66 results on '"Ryosuke Shimizu"'
Search Results
2. Generation of pseudo-sunlight via quantum entangled photons and the interaction with molecules
- Author
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Yuta Fujihashi, Ryosuke Shimizu, and Akihito Ishizaki
- Subjects
Physics ,QC1-999 - Abstract
Light incident upon molecules triggers fundamental processes in diverse systems present in nature. However, under natural conditions such as sunlight illumination, it is impossible to assign known times for photon arrival due to continuous pumping, and therefore the photoinduced processes cannot be easily investigated. In this work, we demonstrate theoretically that the characteristics of sunlight photons, such as photon number statistics and spectral distribution, can be emulated through a quantum entangled photon pair generated with parametric down-conversion (PDC). We show that the average photon number of sunlight in a specific frequency spectrum, e.g., the visible light, can be reconstructed by adjusting the PDC crystal length and pump frequency, and thereby the molecular dynamics induced by the pseudo-sunlight can be investigated. The entanglement time, which is the hallmark of quantum entangled photons, can serve as a control knob to resolve the photon arrival times, enabling investigations on real-time dynamics triggered by pseudo-sunlight photons.
- Published
- 2020
- Full Text
- View/download PDF
3. Electronically Excited Solute Described by RISM Approach Coupled with Multireference Perturbation Theory: Vertical Excitation Energies of Bioimaging Probes
- Author
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Takeshi Yanai, Daisuke Yokogawa, Yuki Kurashige, and Ryosuke Shimizu
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Infrared Rays ,Electronic structure ,Molecular Dynamics Simulation ,010402 general chemistry ,01 natural sciences ,Molecular physics ,Fluorescence ,Spectral line ,0103 physical sciences ,Physics::Chemical Physics ,Physical and Theoretical Chemistry ,Perturbation theory ,Fluorescent Dyes ,Physics ,Molecular Structure ,010304 chemical physics ,Density matrix renormalization group ,Solvation ,Statistical mechanics ,Photochemical Processes ,0104 chemical sciences ,Computer Science Applications ,Solubility ,Excited state ,Solvents ,Quantum Theory ,Excitation - Abstract
For theoretically studying molecules with fluorescence in the near-infrared region, high-accuracy determination of state energy level is required for meaningful analyses since the spectra of interest are of very narrow energy range. In particular, these molecules are in many cases handled in solution; therefore, consideration of the solvation effect is essential upon calculation together with the electronic structure of the excited state. Earlier studies showed that they cannot be described with conventional methods such as PCM-TD-DFT, yielding results far from experimental data. Here, we have developed a new method by combining a solvation theory based on statistical mechanics (RISM) and a multireference perturbation theory (CASPT2) with the extension of the density matrix renormalization group reference states for calculating the photochemical properties of near-infrared molecules and have obtained higher-accuracy prediction.
- Published
- 2018
4. Improved RISM-CASSCF Optimization via State-Average Treatment and Damping for Characterizing Excited Molecules in Solution with Multireference Perturbation Theory
- Author
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Daisuke Yokogawa, Ryosuke Shimizu, and Takeshi Yanai
- Subjects
Physics ,Excited state ,Density matrix renormalization group ,Solvation ,Molecule ,State (functional analysis) ,Physical and Theoretical Chemistry ,Perturbation theory ,Molecular physics ,Computer Science Applications - Abstract
Determination of excited states of near-infrared (NIR) bioimaging dyes is a challenging theoretical task because of their energy levels with a small gap and the presence of solvation. In the previous study, we showed that the development of the reference interaction site model coupled with the complete active space second-order perturbation theory, the RISM-CASPT2 method, and its extension with the density matrix renormalization group enabled high accuracy prediction of the photochemical properties of bioimaging-related fluorescent molecules in solution (Shimizu et al.
- Published
- 2020
5. Quantum optical synthesis in 2D time-frequency space
- Author
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Fumihiro China, Ryosuke Shimizu, Kurumi Tazawa, Naoto Asamura, Masahiro Yabuno, Rui-Bo Jin, Kaoru Minoshima, Shigehito Miki, and Hirotaka Terai
- Subjects
Quantum optics ,Physics ,Quantum Physics ,Photon ,Computer Networks and Communications ,business.industry ,Wave packet ,Quantum correlation ,Fourier optics ,Optical physics ,Physics::Optics ,FOS: Physical sciences ,Atomic and Molecular Physics, and Optics ,TA1501-1820 ,symbols.namesake ,Optics ,Fourier transform ,symbols ,Applied optics. Photonics ,business ,Quantum Physics (quant-ph) ,Ultrashort pulse - Abstract
Conventional optical synthesis, the manipulation of the phase and amplitude of spectral components to produce an optical pulse in different temporal modes, is revolutionizing ultrafast optical science and metrology. These technologies rely on the Fourier transform of light fields between time and frequency domains in one-dimensional space. However, within this treatment it is impossible to incorporate the quantum correlation among photons. Here we expand the Fourier synthesis into high dimensional space to deal with the quantum correlation, and carry out an experimental demonstration by manipulating the two-photon probability distribution of a biphoton in two-dimensional time and frequency space. As a potential application, we show manipulation of a heralded single-photon wave packet, which is never explained by the conventional one-dimensional Fourier optics. Our approach opens up a new pathway to tailor the temporal characteristics of a biphoton wave packet with high dimensional quantum-mechanical treatment. We anticipate such high dimensional treatment of light in time and frequency domains could bridge the research fields between quantum optics and ultrafast optical measurements., Comment: 12 pages, 7 figures
- Published
- 2020
- Full Text
- View/download PDF
6. Broadband-laser-diode pumped periodically poled potassium titanyl phosphate-Sagnac polarization-entangled photon source
- Author
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Wu-Hao Cai, Fang Li, Ryosuke Shimizu, Neng Cai, Shun Wang, and Rui-Bo Jin
- Subjects
Physics ,Bell state ,business.industry ,Bandwidth (signal processing) ,Statistical and Nonlinear Physics ,Laser pumping ,Polarization (waves) ,Signal ,Atomic and Molecular Physics, and Optics ,Wavelength ,Optics ,Bell's theorem ,business ,Diode - Abstract
We experimentally demonstrate a polarization-entangled photon source at 810 nm using a type-II phase-matched periodically poled potassium titanyl phosphate (PPKTP) crystal pumped by a low-cost, broadband laser diode with a central wavelength of 405 nm and a typical bandwidth of 0.53 nm. The PPKTP crystal is placed in a Sagnac loop to realize the compact size and high stability. The downconverted biphotons, the signal and the idler, have typical bandwidths of 5.57 and 7.32 nm. We prepare two Bell states | Ψ + ⟩ and | Ψ − ⟩ with the fidelities of 0.948 ± 0.004 and 0.963 ± 0.002 . In the polarization correlation measurement, the visibilities are all higher than 96.2%, and in the Bell inequality test, the S value can achieve 2.78 ± 0.01 . This high-quality and low-cost entangled photon source may have many practical applications in quantum information processing.
