Electro-Communications

光・量子エレクトニクス基礎概論
電気通信大学

卒業輪講
The University of Electro-Communications

卒業輪講
電気通信大学

光エレクトにクス実験第一
The University of Electro-Communications

光エレクトにクス実験第二
電気通信大学

光エレクトにクス実験第二
電気通信大学

インターシップ
The University of Electro-Communications

インターシップ
電気通信大学

光エレクトにクス実験第一
電気通信大学

光エレクトにクス実験第一
電気通信大学

工学基礎数学および演習
The University of Electro-Communications

インターンシップ
電気通信大学

インターンシップ
電気通信大学

光エレクトニクス実験第一
電気通信大学

電気回路演習
電気通信大学

工学基礎数学および演習
電気通信大学

工学基礎数学および演習
電気通信大学

工学基礎数学
電気通信大学

工学基礎数学
The University of Electro-Communications

工学基礎数学
電気通信大学

光エレクトニクス実験第一
The University of Electro-Communications

光エレクトニクス実験第一
電気通信大学

電気回路演習
The University of Electro-Communications

電気回路演習
電気通信大学

米国物理学会

OSA

2波長レーザーを用いる次世代光ファイバ無線のための位相変調技術の開発
兵頭 政春; 張 贇
日本学術振興会, 科学研究費助成事業, 金沢大学, 基盤研究(C), 2つの縦モードで同時に発振する2モード発振マイクロチップレーザの出力光（2つのモード光はともに鉛直方向の直線偏光）を直交偏光状態に変換するため，出力光を長さ17 mmのLiNbO3複屈折性結晶に導入して，偏光子と光スペクトラムアナライザを用いてその透過光の性質を入念に調べた．その結果，一方のモード光を消光させると他方のモード光の透過率は常にほぼ最大になり，2つのモード光がほぼ完全な直交偏光状態に変換されることを確認した．その一方で，それらの偏光状態は結晶の温度変化の影響を強く受け，4.0 rad/℃のレートでドリフトすることが明らかになった．そこで結晶全体を覆うことができるアクリル樹脂製のエアシールドを自作し，その内部にペルチエ素子と熱交換用ヒートシンクを配置し，シールド内部に恒温の空気を循環させることにより，結晶の温度変化が±0.01℃以下になるように負帰還制御を行った．その結果，シールド効率（室温の変化に対する結晶の温度変化の割合）として1/25の性能が得られ，透過光の偏光状態を長時間安定に維持することができるようになった． 結晶の温度を安定化した状態で透過光の偏光状態の波長依存性を測定し，波長の変化に対して偏光状態がほぼ直線的に変化することを確かめ，101 GHｚの周波数差に対するδ値の差がほぼπ/2になることを確認した．さらに，結晶の印加電圧を変化させて出力光の偏光状態を追跡する方法で半波長電圧を測定したところ，2つのモード光の平均として1.68±0.02 kVの値を得た．, 21K04923
研究期間 2021年04月01日 - 2024年03月31日

量子干渉と推定法を用いた光の波動関数を測定する方法に関する研究
研究期間 2021年04月01日 - 2024年03月31日

ホモダイン検出器を用いて光子干渉に関する研究
研究期間 2017年04月01日 - 2020年03月31日

異なる量子状態間の多光子干渉に関する研究
研究期間 2014年04月01日 - 2017年03月31日

高出力真空紫外・極端紫外高調波光源の開発とレーザー光電子分光の確立
渡部 俊太郎; 渡邊 昌良; 張 贇; 岡田 佳子; 周 春; 辛 埴; 小林 洋平; 板谷 治郎; 金井 輝人
日本学術振興会, 科学研究費助成事業, 東京理科大学, 基盤研究(A), CaF2とKBBFの界面を拡散接合法で接着し、プリズムカップルKBBF素子の開発を行い、これを用いた7eV光源では超高分解能光電子分光による超伝導体の研究、8eV光源では 角度分解光電子分光による２次元ブリルアンゾーンの電子状態の測定に供した。高効率大口径透過型グレーティングを開発し、グレーティングの湾曲による回折波面のひずみの解析を行った。このグレーティングを用いて、フェムト多波長レーザーを開発し、1kHzの繰り返しで基本波（800nm）において0,5 TW、２倍波において0.1 TWの出力を得た。またこのレーザーに二重広帯域波長変換法を適用し、４倍波で90 μJ(45 fs)の出力を得た。, 24246022
研究期間 2012年05月31日 - 2015年03月31日

３波共鳴型差動複合共振器制御による高効率ＣＷ光パラメトリック発振器の開発
笠井 克幸; 張 贇
日本学術振興会, 科学研究費助成事業, 独立行政法人情報通信研究機構, 基盤研究(C), 光パラメトリック発振器は、波長可変のコヒーレント光源として様々な分野で有用なデバイスである。CW(連続波）の光パラメトリック発振器においては、安定でチューナブルな発振を低しきい値で得ることは非常に困難である。本研究においては、ポンプ光・シグナル光・アイドラ光が同時に共振する３波共鳴型の差動複合共振器構造と高効率の疑似位相整合結晶(PPKTP)を組み合わせて、波長可変で低発振しきい値のCW光パラメトリック発振器の開発を行った。, 23560051
研究期間 2011年 - 2013年

導電性プラスチックと視覚機能タンパク質を用いたフレキシブル動画センサーの開発
岡田 佳子; 渡辺 昌良; 張 贇; 田中 一男
日本学術振興会, 科学研究費助成事業, 電気通信大学, 基盤研究(C), 本研究は，水溶性ポリマーを用いた導電性プラスチックと，視覚機能タンパク質バクテリオロドプシン(bR)を組み合わせた柔らかい微分応答光センサーを開発し，ロボットビジョンやマシン操作に適用することを目標とした．最初にITOガラスセルの積層による出力増強を図った．さらに受光部の形状やbR成膜配置に異方性をもつ1画素センサーを作製して照射光の走査方向と速度を検出したところ，速く動く物に対して強く応答することがわかった．最後にITOガラスを導電性ポリマーPETに変更したが，導電率と入射光透過率が低く，ITOガラスで得られた出力値には届かなかったが，大面積で曲率をもつセンサー実現の可能性を確認した．, 23560004
研究期間 2011年 - 2013年