Dispersive measurement of spin shot noise in a Bose-Einstein condensate

Kosuke Shibata, Naota Sekiguchi, Junnosuke Takai, Takuya Hirano

Physical Review Research, Oct 14, 2025
Multistate interferometric measurement of the nonlinear ac Stark shift

Junnosuke Takai, Kosuke Shibata, Naota Sekiguchi, Takuya Hirano

Physical Review A, May 11, 2023
Highly efficient measurement of optical quadrature squeezing using a spatial light modulator controlled by machine learning

Jorge Amari, Junnosuke Takai, Takuya Hirano

Optics Continuum, Apr 15, 2023
Improved waveguide-based ultraviolet light generation and pulsed squeezing at 795 nm

Aki Torii, Kosuke Shibata, Yujiro Eto, Takuya Hirano

Optics Express, 30(15) 26120-26120, Jul 18, 2022 Peer-reviewed

We report on the waveguide-based generation of pulsed squeezed light at 795 nm, suitable for quantum enhanced measurements with rubidium atoms. Pulsed ultraviolet second harmonic light with a power of more than 400 mW is produced using a periodically poled LiNbO₃ (PPLN) waveguide and is injected into another PPLN waveguide to generate quadrature squeezing. We find that the phase of the second harmonic pulse is shifted within a pulse, and we attribute the shift to heating due to blue-light induced infrared absorption (BLIIRA) from a comparison between the experiment and a numerical simulation. A squeezing level of −1.5(1) dB is observed in homodyne detection when we apply a linear phase shift to the local oscillator. The experiment and simulation imply that the squeezing level can be further improved by reducing BLIIRA.
Sensitive spatially resolved magnetometry using a Bose-condensed gas with a bright probe

Naota Sekiguchi, Kosuke Shibata, Aki Torii, Hiroyuki Toda, Ryohei Kuramoto, Daiki Fukuda, Takuya Hirano

Physical Review A, 104(4), Oct 28, 2021 Peer-reviewed
Effect of cascaded nonlinear phase shift on pulsed second-harmonic generation using periodically poled waveguide: a comparison of experimental and numerical results

Yujiro Eto, Takuya Hirano

Japanese Journal of Applied Physics, 60(5), May, 2021 Peer-reviewed
Quantum lock-in detection of a vector light shift

Kosuke Shibata, Naota Sekiguchi, Takuya Hirano

Physical Review A, 103(4), Apr, 2021 Peer-reviewed
Challenges in Coding, DSP and Parallel Operation of Quantum Key Distribution and Coherent Data Transmission

Tobias A. Eriksson, Ruben S. Luis, Georg Rademacher, Benjamin J. Puttnam, Kadir Gumus, Laurent Schmalen, Alex Alvarado, Hideaki Furukawa, Naoya Wada, Takuya Hirano, Masahide Sasaki, Masahiro Takeoka

2020 European Conference on Optical Communications, ECOC 2020, Dec, 2020
Compensation of gravity on cold atoms by a linear optical potential

Kosuke Shibata, Hidehiko Ikeda, Ryota Suzuki, Takuya Hirano

Physical Review Research, 2(1), Jan, 2020 Peer-reviewed
Faraday patterns generated by Rabi oscillation in a binary Bose-Einstein condensate

Terun Chen, Kosuke Shibata, Yujiro Eto, Takuya Hirano, Hiroki Saito

Physical Review A, 100(6), Dec, 2019 Peer-reviewed
Interaction modulation in a long-lived Bose-Einstein condensate by rf coupling

Shibata K, Torii A, Shibayama H, Eto Y, Saito H, Hirano T

Physical Review A, 99(1), 2019 Peer-reviewed
Dissipation-Assisted Coherence Formation in a Spinor Quantum Gas

Eto Y, Shibayama H, Shibata K, Torii A, Nabeta K, Saito H, Hirano T

Physical Review Letters, 122(24), 2019 Peer-reviewed
Wavelength division multiplexing of continuous variable quantum key distribution and 18.3 Tbit/s data channels

Eriksson, T.A., Hirano, T., Puttnam, B.J., Rademacher, G., Lu{\'i}s, R.S., Fujiwara, M., Namiki, R., Awaji, Y., Takeoka, M., Wada, N., Sasaki, M.