- Published
- 2021
7. Spectrally uncorrelated biphotons generated from 'the family of BBO crystal'
- Author
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Guang-Wei Deng, Feng Mei, Ryosuke Shimizu, Rui-Bo Jin, Chunling Ding, Wu-Hao Cai, and Qiang Zhou
- Subjects
Physics ,Quantum Physics ,Photon ,business.industry ,Physics::Optics ,FOS: Physical sciences ,Interference (wave propagation) ,Nonlinear system ,Wavelength ,Optics ,Quantum information ,Photonics ,BIBO stability ,business ,Quantum Physics (quant-ph) ,Quantum - Abstract
Spectrally intrinsically uncorrelated biphoton states generated from nonlinear crystals are very important but rare resources for quantum photonics and quantum information applications. Previously, such biphoton states were generated from several kinds of crystals, however, their wavelength ranges and nonlinear efficiencies were still limited for various applications. In order to explore new crystal for wider wavelength range and higher nonlinear efficiency, here we theoretically study the generation of spectrally uncorrelated biphoton states from 14 crystals in the `BBO family', including BBO, CLBO, KABO, KBBF, RBBF, CBBF, BABF, BiBO, LBO, CBO, LRB4, LCB, YCOB, and GdCOB. They satisfy three kinds of group-velocity matching condition from near-infrared to telecom wavelengths. Furthermore, heralded single photons can be generated with a purity as high as 0.98, which is achieved without any narrow filtering. The indistinguishability of photons from independent sources is examined by the Hong-Ou-Mandel interference, which results in a visibility of 98% also without any further filtering, i.e., photons from different heralded single-photon sources are highly indistinguishable. Our study may provide single-photon sources with good performance for quantum information processing at near-infrared and telecom wavelengths., Comment: 10 pages, 6 figures
- Published
- 2019
- Full Text
- View/download PDF
8. Generation of pseudo-sunlight via quantum entangled photons and the interaction with molecules
- Author
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Akihito Ishizaki, Ryosuke Shimizu, and Yuta Fujihashi
- Subjects
Sunlight ,Physics ,Quantum Physics ,Photon ,Photon entanglement ,Quantum mechanics ,Molecule ,Physics::Optics ,FOS: Physical sciences ,Quantum entanglement ,Quantum Physics (quant-ph) ,Quantum ,Parametric statistics - Abstract
Light incident upon molecules trigger fundamental processes in diverse systems present in nature. However, under natural conditions, such as sunlight illumination, it is impossible to assign known times for photon arrival owing to continuous pumping, and therefore, the photo-induced processes cannot be easily investigated. In this work, we theoretically demonstrate that characteristics of sunlight photons such as photon number statistics and spectral distribution can be emulated through quantum entangled photon pair generated with the parametric down-conversion (PDC). We show that the average photon number of the sunlight in a specific frequency spectrum, e.g., the visible light, can be reconstructed by adjusting the PDC crystal length and pump frequency, and thereby molecular dynamics induced by the pseudo-sunlight can be investigated. The entanglement time, which is the hallmark of quantum entangled photons, can serve as a control knob to resolve the photon arrival times, enabling investigations on real-time dynamics triggered by the pseudo-sunlight photons., Comment: 7 pages
- Published
- 2019
- Full Text
- View/download PDF
9. Direct generation of frequency-bin entangled photons via two-period quasi-phase-matched parametric downconversion
- Author
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Hirofumi Suzuki, Keiichi Edamatsu, Ryosuke Shimizu, and Fumihiro Kaneda
- Subjects
Photon ,FOS: Physical sciences ,02 engineering and technology ,Quantum entanglement ,01 natural sciences ,Bin ,010309 optics ,Photon entanglement ,Optics ,Quantum mechanics ,0103 physical sciences ,Photon polarization ,Quantum ,Parametric statistics ,Physics ,Quantum Physics ,business.industry ,021001 nanoscience & nanotechnology ,Polarization (waves) ,Atomic and Molecular Physics, and Optics ,Quantum Physics (quant-ph) ,0210 nano-technology ,business ,Optics (physics.optics) ,Physics - Optics - Abstract
We report a simple scheme for direct generation of frequency-bin entangled photon pairs via spontaneous parametric downconversion. Our fabricated nonlinear optical crystal with two different poling periods can simultaneously satisfy two different, spectrally symmetric nondegenerate quasi-phase-matching conditions, enabling the direct generation of entanglement in two discrete frequency-bin modes. Our produced photon pairs exhibited Hong-Ou-Mandel interference with high-visibility beating oscillations, a signature of two-mode frequency-bin entanglement. Moreover, we demonstrate deterministic entanglement-mode conversion from frequency-bin to polarization modes, with which our source can be more versatile for various quantum applications. Our scheme can be extended to direct generation of high-dimensional frequency-bin entanglement, and thus will be a key technology for frequency-multiplexed optical quantum information processing.
- Published
- 2018
10. Time-Frequency Duality of Biphotons for Quantum Optical Synthesis
- Author
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Rui-Bo Jin, Ryosuke Shimizu, and Takuma Saito
- Subjects
Physics ,Photon ,Optical physics ,General Physics and Astronomy ,Frequency space ,01 natural sciences ,Duality (electricity and magnetism) ,Time–frequency analysis ,010309 optics ,symbols.namesake ,Fourier transform ,Quantum mechanics ,0103 physical sciences ,symbols ,010306 general physics ,Quantum - Abstract
Time-frequency duality plays a pivotal role in modern optical science and engineering. Conventional duality, which is connected by one-dimensional Fourier transformation, is insufficient for characterizing quantum mechanical correlations in the time-frequency behavior of multiple photons; a higher-dimensional treatment is required. The authors directly measure the two-photon distributions of generated biphotons in both frequency and time domains, and show that they satisfy the Fourier-limited condition in two-dimensional time and frequency space, but not in conventional one-dimensional space. This study helps to pave the way to tomorrow's quantum optical technologies.
- Published
- 2018
11. Quantum interferometric spectroscopy
- Author
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Rui-Bo Jin and Ryosuke Shimizu
- Subjects
Physics ,Photon ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Interference (wave propagation) ,01 natural sciences ,symbols.namesake ,Interferometry ,Fourier transform ,0103 physical sciences ,symbols ,Physics::Chemical Physics ,Atomic physics ,010306 general physics ,0210 nano-technology ,NOON state ,Spectroscopy ,Wave function ,Quantum ,Computer Science::Information Theory - Abstract
The difference and sum-frequency distribution of the biphoton wavefunctions were extracted by applying a Fourier transform on the time-domain Hong-Ou-Mandel interference (HOMI) and the NOON state interference (NOONI) patterns.
