# Welcome

Ikuta Rikizo's web site.

# Profile Private

Name Rikizo Ikuta
E-mail ikuta@mp.es.osaka-u.ac.jp
Affiliation Imoto Laboratory,
Division of Materials Physics,
Department of Materials Engineering Science,
Graduate School of Engineering Science,
Osaka University
Research interests Quantum information processing
Quantum communication
Quantum optics
Academic society The Physical Society of Japan
The Japan Society of Applied Physics
My daughters
 2000-2003 anne (win98/FreeBSD) Solo2150, Gateway 12.1 inchMEM 64MB, HDD 6GB 2003-2013 anne (win2000/FreeBSD) homebuilt MEM 256MB, HDD 250GB 2005-2010 sala (winXP) Let's note R3, Panasonic 10.4 inchPentium(R) M 1.1GHz, MEM 256MB, HDD 40GB 2006-2011 diana (winXP) homebuilt 2010/6-2015/10 (snow leopard -> yosemite) macbook pro MC374J/A 13.3 inch Core 2 duo 2.4GHz, MEM 4GB, HDD 256GB 2012/4- nanaka (win7) Lenovo 1185-5XJ Core i5 3GHz, MEM 4GB, HDD 500GB 2015/11- himeragi (yosemite) macbook air (Early 2015) 13 inch Core i5 1.6GHz, MEM 4GB, SSD 128GB

# Papers

2016
1. 14. November. 2016

Motoki Asano, Konstantin Y. Bliokh, Yury P. Bliokh, Abraham G. Kofman, Rikizo Ikuta, Takashi Yamamoto, Yuri S. Kivshar, Lan Yang, Nobuyuki Imoto, Sahin Kaya Ozdemir, and Franco Nori,
Anomalous time delays and quantum weak measurements in optical micro-resonators'',
Nature Communications 7, 13488 (2016).

Quantum weak measurements, wavepacket shifts and optical vortices are universal wave phenomena, which originate from fine interference of multiple plane waves. These effects have attracted considerable attention in both classical and quantum wave systems. Here we report on a phenomenon that brings together all the above topics in a simple one-dimensional scalar wave system. We consider inelastic scattering of Gaussian wave packets with parameters close to a zero of the complex scattering coefficient. We demonstrate that the scattered wave packets experience anomalously large time and frequency shifts in such near-zero scattering. These shifts reveal close analogies with the Goos–Hänchen beam shifts and quantum weak measurements of the momentum in a vortex wavefunction. We verify our general theory by an optical experiment using the near-zero transmission (near-critical coupling) of Gaussian pulses propagating through a nano-fibre with a side-coupled toroidal micro-resonator. Measurements demonstrate the amplification of the time delays from the typical inverse-resonator-linewidth scale to the pulse-duration scale.

2. 31. October. 2016

Rikizo Ikuta, Toshiki Kobayashi, Kenichiro Matsuki, Shigehito Miki, Taro Yamashita, Hirotaka Terai, Takashi Yamamoto, Masato Koashi, Tetsuya Mukai, and Nobuyuki Imoto,
Heralded single excitation of atomic ensemble via solid-state-based telecom photon detection'',
Optica 3, 1279 (2016).

Telecom photonic quantum networks with matter quantum systems enable a rich variety of applications, such as long-distance quantum cryptography and one-way quantum computing. Preparation of a heralded single excitation (HSE) in an atomic ensemble by detecting a telecom wavelength photon having a correlation with the atomic excitation is an important step. Such a system has been demonstrated with a quantum frequency conversion (QFC) to telecom wavelength employing a Rb atomic cloud. However, the limited wavelength selection prevents the next step toward linking various kinds of matter quantum systems through long-distance fiber-based quantum communications. Here we for the first time, demonstrate HSE with a solid-state-based QFC and a detector for a telecom wavelength that will have the great advantage of the utility of mature telecom technologies. We unambiguously show that the demonstrated HSE indicates non-classical statistics by the direct measurement of the autocorrelation function.

3. 24. August. 2016

Yasutaka Imai, Tatsuya Nishi, Masatoshi Nishizaki, Sho Kawajiri, Yuto Muroki, Rikizo Ikuta, Kai Matsumoto, Masao Kitano, and Kazuhiko Sugiyama,
Single-ion spectroscopy system for the 2S1/2(F = 0) − 2D3/2(F = 2) transition in 171Yb+'',
Radio Science 51 (2016).

We report on our system and scheme for single-ion spectroscopy of the 2S1∕2(F=0) - 2D3∕2(F=2) clock transition in 171Yb+. Spectroscopy of the clock transition requires decoupling of the 2D3∕2(F = 2) state from the laser cooling cycle. We investigate this decoupling of the 2D3∕2(F = 2) state by using independent light sources for driving of all the transitions between the hyperfine structures contained in the cooling and repumping transitions. We observe the carrier spectrum of the mF = 0 − mF′ = 0 magnetic-insensitive transition with a spectral width of 380 Hz.