Communications Physics, 2(1), 2019 Peer-reviewed
Pulse-resolved measurement of continuous-variable Einstein-Podolsky-Rosen entanglement with shaped local oscillators

Shinjo A, Eto Y, Hirano T

Optics Express, 27(13) 17610-17619, 2019 Peer-reviewed
Secret key rate of a continuous-variable quantum-key-distribution scheme when the detection process is inaccessible to eavesdroppers

Ryo Namiki, Akira Kitagawa, Takuya Hirano

Physical Review A, 98(4), Oct, 2018 Peer-reviewed
Spinor dynamics in a mixture of spin-1 and spin-2 Bose-Einstein condensates

Yujiro Eto, Hitoshi Shibayama, Hiroki Saito, Takuya Hirano

Physical Review A, 97(2), Feb 13, 2018 Peer-reviewed
Ground-state phases of a mixture of spin-1 and spin-2 Bose-Einstein condensates

Naoki Irikura, Yujiro Eto, Takuya Hirano, Hiroki Saito

Physical Review A, 97(2), Feb 13, 2018 Peer-reviewed
Time-Domain Measurement of Continuous-Variable Entanglement Using Temporally Shaped Local Oscillator Pulses

Shinjo A, Eto Y, Hirano T

IEEE Photonics Society Summer Topicals Meeting Series, SUM 2018, 111-112, 2018 Peer-reviewed
Secure transmission using QAM quantum noise stream cipher with continuous variable QKD

Masataka Nakazawa, Masato Yoshida, Takuya Hirano

Optics InfoBase Conference Papers, 2018 1-3, 2018 Peer-reviewed
Joint Propagation of Continuous Variable Quantum Key Distribution and 18 × 24.5 Gbaud PM-16QAM Channels

Eriksson T.A, Hirano T, Rademacher G, Puttnam B.J, Lu{\'i}s R.S, Fujiwara M, Namiki R, Awaji Y, Takeoka M, Wada N, Sasaki M

European Conference on Optical Communication, ECOC, 2018-September, 2018 Peer-reviewed
Secret key rate of a continuous-variable quantum-key-distribution scheme when the detection process is inaccessible to eavesdroppers

Namiki R, Kitagawa A, Hirano T

Physical Review A, 98(4), 2018 Peer-reviewed
Coexistence of Continuous Variable Quantum Key Distribution and 7×12.5 Gbit/s Classical Channels

Eriksson T.A, Hirano T, Ono M, Fujiwara M, Namiki R, Yoshino K.-I, Tajima A, Takeoka M, Sasaki M

IEEE Photonics Society Summer Topicals Meeting Series, SUM 2018, 73-74, 2018 Peer-reviewed
Pulse-resolved measurement of continuous-variable EPR entanglement with shaped local oscillators

Shinjo A, Katayama T, Eto Y, Hirano T

Optics InfoBase Conference Papers, Part F125-JSAP 2018, 2018 Peer-reviewed
Non-equilibrium dynamics induced by miscible-immiscible transition in binary Bose-Einstein condensates (vol 18, 073029, 2016)

Eto Yujiro, Takahashi Masahiro, Kunimi Masaya, Saito Hiroki, Hirano Takuya

New Journal of Physics, 20, 2018 Peer-reviewed
Bouncing motion and penetration dynamics in multicomponent Bose-Einstein condensates (vol 93, 033615, 2016)

Yujiro Eto, Masahiro Takahashi, Keita Nabeta, Ryotaro Okada, Masaya Kunimi, Hiroki Saito, Takuya Hirano

PHYSICAL REVIEW A, 96(6), Dec, 2017 Peer-reviewed
Notes on a Continuous-Variable Quantum Key Distribution Scheme