- Published
- 2018
12. Quantum manipulation of biphoton spectral distributions in a 2D frequency space toward arbitrary shaping of a biphoton wave packet
- Author
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Ryoji Shiina, Rui-Bo Jin, and Ryosuke Shimizu
- Subjects
Physics ,Quantum Physics ,business.industry ,Electromagnetically induced transparency ,Wave packet ,Phase (waves) ,FOS: Physical sciences ,02 engineering and technology ,Quantum channel ,021001 nanoscience & nanotechnology ,Interference (wave propagation) ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Optics ,0103 physical sciences ,Waveform ,010306 general physics ,0210 nano-technology ,business ,Quantum Physics (quant-ph) ,Quantum ,Photonic-crystal fiber - Abstract
In this work, we experimentally manipulate the spectrum and phase of a biphoton wave packet in a two-dimensional frequency space. The spectrum is shaped by adjusting the temperature of the crystal, and the phase is controlled by tilting the dispersive glass plate. The manipulating effects are confirmed by measuring the two-photon spectral intensity (TSI) and the Hong-Ou-Mandel (HOM) interference patterns. Unlike the previous independent manipulation schemes, here we perform joint manipulation on the biphoton spectrum. The technique in this work paves the way for arbitrary shaping of a multi-photon wave packet in a quantum manner., Comment: 4 pages, 4 figures
- Published
- 2018
- Full Text
- View/download PDF
13. Efficient detection of an ultra-bright single-photon source using superconducting nanowire single-photon detectors
- Author
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Taro Yamashita, Masahide Sasaki, Shigehito Miki, Kentaro Wakui, Zhen Wang, Hirotaka Terai, Mikio Fujiwara, Ryosuke Shimizu, and Rui-Bo Jin
- Subjects
Physics ,Superconductivity ,business.industry ,Detector ,Nanowire ,Physics::Optics ,Superconducting nanowire single-photon detector ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,Wavelength ,Optics ,Single-photon source ,Optoelectronics ,Electrical and Electronic Engineering ,Physical and Theoretical Chemistry ,business ,Quantum information science ,Coherence (physics) - Abstract
We investigate the detection of a single-photon source using highly efficient superconducting nanowire single-photon detectors (SNSPDs) at telecom wavelengths. Both the single-photon source and the detectors are characterized in detail. At a pump power of 100 mW (400 mW), the measured coincidence counts can achieve 400 kcps (1.17 Mcps), which is the highest ever reported at telecom wavelengths to the best of our knowledge. The multi-pair contributions, the experimental and theoretical second order coherence functions, and the saturation property of SNSPD are analyzed in detail. The experimental data and theoretical analysis should be useful for the future experiments to detect ultra-bright down-conversion sources with high-efficiency detectors.
- Published
- 2015
14. Monotonic quantum-to-classical transition enabled by positively correlated biphotons
- Author
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Rui-Bo Jin, Guo-Qun Chen, Changliang Ren, Pei Zhao, Peixiang Lu, Ryosuke Shimizu, and Hui Jing
- Subjects
Physics ,Quantum Physics ,Photon ,FOS: Physical sciences ,Monotonic function ,02 engineering and technology ,Quantum entanglement ,021001 nanoscience & nanotechnology ,Interference (wave propagation) ,01 natural sciences ,Uncorrelated ,Quantum mechanics ,0103 physical sciences ,Quantum Physics (quant-ph) ,010306 general physics ,0210 nano-technology ,Quantum - Abstract
Multiparticle interference is a fundamental phenomenon in the study of quantum mechanics.It was discovered in a recent experiment [Ra, Y.-S. et al, Proc. Natl Acad. Sci. USA \textbf{110}, 1227(2013)] that spectrally uncorrelated biphotons exhibited a nonmonotonic quantum-to-classical transition in a four-photon Hong-Ou-Mandel (HOM) interference. In this work, we consider the same scheme with spectrally correlated photons.By theoretical calculation and numerical simulation, we found the transition not only can be nonmonotonic with negative-correlated or uncorrelated biphotons, but also can be monotonic with positive-correlated biphotons. The fundamental reason for this difference is that the HOM-type multi-photon interference is a differential-frequency interference. Our study may shed new light on understanding the role of frequency entanglement in multi-photon behavior., Comment: 8 pages, 2 figures
- Published
- 2017
15. Detection-dependent six-photon Holland-Burnett state interference
- Author
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Mikio Fujiwara, Taro Yamashita, Ryosuke Shimizu, Hirotaka Terai, Rui-Bo Jin, Gerald S. Buller, Masahiro Takeoka, Masahide Sasaki, Robert J. Collins, and Shigehito Miki
- Subjects
Physics ,Coherence time ,Multidisciplinary ,Photon ,business.industry ,Phase (waves) ,Interference (wave propagation) ,01 natural sciences ,Article ,010309 optics ,Optics ,0103 physical sciences ,Quantum metrology ,010306 general physics ,business ,NOON state ,Optical path length ,Envelope (waves) - Abstract
The NOON state, and its experimental approximation the Holland-Burnett state, have important applications in phase sensing measurement with enhanced sensitivity. However, most of the previous Holland-Burnett state interference (HBSI) experiments only investigated the area of the interference pattern in the region immediately around zero optical path length difference, while the full HBSI pattern over a wide range of optical path length differences has not yet been well explored. In this work, we experimentally and theoretically demonstrate up to six-photon HBSI and study the properties of the interference patterns over a wide range of optical path length differences. It was found that the shape, the coherence time and the visibility of the interference patterns were strongly dependent on the detection schemes. This work paves the way for applications which are based on the envelope of the HBSI pattern, such as quantum spectroscopy and quantum metrology.