4. 14. July. 2016

Motoki Asano, Yuki Takeuchi, Weijian Chen, Sahin Kaya Ozdemir, Rikizo Ikuta, Lan Yang, Nobuyuki Imoto, and Takashi Yamamoto,
Observation of optomechanical coupling in a microbottle resonator'',
Laser & Photonics Reviews 10, 603 (2016).

In this work, we report optomechanical coupling, resolved sidebands and phonon lasing in a solid-core microbottle resonator fabricated on a single mode optical fiber. Mechanical modes with quality factors (Qm) as high as 1.57 × 104 and 1.45 × 104 were observed, respectively, at the mechanical frequencies inline image and inline image. The maximum inline image Hz is close to the theoretical lower bound of 6 × 1012 Hz needed to overcome thermal decoherence for resolved-sideband cooling of mechanical motion at room temperature, suggesting microbottle resonators as a possible platform for this endeavor. In addition to optomechanical effects, scatter-induced mode splitting and ringing phenomena, which are typical for high-quality optical resonances, were also observed in a microbottle resonator.

5. 25. May. 2016

Motoki Asano, Yuki Takeuchi, Sahin Kaya Ozdemir, Rikizo Ikuta, Lan Yang, Nobuyuki Imoto, and Takashi Yamamoto,
Stimulated Brillouin scattering and Brillouin-coupled four-wave-mixing in a silica microbottle　resonator'',
Opt. Express 24, 12082 (2016).

We report the first observation of stimulated Brillouin scattering (SBS) with Brillouin lasing, and Brillouin-coupled four-wave-mixing (FWM) in an ultra-high-Q silica microbottle resonator. The Brillouin lasing was observed at the frequency of ΩB = 2π × 10.4 GHz with a threshold power of 0.45 mW. Coupling between Brillouin and FWM was observed in both backward and forward scattering directions with separations of 2ΩB. At a pump power of 10 mW, FWM spacing reached to 7th and 9th order anti-Stokes and Stokes, respectively.

6. 6. May. 2016

Motoki Asano, Sahin Kaya Ozdemir, Weijian Chen, Rikizo Ikuta, Lan Yang, Nobuyuki Imoto, and Takashi Yamamoto,
Controlling slow and fast light and dynamic pulse-splitting with tunable optical gain in a whispering-gallery-mode microcavity'',
Appl. Phys. Lett. 108, 181105 (2016).

We report controllable manipulation of slow and fast light in a whispering-gallery-mode microtoroid resonator fabricated from Erbium (Er3+) dopedsilica. We observe continuous transition of the coupling between the fiber-taper waveguide and the microresonator from undercoupling to critical coupling and then to overcoupling regimes by increasing the pump power even though the spatial distance between the resonator and the waveguide was kept fixed. This, in turn, enables switching from fast to slow light and vice versa just by increasing the optical gain. An enhancement of delay of two-fold over the passive silicaresonator (no optical gain) was observed in the slow light regime. Moreover, we show dynamic pulse splitting and its control in slow/fast light systems using optical gain.

7. 4. May. 2016

Yuki Takeuchi, Keisuke Fujii, Rikizo Ikuta, Takashi Yamamoto, and Nobuyuki Imoto,
Blind quantum computation over a collective-noise channel'',
Phys. Rev. A 93, 052307 (2016), quant-ph/arXiv:1505.04248 (2015).

Blind quantum computation (BQC) allows a client (Alice), who only possesses relatively poor quantum devices, to delegate universal quantum computation to a server (Bob) in such a way that Bob cannot know Alice's inputs, algorithm, and outputs. The quantum channel between Alice and Bob is noisy, and the loss over the long-distance quantum communication should also be taken into account. Here we propose to use decoherence-free subspace (DFS) to overcome the collective noise in the quantum channel for BQC, which we call DFS-BQC. We propose three variations of DFS-BQC protocols. One of them, a coherent-light-assisted DFS-BQC protocol, allows Alice to faithfully send the signal photons with a probability proportional to a transmission rate of the quantum channel. In all cases, we combine the ideas based on DFS and the Broadbent-Fitzsimons-Kashefi protocol, which is one of the BQC protocols, without degrading unconditional security. The proposed DFS-based schemes are generic and hence can be applied to other BQC protocols where Alice sends quantum states to Bob.

8. 18. April. 2016

Toshiki Kobayashi, Rikizo Ikuta, Shuto Yasui, Shigehito Miki, Taro Yamashita, Hirotaka Terai, Takashi Yamamoto, Masato Koashi, and Nobuyuki Imoto,
Frequency-domain Hong-Ou-Mandel interference'',
Nature Photonics 10, 441 (2016), quant-ph/arXiv:1601.00739 (2016).