Tsubasa Ichikawa, Takuya Hirano, Takuto Matsubara, Motoharu Ono, Ryo Namiki

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 86(9), Sep, 2017 Peer-reviewed
QAM Quantum Noise Stream Cipher Transmission Over 100 km With Continuous Variable Quantum Key Distribution

Masataka Nakazawa, Masato Yoshida, Toshihiko Hirooka, Keisuke Kasai, Takuya Hirano, Tsubasa Ichikawa, Ryo Namiki

IEEE JOURNAL OF QUANTUM ELECTRONICS, 53(4), Aug, 2017 Peer-reviewed
Implementation of continuous-variable quantum key distribution with discrete modulation

Takuya Hirano, Tsubasa Ichikawa, Takuto Matsubara, Motoharu Ono, Yusuke Oguri, Ryo Namiki, Kenta Kasai, Ryutaroh Matsumoto, Toyohiro Tsurumaru

Quantum Science and Technology, 2(2), Jun 1, 2017 Peer-reviewed
Phase separation of Rabi-coupled spin states in an⁸⁷Rb F = 1 BEC

Shibata K, Shibayama H, Torii A, Suzuki R, Toda H, Eto Y, Takahashi M, Saito H, Hirano T

Optics InfoBase Conference Papers, Part F78-JSAP 2017, 2017 Peer-reviewed
Phase separation dynamics of two-component bose-einstein condensates in various optical trap shapes

Shibayama H, Torii A, Shibata K, Eto Y, Saito H, Hirano T

Optics InfoBase Conference Papers, Part F78-JSAP 2017, 2017 Peer-reviewed
Observation of self-organized coherence in dissipative spinor Bose-Einstein condensates

Eto Y, Shibayama H, Torii A, Saito H, Hirano T

Optics InfoBase Conference Papers, Part F78-JSAP 2017, 2017 Peer-reviewed
Nonequilibrium dynamics induced by miscible-immiscible transition in binary Bose-Einstein condensates

Yujiro Eto, Masahiro Takahashi, Masaya Kunimi, Hiroki Saito, Takuya Hirano

NEW JOURNAL OF PHYSICS, 18 073029, Jul, 2016 Peer-reviewed
Bouncing motion and penetration dynamics in multicomponent Bose-Einstein condensates

Yujiro Eto, Masahiro Takahashi, Keita Nabeta, Ryotaro Okada, Masaya Kunimi, Hiroki Saito, Takuya Hirano

PHYSICAL REVIEW A, 93(3) 033615, Mar, 2016 Peer-reviewed
Cold atom magnetometers

Yujiro Eto, Mark Sadrove, Takuya Hirano

Lecture Notes in Physics, 911 111-133, 2016 Peer-reviewed
Real-time 70 Gbit/s, 128 QAM quantum noise stream cipher transmission over 100 km with secret keys delivered by continuous variable quantum key distribution system

Nakazawa M, Yoshida M, Hirooka T, Kasai K, Hirano T

European Conference on Optical Communication, ECOC, 887-889, 2016 Peer-reviewed
Observation of strong continuous-variable Einstein-Podolsky-Rosen entanglement using shaped local oscillators

Ami Shinjo, Naoyuki Hashiyama, Akane Koshio, Yujiro Eto, Takuya Hirano

QUANTUM INFORMATION SCIENCE AND TECHNOLOGY II, 9996, 2016 Peer-reviewed
Generation of physical random numbers by using homodyne detection

Kodai Hirakawa, Shota Oya, Yusuke Oguri, Tsubasa Ichikawa, Yujiro Eto, Takuya Hirano, Toyohiro Tsurumaru

QUANTUM INFORMATION SCIENCE AND TECHNOLOGY II, 9996, 2016 Peer-reviewed
Continuous operation of four-state continuous-variable quantum key distribution system

Takuto Matsubara, Motoharu Ono, Yusuke Oguri, Tsubasa Ichikawa, Takuya Hirano, Kenta Kasai, Ryutaroh Matsumoto, Toyohiro Tsurumaru

QUANTUM INFORMATION SCIENCE AND TECHNOLOGY II, 9996, 2016 Peer-reviewed
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, 5, Aug, 2015 Peer-reviewed
Suppression of relative flow by multiple domains in two-component Bose-Einstein condensates