- Published
- 2016
16. Spectrally resolved Hong-Ou-Mandel interference between independent photon sources
- Author
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Ryosuke Shimizu, Rui-Bo Jin, Thomas Gerrits, Masahide Sasaki, Masahiro Takeoka, Taro Yamashita, Ryota Wakabayashi, Shigehito Miki, Mikio Fujiwara, and Hirotaka Terai
- Subjects
Physics ,Quantum Physics ,Photon ,Spectral power distribution ,Spectrometer ,business.industry ,FOS: Physical sciences ,Interference (wave propagation) ,Atomic and Molecular Physics, and Optics ,Optics ,Quantum gate ,Sampling (signal processing) ,business ,Quantum Physics (quant-ph) ,Block (data storage) ,Boson - Abstract
Hong-Ou-Mandel (HOM) interference between independent photon sources (HOMI-IPS) is the fundamental block for quantum information processing, such as quantum gate, Shor's algorithm, Boson sampling, etc. All the previous HOMI-IPS experiments were carried out in time-domain, however, the spectral information during the interference was lost, due to technical difficulties. Here, we investigate the HOMI-IPS in spectral domain using the recently developed fast fiber spectrometer, and demonstrate the spectral distribution during the HOM interference between two heralded single-photon sources, and two thermal sources. This experiment can not only deepen our understanding of HOMI-IPS in the spectral domain, but also be utilized to improve the visibility by post-processing spectral filtering., Comment: 8 pages, 7 figures
- Published
- 2015
17. Extended Wiener–Khinchin theorem for quantum spectral analysis
- Author
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Rui-Bo Jin and Ryosuke Shimizu
- Subjects
Quantum optics ,Physics ,Quantum Physics ,Photon ,Fundamental theorem ,FOS: Physical sciences ,Wiener–Khinchin theorem ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,010309 optics ,symbols.namesake ,Fourier transform ,Quantum mechanics ,0103 physical sciences ,symbols ,Quantum Physics (quant-ph) ,010306 general physics ,Wave function ,NOON state ,Quantum - Abstract
The classical Wiener-Khinchin theorem (WKT), which can extract spectral information by classical interferometers through Fourier transform, is a fundamental theorem used in many disciplines. However, there is still need for a quantum version of WKT, which could connect correlated biphoton spectral information by quantum interferometers. Here, we extend the classical WKT to its quantum counterpart, i.e., extended WKT (e-WKT), which is based on two-photon quantum interferometry. According to the e-WKT, the difference-frequency distribution of the biphoton wavefunctions can be extracted by applying a Fourier transform on the time-domain Hong-Ou-Mandel interference (HOMI) patterns, while the sum-frequency distribution can be extracted by applying a Fourier transform on the time-domain NOON state interference (NOONI) patterns. We also experimentally verified the WKT and e-WKT in a Mach-Zehnder interference (MZI), a HOMI and a NOONI. This theorem can be directly applied to quantum spectroscopy, where the spectral correlation information of biphotons can be obtained from time-domain quantum interferences by Fourier transform. This may open a new pathway for the study of light-matter interaction at the single photon level., 13 pages, 5 figures
- Published
- 2018
18. Observation of optical-fibre Kerr nonlinearity at the single-photon level
- Author
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Hideo Kosaka, Yasuyoshi Mitsumori, Nobuyuki Matsuda, Keiichi Edamatsu, and Ryosuke Shimizu
- Subjects
Physics ,Quantum optics ,Quantum Physics ,Atomic Physics (physics.atom-ph) ,business.industry ,FOS: Physical sciences ,Physics::Optics ,Soliton (optics) ,Atomic and Molecular Physics, and Optics ,Physics - Atomic Physics ,Electronic, Optical and Magnetic Materials ,Supercontinuum ,Optics ,Dispersion (optics) ,Optoelectronics ,Quantum information ,Photonics ,Quantum Physics (quant-ph) ,business ,Ultrashort pulse ,Optics (physics.optics) ,Physics - Optics ,Photonic crystal - Abstract
Optical fibres have proved to be an important medium for manipulating and generating light in applications including soliton transmission1, light amplification2, all-optical switching3 and supercontinuum generation4. In the quantum regime, fibres may prove useful for ultralow-power all-optical signal processing5 and quantum information processing6. Here, we demonstrate the first experimental observation of optical nonlinearity at the single-photon level in an optical fibre. Taking advantage of the large nonlinearity and managed dispersion of photonic crystal fibres7,8, we report very small (1 × 10−7 to ∼1 × 10−8 rad) conditional phase shifts induced by weak coherent pulses that contain one or less than one photon per pulse on average. We discuss the feasibility of quantum information processing using optical fibres, taking into account the observed Kerr nonlinearity, accompanied by ultrafast response time and low induced loss. The tiny phase changes introduced by nonlinear optics performed at the single-photon level is reported in a photonic crystal fibre with carefully designed nonlinear and dispersion properties. The approach may prove useful in future quantum information processing schemes.
- Published
- 2009
19. Highly efficient entanglement swapping and teleportation at telecom wavelength
- Author
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Rui-Bo Jin, Ryosuke Shimizu, Masahiro Takeoka, Masahide Sasaki, and Utako Takagi
- Subjects
Physics ,Quantum Physics ,Quantum network ,Multidisciplinary ,Optical fiber ,Photon ,business.industry ,FOS: Physical sciences ,Physics::Optics ,Quantum entanglement ,Quantum key distribution ,Interference (wave propagation) ,Teleportation ,Article ,law.invention ,Wavelength ,law ,Quantum Physics (quant-ph) ,Telecommunications ,business - Abstract
Entanglement swapping at telecom wavelengths is at the heart of quantum networking in optical fiber infrastructures. Although entanglement swapping has been demonstrated experimentally so far using various types of entangled photon sources both in near-infrared and telecom wavelength regions, the rate of swapping operation has been too low to be applied to practical quantum protocols, due to limited efficiency of entangled photon sources and photon detectors. Here we demonstrate drastic improvement of the efficiency at telecom wavelength by using two ultra-bright entangled photon sources and four highly efficient superconducting nanowire single photon detectors.We have attained a four-fold coincidence count rate of 108 counts per second, which is three orders higher than the previous experiments at telecom wavelengths. A raw (net) visibility in a Hong-Ou-Mandel interference between the two independent entangled sources was 73.3 $\pm$ 1.0% (85.1 $\pm$ 0.8%). We performed the teleportation and entanglement swapping, and obtained a fidelity of 76.3% in the swapping test.Our results on the coincidence count rates are comparable with the ones ever recorded in teleportation/swaping and multi-photon entanglement generation experiments at around 800\,nm wavelengths. Our setup opens the way to practical implementation of device-independent quantum key distribution and its distance extension by the entanglement swapping as well as multi-photon entangled state generation in telecom band infrastructures with both space and fiber links., Comment: 9 pages, 5 figures
- Published
- 2015
20. Efficient Generation of Twin Photons at Telecom Wavelengths with 10 GHz Repetition-Rate-Tunable Comb Laser
- Author
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Shuro Izumi, Isao Morohashi, Mikio Fujiwara, Shigehito Miki, Takahide Sakamoto, Ryosuke Shimizu, Rui-Bo Jin, Taro Yamashita, Hirotaka Terai, Masahide Sasaki, Zhen Wang, Masahiro Takeoka, and Kentaro Wakui
- Subjects
Quantum optics ,Physics ,Photon ,business.industry ,Detector ,Nonlinear optics ,Laser ,law.invention ,Wavelength ,Optics ,Interference (communication) ,law ,Optoelectronics ,Photonics ,business - Abstract
We demonstrate a down-conversion-based twin photon source pumped by a 10 GHz repetition-rate-tunable comb laser at 1553 nm wavelength. We show high Hong-Ou-Mandel interference visibilities, which are free from the pump-power induced degradation.
- Published
- 2015
21. Quantum interference and diffraction of parametric down-converted biphotons
- Author
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Keiichi Edamatsu, Tadashi Itoh, and Ryosuke Shimizu
- Subjects
Diffraction ,Physics ,Photon ,business.industry ,Physics::Optics ,General Physics and Astronomy ,Quantum lithography ,Interference (wave propagation) ,Wavelength ,Optics ,Spontaneous parametric down-conversion ,Physics::Chemical Physics ,business ,Diffraction grating ,Parametric statistics - Abstract
We present two-photon diffraction and interference experiments utilizing parametric down-converted photon pairs (biphotons) and a transmission grating. The biphoton exhibits a diffraction-interference pattern equivalent to an effective single particle with half wavelength of the constituent photons.
- Published
- 2002
22. Efficient generation of twin photons at telecom wavelengths with 2.5 GHz repetition-rate-tunable comb laser
- Author
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Rui-Bo Jin, Ryosuke Shimizu, Masahiro Takeoka, Hirotaka Terai, Isao Morohashi, Taro Yamashita, Shigehito Miki, Kentaro Wakui, Zhen Wang, Mikio Fujiwara, Shuro Izumi, Takahide Sakamoto, and Masahide Sasaki
- Subjects
Physics ,Multidisciplinary ,Photon ,business.industry ,Nanowire ,Ti:sapphire laser ,Physics::Optics ,Laser ,Article ,law.invention ,Interference (communication) ,Spontaneous parametric down-conversion ,law ,Photonics ,Quantum information ,business ,Telecommunications - Abstract
Efficient generation and detection of indistinguishable twin photons are at the core of quantum information and communications technology (Q-ICT). These photons are conventionally generated by spontaneous parametric down conversion (SPDC), which is a probabilistic process and hence occurs at a limited rate, which restricts wider applications of Q-ICT. To increase the rate, one had to excite SPDC by higher pump power, while it inevitably produced more unwanted multi-photon components, harmfully degrading quantum interference visibility. Here we solve this problem by using recently developed 10 GHz repetition-rate-tunable comb laser, combined with a group-velocity-matched nonlinear crystal and superconducting nanowire single photon detectors. They operate at telecom wavelengths more efficiently with less noises than conventional schemes, those typically operate at visible and near infrared wavelengths generated by a 76 MHz Ti Sapphire laser and detected by Si detectors. We could show high interference visibilities, which are free from the pump-power induced degradation. Our laser, nonlinear crystal and detectors constitute a powerful tool box, which will pave a way to implementing quantum photonics circuits with variety of good and low-cost telecom components and will eventually realize scalable Q-ICT in optical infra-structures.
- Published
- 2014
23. Pulsed Sagnac polarization-entangled photon source with a PPKTP crystal at telecom wavelength
- Author
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Masahide Sasaki, Shigehito Miki, Rui-Bo Jin, Ryosuke Shimizu, Taro Yamashita, Hirotaka Terai, Zhen Wang, Mikio Fujiwara, and Kentaro Wakui
- Subjects
Quantum optics ,Superconductivity ,Physics ,Quantum Physics ,Photon ,business.industry ,Photon source ,Nanowire ,FOS: Physical sciences ,Physics::Optics ,Quantum key distribution ,Quantum information processing ,Polarization (waves) ,Atomic and Molecular Physics, and Optics ,Wavelength ,Interferometry ,Optics ,Optoelectronics ,Quantum information science ,Telecommunications ,business ,Quantum Physics (quant-ph) ,Spectral purity - Abstract
We demonstrate pulsed polarization-entangled photons generated from a periodically poled $\mathrm{KTiOPO_4}$ (PPKTP) crystal in a Sagnac interferometer configuration at telecom wavelength. Since the group-velocity-matching (GVM) condition is satisfied, the intrinsic spectral purity of the photons is much higher than in the previous scheme at around 800 nm wavelength. The combination of a Sagnac interferometer and the GVM-PPKTP crystal makes our entangled source compact, stable, highly entangled, spectrally pure and ultra-bright. The photons were detected by two superconducting nanowire single photon detectors (SNSPDs) with detection efficiencies of 70% and 68% at dark counts of less than 1 kcps. We achieved fidelities of 0.981 $\pm$ 0.0002 for $\left| {\psi ^ -} \right\rangle$ and 0.980 $\pm$ 0.001 for $\left| {\psi ^ +} \right\rangle$ respectively. This GVM-PPKTP-Sagnac scheme is directly applicable to quantum communication experiments at telecom wavelength, especially in free space., Comment: 5 pages, 5 figures http://dx.doi.org/10.1364/OE.22.011498
- Published
- 2014
24. Erratum: Nonclassical interference between independent intrinsically pure single photons at telecommunication wavelength [Phys. Rev. A87, 063801 (2013)]
- Author
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Kentaro Wakui, Rui-Bo Jin, Masahide Sasaki, Shigehito Miki, Mikio Fujiwara, Zhen Wang, Hirotaka Terai, Hugo Benichi, Ryosuke Shimizu, and Taro Yamashita
- Subjects
Physics ,Wavelength ,Photon ,Quantum mechanics ,Quantum information science ,Interference (wave propagation) ,Atomic and Molecular Physics, and Optics - Published
- 2014
25. Entangled-state generation with an intrinsically pure single-photon source and a weak coherent source
- Author
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Rui-Bo Jin, Ryosuke Shimizu, Yasuyoshi Mitsumori, Fumihiro Kaneda, Hideo Kosaka, and Keiichi Edamatsu
- Subjects
Physics ,Quantum Physics ,Measurement theory ,Photon ,Quantum mechanics ,Single-photon source ,FOS: Physical sciences ,Coherent states ,State (functional analysis) ,Quantum entanglement ,Quantum information ,Quantum Physics (quant-ph) ,Atomic and Molecular Physics, and Optics - Abstract
We report on the experimental generation of an entangled state with a spectrally pure heralded single-photon state and a weak coherent state. By choosing group-velocity matching in the nonlinear crystal, our system for producing entangled photons was 60 times brighter than that in the earlier experiment [Phys. Rev. Lett. 90, 240401 (2003)], with no need of bandpass filters. This entanglement system is useful for quantum information protocols that require indistinguishable photons from independent sources., Comment: 7 pages, 5 figures
- Published
- 2013
26. Nonclassical interference between independent intrinsically pure single photons at telecommunication wavelength
- Author
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Shigehito Miki, Mikio Fujiwara, Rui-Bo Jin, Taro Yamashita, Hugo Benichi, Kentaro Wakui, Zhen Wang, Masahide Sasaki, Ryosuke Shimizu, and Hirotaka Terai
- Subjects
Physics ,Photon ,business.industry ,Detector ,Nanowire ,Atomic and Molecular Physics, and Optics ,Wavelength ,Optics ,Interference (communication) ,Band-pass filter ,Optoelectronics ,business ,Telecommunications ,Quantum information science ,Quantum - Abstract
We demonstrate a Hong-Ou-Mandel interference between two independent, intrinsically pure, heralded single photons from spontaneous parametric down-conversion (SPDC) at telecommunication wavelength. A visibility of $85.5\ifmmode\pm\else\textpm\fi{}8.3%$ was achieved without using any bandpass filter. Thanks to the group-velocity-matched SPDC and superconducting nanowire single-photon detectors (SNSPDs), the fourfold coincidence counts are one order higher than that in the previous experiments. The combination of bright single-photon sources and SNSPDs is a crucial step for future practical quantum infocommunication systems at telecommunication wavelength.
- Published
- 2013
27. Widely-tunable, spectrally pure, high efficient photon pairs generation at telecom wavelength
- Author
-
Rui-Bo Jin, Hugo Benichi, Ryosuke Shimizu, Kentaro Wakui, and Masahide Sasaki
- Subjects
Physics ,Photon ,business.industry ,Computation ,Photon source ,Physics::Optics ,Second-harmonic generation ,Crystal ,Wavelength ,Optics ,Spontaneous parametric down-conversion ,Optoelectronics ,Quantum information ,business - Abstract
Photon source is one of the fundamental bricks for quantum information and computation systems. A widely-tunable, highly efficient and spectrally pure photon source would be very useful for such applications. In this paper, we present such a source based on spontaneous parametric down conversion (SPDC) in a periodically poled KTiOPO4 (PPKTP) crystal.