Yujiro Eto, Masaya Kunimi, Hidekatsu Tokita, Hiroki Saito, Takuya Hirano

PHYSICAL REVIEW A, 92(1) 013611, Jul, 2015 Peer-reviewed
Control of spin current in a Bose gas by periodic application of pi pulses

Yujiro Eto, Mark Sadgrove, Sho Hasegawa, Hiroki Saito, Takuya Hirano

PHYSICAL REVIEW A, 90(1) 013626, Jul, 2014 Peer-reviewed
Observation of Dipole-Induced Spin Texture in an Rb-87 Bose-Einstein Condensate

Yujiro Eto, Hiroki Saito, Takuya Hirano

PHYSICAL REVIEW LETTERS, 112(18) 185301, May, 2014 Peer-reviewed
Ramsey Interferometry Using the Zeeman Sublevels in a Spin-2 Bose Gas

Mark Sadgrove, Yujiro Eto, Sawako Sekine, Hirosuke Suzuki, Takuya Hirano

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 82(9) 094002, Sep, 2013 Peer-reviewed
Spin-echo-based magnetometry with spinor Bose-Einstein condensates

Yujiro Eto, Hayato Ikeda, Hirosuke Suzuki, Sho Hasegawa, Yasushi Tomiyama, Sawako Sekine, Mark Sadgrove, Takuya Hirano

PHYSICAL REVIEW A, 88(3) 031602, Sep, 2013 Peer-reviewed
Control and detection of the larmor precession of f = 2 87rb bose-einstein condensates by ramsey interferometry and spin-echo

Yujiro Eto, Sawako Sekine, Sho Hasegawa, Mark Sadgrove, Hiroki Saito, Takuya Hirano

Applied Physics Express, 6(5) 052801, May, 2013 Peer-reviewed
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, 52(4) 048001, Apr, 2013 Peer-reviewed
Collective Excitation of Bose-Einstein Condensates Induced by Evaporative Cooling

Takeshi Kuwamoto, Takuya Hirano

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 81(7) 074002, Jul, 2012 Peer-reviewed
Quantum entanglement generating system and method, and quantum entanglement generating and detecting system and method

Hirano Takuya, Eto Yujiro

Jul, 2012 Peer-reviewed

US Patent 8,228,507
Quantum cryptography communication method, quantum cryptography communication apparatus, and quantum cryptography communication system

Kawamoto Yohei, Namiki Ryo, Hirano Takuya

May, 2012 Peer-reviewed

US Patent 8,175,273
Quantum cryptography communication apparatus and communication terminal

Kawamoto Yohei, Hirano Takuya, Shino Kuninori, Ukita Masakazu

Apr, 2012 Peer-reviewed

US Patent 8,165,298

Misc.

240

光直交振幅変調による量子暗号通信

平野琢也, 並木亮, 中沢正隆, 吉田真人, 廣岡俊彦, 葛西恵介

応用物理学会春季学術講演会講演予稿集(CD-ROM), 64th, 2017
Multi-Level Ramsey Interferometry Using m_F=0 State in a Spin-2 Bose-Einstein Condensate

Nabeta Keita, Okada Ryotaro, Torii Aki, Sadgrove Mark, Shibayama Hitoshi, Eto Yujiro, Hirano Takuya

Meeting Abstracts of the Physical Society of Japan, 71 511-511, 2016

<p>我々は以前からスピン2ボース・アインシュタイン凝縮体のスピン制御技術を利用して、ラムゼイ干渉によりラーモア歳差運動の観測をしてきた。これまでは、初期状態が磁気副準位m_F_=2の状態で実験を行ってきたが、初期状態を適切に選ぶことで干渉計の感度を向上させることが予測されている。本発表ではm_F_=0を初期状態にした時のラジオ波によるスピンの回転とラムゼイ干渉について報告する。</p>
Non-equilibrium dynamics induced by miscibility control in binary Bose-Einstein condensates