- Published
- 2013
28. Entangled photon generation in two-period quasi-phase-matched parametric down-conversion
- Author
-
Hirofumi Suzuki, Atsushi Syouji, Koji Suizu, Ryosuke Shimizu, Wakana Ueno, Keiichi Edamatsu, Shigehiro Nagano, and Fumihiro Kaneda
- Subjects
Quantum optics ,Physics ,Photons ,Photon ,business.industry ,Poling ,Physics::Optics ,Equipment Design ,Polarization (waves) ,Atomic and Molecular Physics, and Optics ,Equipment Failure Analysis ,Photon entanglement ,Optics ,Interferometry ,Spontaneous parametric down-conversion ,Photon polarization ,Telecommunications ,business ,Circular polarization - Abstract
We proposed and demonstrated a simple but deterministic scheme for generating polarization-entangled photon pairs at telecommunication wavelengths with type-II quasi-phase-matched spontaneous parametric down-conversion (QPM-SPDC) having two poling periods. We fabricated a LiNbO3 crystal having two poling periods so as to generate entangled photons at two wavelengths, i.e., 1506 nm and 1594 nm. We characterized the two-photon polarization state with state tomography and confirmed that the state was highly entangled.
- Published
- 2012
29. Efficient generation and activation of bound entanglement in optical qubits
- Author
-
Satoshi Ishizaka, Hideo Kosaka, Keiichi Edamatsu, Ryosuke Shimizu, Fumihiro Kaneda, and Yasuyoshi Mitsumori
- Subjects
Physics ,Bell state ,TheoryofComputation_COMPUTATIONBYABSTRACTDEVICES ,TheoryofComputation_GENERAL ,Data_CODINGANDINFORMATIONTHEORY ,Quantum Physics ,Quantum entanglement ,Squashed entanglement ,Multipartite entanglement ,General Relativity and Quantum Cosmology ,Physics::Popular Physics ,Superdense coding ,Quantum mechanics ,W state ,Quantum teleportation ,Entanglement witness - Abstract
We report the efficient generation of a four-qubit bound entangled Smolin state. We also demonstrate the activation of the bound entanglement; we make the bound entanglement in the Smolin state distillable with the help of an additional Bell pair.
- Published
- 2011
30. Generation and superactivation of bound entanglement
- Author
-
Ryosuke Shimizu, Yasuyoshi Mitsumori, Fumihiro Kaneda, Satoshi Ishizaka, Hideo Kosaka, and Keiichi Edamatsu
- Subjects
Physics ,LOCC ,Spontaneous parametric down-conversion ,Quantum mechanics ,Quantum Physics ,Quantum entanglement ,W state ,Squashed entanglement ,Realization (systems) ,Multipartite entanglement ,Entanglement witness - Abstract
We report the experimental realization of the four-partite bound-entangled state, i.e., Smolin state [1] and demonstrate the ‘superactivation’ of the bound entanglement. Bound entanglement is a class of multipartite entanglement that cannot be distilled into pure entanglement under local operations and classical communication (LOCC). Despite its undistillable property, this class of entanglement has interesting properties that are expected to be useful in quantum information processing (QIP). For instance, in the Smolin state, the bound entanglement can be activated into distillable entanglement when two of the parties get together. The process is called “unlocking” [1], and has been demonstrated experimentally [2]. More importantly, the bound entanglement can be activated with the help of entanglement in other systems [3]. The activation of bound entanglement, i.e., superactivation, plays an essential role in the QIP protocols using bound entangled states (e.g., remote information concentration [4]).
- Published
- 2011
31. Measurement of reduced four-photon de Broglie wavelength at telecom wavelength
- Author
-
Masahiro Yabuno, Hideo Kosaka, Yasuyoshi Mitsumori, Ryosuke Shimizu, and Keiichi Edamatsu
- Subjects
Diffraction ,Quantum optics ,Physics ,Photon ,business.industry ,Quantum limit ,Physics::Optics ,Quantum entanglement ,Wavelength ,Optics ,Matter wave ,Quantum information ,Telecommunications ,business - Abstract
The reduction of de Broglie wavelength is one of the fascinating characteristics of multiphoton quantum interference. It will be applicable to, for instance, super-resolution imaging beyond the classical diffraction limit and ultrasensitive phase measurement beyond the standard quantum limit. Thus far, the reduced de Broglie wavelength has been experimentally demonstrated using visible or near infrared photons [1–3]. However, it is still a challenging task to demonstrate multiphoton quantum interference in a telecom-wavelength region, because of insufficient quantum efficiencies of single-photon detectors working at telecom wavelength. Also, efficient photon sources of multiple photons that are mutually indistinguishable are essential to carry out various experiments including multiphoton quantum interference and quantum information protocols. In this context, we have developed an efficient photon-pair source designed for such multiphoton experiments at telecom wavelength. Making use of this source, we demonstrate the first measurement of reduced de Broglie wavelength of the four-photon state at the telecom wavelength.
- Published
- 2011
32. High-visibility nonclassical interference between intrinsically pure heralded single photons and photons from a weak coherent field
- Author
-
Ryosuke Shimizu, Nobuyuki Matsuda, Hideo Kosaka, Keiichi Edamatsu, Yasuyoshi Mitsumori, Rui-Bo Jin, and Jun Zhang
- Subjects
Physics ,Photon ,Dark state ,Quantum mechanics ,Quantum electrodynamics ,Coherent states ,Nonclassical light ,Coherent backscattering ,Interference (wave propagation) ,Electromagnetic radiation ,Atomic and Molecular Physics, and Optics ,Boson - Abstract
We present an experiment of nonclassical interference between an intrinsically pure heralded single-photon state and a weak coherent state. Our experiment demonstrates that, without the use of bandpass filters, spectrally pure single photons can have high-visibility ($89.4\ifmmode\pm\else\textpm\fi{}0.5%$) interference with photons from a weak coherent field. Our scheme lays the groundwork for future experiments requiring quantum interference between photons in nonclassical states and those in coherent states.
- Published
- 2011
33. Four-Photon Quantum Interferometry at a Telecom Wavelength
- Author
-
Masahiro Yabuno, Hideo Kosaka, Yasuyoshi Mitsumori, Ryosuke Shimizu, and Keiichi Edamatsu
- Subjects
Physics ,Quantum Physics ,Photon ,business.industry ,Quantum sensor ,Physics::Optics ,FOS: Physical sciences ,Atomic and Molecular Physics, and Optics ,Interferometry ,Wavelength ,Optics ,Matter wave ,Telecommunications ,business ,Quantum Physics (quant-ph) ,Quantum ,Realization (systems) ,Quantum computer - Abstract
We report the experimental demonstration of four-photon quantum interference using telecom-wavelength photons. Realization of multi-photon quantum interference is essential to linear optics quantum information processing and measurement-based quantum computing. We have developed a source that efficiently emits photon pairs in a pure spectrotemporal mode at a telecom wavelength region, and have demonstrated the quantum interference exhibiting the reduced fringe intervals that correspond to the reduced de Broglie wavelength of up to the four photon `NOON' state. Our result should open a path to practical quantum information processing using telecom-wavelength photons., Comment: 4 pages, 4 figures
- Published
- 2011
- Full Text
- View/download PDF
34. Intrinsic pure single-photon source and its nonclassical interference with weak coherent photons
- Author
-
Rui-Bo Jin, Jun Zhang, Ryosuke Shimizu, Nobuyuki Matsuda, Yasuyoshi Mitsumori, Hideo Kosaka, Keiichi Edamatsu, Timothy Ralph, and Ping Koy Lam
- Subjects
Physics ,Photon ,Spectral power distribution ,Homodyne detection ,Single-photon source ,Quantum mechanics ,Spectral filtering ,Atomic physics ,Coherence (physics) ,Parametric statistics - Abstract
We report the generation of pure single‐photon state in the process of spontaneous parametric down‐conversion with extended phase‐matching condition. The measured joint spectral distribution of the photon pairs shows a high purity of the state we prepared. A visibility of 89.4± 0.5% was achieved without any spectral filtering in a nonclassical Hong‐Ou‐Mandel interference between pure heralded single photons and weak coherent photons.
- Published
- 2011
35. Controlled Frequency Entanglement of Photons in Type-II Spontaneous Parametric Down-Conversion
- Author
-
Keiichi Edamatsu and Ryosuke Shimizu
- Subjects
Physics ,Quantum optics ,Photon ,Spontaneous parametric down-conversion ,Quantum mechanics ,Photon polarization ,Broadband ,Physics::Optics ,Nonlinear optics ,Quantum Physics ,Quantum entanglement ,Physical optics - Abstract
We report broadband entangled photon sources that have control capability of the frequency entanglement. Directly observing the frequency correlation between the constituent photons, we demonstrate the biphoton sources consisting of frequency-correlated or frequency-anticorrelated photons.
- Published
- 2009
36. Generation of polarization entanglement from spatially-correlated photons in spontaneous parametric down-conversion
- Author
-
Ryosuke Shimizu, Takashi Yamaguchi, Yasuyoshi Mitsumori, Keiichi Edamatsu, and Hideo Kosaka
- Subjects
Physics ,Spatial correlation ,Quantum Physics ,Photon ,Michelson interferometer ,FOS: Physical sciences ,Quantum entanglement ,Polarization (waves) ,Atomic and Molecular Physics, and Optics ,law.invention ,Spontaneous parametric down-conversion ,Parametric process ,law ,Quantum electrodynamics ,Quantum mechanics ,Quantum Physics (quant-ph) ,Parametric statistics - Abstract
We propose a novel scheme to generate polarization entanglement from spatially-correlated photon pairs. We experimentally realized a scheme by means of a spatial correlation effect in a spontaneous parametric down-conversion and a modified Michelson interferometer. The scheme we propose in this paper can be interpreted as a conversion process from spatial correlation to polarization entanglement., 4 pages, 4 figures
- Published
- 2007
37. Cross-Polarized Photon Pair Source using Type-II Quasi-Phase Matched Parametric Down-Conversion
- Author
-
Hiromasa Ito, Koji Suizu, Shigehiro Nagano, Y. Sugiura, Keiichi Edamatsu, and Ryosuke Shimizu
- Subjects
Physics ,Optical fiber ,Photon ,business.industry ,Lithium niobate ,Phase (waves) ,Coincidence ,law.invention ,chemistry.chemical_compound ,Optics ,chemistry ,Spontaneous parametric down-conversion ,law ,Electric field ,business ,Parametric statistics - Abstract
We have developed a high-efficiency source of cross-polarized photon pairs in a 800-nm band via type-II quasi-phase matched spontaneous parametric down-conversion using periodically poled lithium niobate. We obtained 25,000 coincidence counts sec-1 mW-1 of the photon pairs.
- Published
- 2007
38. Measurement of optical cross-Kerr nonlinearity induced by a few photons in a photonic crystal fiber
- Author
-
Hideo Kosaka, Ryosuke Shimizu, Yasuyoshi Mitsumori, Nobuyuki Matsuda, and Keiichi Edamatsu
- Subjects
Physics ,Kerr effect ,business.industry ,Cross-phase modulation ,Physics::Optics ,Polarization-maintaining optical fiber ,Microstructured optical fiber ,Optics ,Fiber optic sensor ,Optoelectronics ,Plastic optical fiber ,business ,Photonic-crystal fiber ,Photonic crystal - Abstract
The purpose of our study is to establish the technique to measure such weak cross-Kerr nonlinearity induced by a single photon in solid states. The experimental set-up is based on a pump-probe measurement.
- Published
- 2007
39. Generation of polarization entanglement converted from a spatial correlation in spontaneous parametric down-conversion
- Author
-
Ryosuke Shimizu, Keiichi Edamatsu, Hideo Kosaka, Yasuyoshi Mitsumori, and Takashi Yamaguchi
- Subjects
Physics ,Spatial correlation ,business.industry ,Quantum Physics ,Quantum entanglement ,Polarization (waves) ,Teleportation ,Spontaneous parametric down-conversion ,Quantum mechanics ,High Energy Physics::Experiment ,Photonics ,business ,Photonic crystal ,Parametric statistics - Abstract
We propose and demonstrate a novel scheme to generate a polarization entangled state utilizing a spatial correlation effect in parametric down-conversion. We also demonstrate the violation of Bell's inequality.
- Published
- 2006
40. Measurement of nonlinear phase shifts of a photonic crystal fiber using a polarization-division Sagnac interferometer
- Author
-
Nobuyuki Matsuda, Ryosuke Shimizu, Yasuyoshi Mitsumori, Hideo Kosaka, and Keiichi Edamatsu
- Subjects
Physics ,Optical fiber ,business.industry ,Physics::Optics ,Nonlinear optics ,Optical polarization ,Polarization (waves) ,law.invention ,Optical pumping ,Nonlinear system ,Interferometry ,Optics ,law ,Optoelectronics ,business ,Nonlinear Sciences::Pattern Formation and Solitons ,Photonic-crystal fiber - Abstract
Characterization of small nonlinear phase shifts will be a key to the optical quantum information processing. We propose and demonstrate a novel technique to measure the nonlinear phase shifts in a waveguide-type Kerr medium.