Eto Yujiro, Takahashi Masahiro, Kunimi Masaya, Saito Hiroki, Hirano Takuya

Meeting Abstracts of the Physical Society of Japan, 71 505-505, 2016

<p>多成分流体の空間的な構造形成は、非平衡過程や非線型現象を理解する上で重要な効果である。我々は、2成分ボース・アインシュタイン凝縮体の混和性を制御することにより、不安定な空間構造を持つ混ざり合う性質の2成分凝縮体を生成し、パターン形成ダイナミクスを観測することに成功した。発表では、混和性制御の方法や実験結果の詳細について紹介する。</p>
21pBJ-4 Real-time key generation using high-speed continuous variable Quantum key distribution system 2

Matsubara T, Ono M, Ichikawa T, Hirano T, Kasai K, Matsumoto R, Tsurumaru T

Meeting Abstracts of the Physical Society of Japan, 71 746-746, 2016
19aBK-10 Rabi Oscillation between Zeeman States in ^<87>Rb Bose-Einstein Condensate

Okada R, Nabeta K, Torii A, Takahashi M, Eto Y, Kunimi M, Saito H, Hirano T

Meeting Abstracts of the Physical Society of Japan, 71 632-632, 2016

Books and Other Publications

Cold Atom Magnetometers, in Principles and Methods of Quantum Information Technologies

Yujiro Eto, Mark Sadrove, Takuya Hirano (Role: Joint author)

Springer Japan, 2016
光科学研究の最前線２分担執筆 I-1-2「非古典的光」

国際文献印刷社, 2009
基礎からの量子光学監修：(社)応用物理学会量子エレクトロニクス研究会, 松岡正浩、江馬一弘、平野琢也、岩本敏

オプトロニクス社, 2009 (ISBN: 9784902312423)
量子情報通信「コヒーレント光とホモダイン検波による量子鍵配送」,p.179-204

オプトロニクス社, 2006
物理学大事典，第１４章「量子光学」

朝倉書店, 2005

Professional Memberships

Works

Research Projects

空間位相変調器を用いた量子状態の高効率測定

科学研究費助成事業, 日本学術振興会, Apr, 2019 - Mar, 2023

平野琢也
Information communication technology ensuring the long term security over a century

Grants-in-Aid for Scientific Research, Japan Society for the Promotion of Science, Jun, 2018 - Mar, 2023
Broadcast continuous variable quantum key distribution

Grants-in-Aid for Scientific Research, Japan Society for the Promotion of Science, Apr, 2018 - Mar, 2021

Takeoka Masahiro
Non-equilibrium Dynamics in Multi-component Bose-Einstein Condensates

Grants-in-Aid for Scientific Research, Japan Society for the Promotion of Science, Jun, 2013 - Mar, 2018

Hirano Takuya, TAKAHASHI Masahiro, ETO Yujiro, SHIBATA Kosuke
Synergy of Fluctuation and Structure : Quest for Universal Laws in Non-Equilibrium Systems

Grants-in-Aid for Scientific Research, Japan Society for the Promotion of Science, Jun, 2013 - Mar, 2018

SANO Masaki, SASA Shin-ichi, ORIHARA Hiroshi, IMAI Masayuki, KOMURA Shigeyuki, KIMURA Yasuyuki, HIRANO Takuya, ICHIKAWA Masatoshi, MIYAZAKI Kunimasa, YOSHIKAWA Kenichi, SAKURAI Tatsunari, KOBAYASHI Kensuke

Industrial Property Rights

特開2017-050678 光秘匿通信システム

中沢正隆, 吉田真人, 廣岡俊彦, 平野琢也
特許第5041256号量子エンタングルメント生成装置及び方法並びに量子エンタングルメント生成検出装置及び方法

平野琢也, 衛藤雄二郎
特許第4962700号量子暗号通信装置

川元洋平, 平野琢也, 篠邦宣, 浮田昌一
特許第4936157号量子暗号通信方法及び量子暗号通信装置

平野琢也
特許第4838166号量子暗号通信装置および通信端末

川元洋平, 平野琢也, 篠邦宣, 浮田昌一

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