- Published
- 2006
41. Photon polarization entanglement induced by Biexciton: experimental evidence for violation of Bell's inequality
- Author
-
Goro Oohata, Ryosuke Shimizu, and Keiichi Edamatsu
- Subjects
Physics ,Bell state ,Quantum discord ,Quantum Physics ,FOS: Physical sciences ,General Physics and Astronomy ,Physics::Optics ,Quantum entanglement ,Photon entanglement ,Spontaneous parametric down-conversion ,Qubit ,Quantum mechanics ,Quantum electrodynamics ,Photon polarization ,Quantum Physics (quant-ph) ,Quantum teleportation - Abstract
We have investigated the polarization entanglement between photon pairs generated from a biexciton in a CuCl single crystal via resonant hyper parametric scattering. The pulses of a high repetition pump are seen to provide improved statistical accuracy and the ability to test Bell's inequality. Our results clearly violate the inequality and thus manifest the quantum entanglement and nonlocality of the photon pairs. We also analyzed the quantum state of our photon pairs using quantum state tomography., 4 pages, 5 figures
- Published
- 2006
42. GENERATION OF ENTANGLED PHOTONS IN A SEMICONDUCTOR AND VIOLATION OF BELL'S INEQUALITY
- Author
-
Ryosuke Shimizu, Keiichi Edamatsu, and Goro Oohata
- Subjects
Physics ,Bell state ,Photon entanglement ,Photon ,Exciton ,Quantum mechanics ,CHSH inequality ,Bell test experiments ,Quantum entanglement ,Quantum information - Published
- 2006
43. Quantum diffraction and interference of spatially correlated photon pairs and its Fourier-optical analysis
- Author
-
Ryosuke Shimizu, Keiichi Edamatsu, and Tadashi Itoh
- Subjects
Diffraction ,Physics ,Spatial correlation ,Quantum Physics ,Photon ,FOS: Physical sciences ,Physics::Optics ,Interference (wave propagation) ,Atomic and Molecular Physics, and Optics ,Computational physics ,symbols.namesake ,Fourier transform ,Quantum mechanics ,symbols ,Quantum Physics (quant-ph) ,Divergence (statistics) ,Quantum ,Parametric statistics - Abstract
We present one- and two-photon diffraction and interference experiments involving parametric down-converted photon pairs. By controlling the divergence of the pump beam in parametric down-conversion, the diffraction-interference pattern produced by an object changes from a quantum (perfectly correlated) case to a classical (uncorrelated) one. The observed diffraction and interference patterns are accurately reproduced by Fourier-optical analysis taking into account the quantum spatial correlation. We show that the relation between the spatial correlation and the object size plays a crucial role in the formation of both one- and two-photon diffraction-interference patterns., 10 pages, 13 figures, rev.2
- Published
- 2006
44. Entangled-photon generation from biexcitons in a semiconductor
- Author
-
Ryosuke Shimizu, G. Oohata, and K. Edamatsu
- Subjects
Physics ,Quantum optics ,Photon ,Semiconductor ,Band gap ,business.industry ,Wide-bandgap semiconductor ,Nonlinear optics ,Optoelectronics ,business ,Molecular physics ,Biexciton ,Photonic crystal - Abstract
The paper reports the most recent experimental result that exhibits a higher degree of entanglement. They used vapor-phase-grown thin single crystal of CuCl. Since CuCl has a large bandgap (/spl sim/3.4 eV), it is suitable to generate photon pairs in the short wavelength region near ultraviolet.
- Published
- 2006
45. Generation of entangled photons via biexciton-resonant hyper-parametric scattering
- Author
-
Ryosuke Shimizu, G. Oohata, and Keiichi Edamatsu
- Subjects
Physics ,Photon entanglement ,Photon ,Spontaneous parametric down-conversion ,Parametric process ,Scattering ,Quantum mechanics ,Optical polarization ,Quantum entanglement ,Atomic physics ,Biexciton - Abstract
We demonstrate the entangled photon pair generation via biexciton-resonant hyper parametric scattering in CuCl crystal. Quantum tomographic analysis of the polarization correlation measurements showed that the generated photon pairs had a high degree of polarization entanglement, in consequence of J=0 angular momentum of the biexciton state.
- Published
- 2005
46. Entangled photon generation via biexciton-resonant hyper parametric scattering in a semiconductor
- Author
-
Ryosuke Shimizu, K. Edamatsu, and G. Oohata
- Subjects
Physics ,Photon ,Scattering ,business.industry ,Exciton ,Optical polarization ,Mott scattering ,Light scattering ,symbols.namesake ,symbols ,Optoelectronics ,Rayleigh scattering ,Atomic physics ,business ,Biexciton - Published
- 2005
47. Generation of ultraviolet entangled photons in a semiconductor
- Author
-
Keiichi Edamatsu, Goro Oohata, Tadashi Itoh, and Ryosuke Shimizu
- Subjects
Physics ,Multidisciplinary ,Photon ,business.industry ,Physics::Optics ,Quantum Physics ,Quantum entanglement ,Quantum technology ,Semiconductor ,Photon entanglement ,Spontaneous parametric down-conversion ,Quantum mechanics ,Quantum information ,business ,Biexciton - Abstract
Entanglement is one of the key features of quantum information and communications technology. The method that has been used most frequently to generate highly entangled pairs of photons1,2 is parametric down-conversion. Short-wavelength entangled photons are desirable for generating further entanglement between three or four photons, but it is difficult to use parametric down-conversion to generate suitably energetic entangled photon pairs. One method that is expected to be applicable for the generation of such photons3 is resonant hyper-parametric scattering (RHPS): a pair of entangled photons is generated in a semiconductor via an electronically resonant third-order nonlinear optical process. Semiconductor-based sources of entangled photons would also be advantageous for practical quantum technologies, but attempts to generate entangled photons in semiconductors have not yet been successful4,5. Here we report experimental evidence for the generation of ultraviolet entangled photon pairs by means of biexciton resonant RHPS in a single crystal of the semiconductor CuCl. We anticipate that our results will open the way to the generation of entangled photons by current injection, analogous to current-driven single photon sources6,7.
- Published
- 2004
48. Diffraction and interference of entangled photon pairs generated by parametric down-conversion: a spatial correlation effect
- Author
-
Keiichi Edamatsu, Tadashi Itoh, and Ryosuke Shimizu
- Subjects
Physics ,Diffraction ,Quantum optics ,Spatial correlation ,Photon ,Physics::Instrumentation and Detectors ,business.industry ,Wave packet ,Ti:sapphire laser ,Physics::Optics ,Interference (wave propagation) ,Optics ,Spontaneous parametric down-conversion ,business - Abstract
Diffraction-interference patterns of parametric down-converted photons through a transmission grating by both one- and two-photon detection schemes are presented. The measured patterns are explained by the Fourier analysis of the two-photon wave packet, considering the quantum spatial correlation between the constituent photons. Spatial diffraction-interference patterns were recorded by a two-photon detector consisting of two avalanche photodiodes. For comparison, diffraction-interference patterns of Ti:sapphire laser are also observed using the same apparatus (a uncorrelated case).
- Published
- 2003
49. 709 Vibration Control using Hula-Hoop with Torque Assistance
- Author
-
Shuhei Kajihara, Ryosuke Shimizu, Humiya Miyagawa, Akira Harada, and Yutaka Yoshitake
- Subjects
Physics ,Hula ,Torque motor ,Control theory ,Vibration control ,Torque ,Damping torque - Published
- 2012
50. 707 Vibration Control in Wide Frequency Region by Parametric Excitation of Pendulum and Rotation of Hula-Hoop
- Author
-
Humiya Miyagawa, Yutaka Yoshitake, Akira Harada, Shuhei Kajihara, and Ryosuke Shimizu
- Subjects
Physics ,Dynamic Vibration Absorber ,Vibration isolation ,Torsional vibration ,business.industry ,Vibration control ,Pendulum ,Structural engineering ,business ,Rotation ,Excitation ,Parametric statistics - Published
- 2012
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