Hong-Ou-Mandel (HOM) interference unveils a distinct behavior of identical particles which cannot be distinguished from each other. Especially for bosons, two separated identical particles passing through a beamsplitter always go together into one of the output ports, but that is not the case with other particles including fermions or classical ones. So far many elemental properties of quantum physics and information have been discovered through the concatenated HOM effects, which has been demonstrated in photons and recently in plasmons, atoms and phonons. However, all demonstrations in optical region employed two particles in different spatial modes. Here we first report the HOM interference between two photons in a single spatial mode with different frequencies (energies) by using a partial frequency conversion. The demonstrated frequency-domain interferometer allows us to replace spatial optical paths by optical frequency multiplexing, which opens up a distinct architecture of the quantum interferometry.

9. 18. April. 2016

Yuichi Nagamatsu, Akihiro Mizutani, Rikizo Ikuta, Takashi Yamamoto, Nobuyuki Imoto, and Kiyoshi Tamaki,
Security of quantum key distribution with light sources that are not independently and identically distributed'',
Phys. Rev. A 93, 042325 (2016), quant-ph/arXiv:1602.02914 (2016).

Although quantum key distribution (QKD) is theoretically secure, there is a gap between the theory and practice. In fact, real-life QKD may not be secure because component devices in QKD systems may deviate from the theoretical models assumed in security proofs. To solve this problem, it is necessary to construct the security proof under realistic assumptions on the source and measurement unit. In this paper, we prove the security of a QKD protocol under practical assumptions on the source that accommodate fluctuation of the phase and intensity modulations. As long as our assumptions hold, it does not matter at all how the phase and intensity distribute nor whether or not their distributions over different pulses are independently and identically distributed (I.I.D.). Our work shows that practical sources can be safely employed in QKD experiments.

2015
1. 16. December. 2015

Motoki Asano, Muriel Bechu, Mark Tame, Sahin Kaya Ozdemir, Rikizo Ikuta, Durdu O. Guney, Takashi Yamamoto, Lan Yang, Martin Wegener and Nobuyuki Imoto,
Distillation of photon entanglement using a plasmonic metamaterial'',
Scientific Reports 5, 18313 (2015), quant-ph/arXiv:1507.07948 (2015).

Plasmonics is a rapidly emerging platform for quantum state engineering with the potential for building ultra-compact and hybrid optoelectronic devices. Recent experiments have shown that despite the presence of decoherence and loss, photon statistics and entanglement can be preserved in single plasmonic systems. This preserving ability should carry over to plasmonic metamaterials, whose properties are the result of many individual plasmonic systems acting collectively, and can be used to engineer optical states of light. Here, we report an experimental demonstration of quantum state filtering, also known as entanglement distillation, using a metamaterial. We show that the metamaterial can be used to distill highly entangled states from less entangled states. As the metamaterial can be integrated with other optical components this work opens up the intriguing possibility of incorporating plasmonic metamaterials in on-chip quantum state engineering tasks.

2. 14. May. 2015

Yoshiaki Tsujimoto, Yukihiro Sugiura, Makoto Ando, Daisuke Katsuse, Rikizo Ikuta, Takashi Yamamoto, Masato Koashi, Nobuyuki Imoto,
Extracting an entangled photon pair from collectively decohered pairs at a telecommunication wavelength'',
Optics Express 23, 13545 (2015), quant-ph/arXiv:1404.2197 (2014).

We experimentally demonstrated entanglement extraction scheme by using photons at the telecommunication band for optical-fiber-based quantum communications. We generated two pairs of non-degenerate polarization entangled photons at 780 nm and 1551 nm by spontaneous parametric down-conversion and distributed the two photons at 1551 nm through a collective phase damping channel which gives the same amount of random phase shift on the two photons. Through local operation and classical communication, we extracted an entangled photon pair from two phase-disturbed photon pairs. An observed fidelity of the extracted photon pair to a maximally entangled photon pair was 0.73 ¥pm 0.07 which clearly shows the recovery of entanglement.

2014
1. 10. June. 2014

Akihiro Mizutani, Rikizo Ikuta, Kiyoshi Tamaki, Takashi Yamamoto, and Nobuyuki Imoto,
Measurement-device-independent quantum key distribution for Scarani-Acin-Ribordy-Gisin 04 protocol'',
Scientific Reports 4, 5236 (2014), quant-ph/arXiv:1404.2197 (2014).

The measurement-device-independent quantum key distribution (MDI QKD) was proposed to make BB84 completely free from any side-channel in detectors. Like in prepare & measure QKD, the use of other protocols in MDI setting would be advantageous in some practical situations. In this paper, we consider SARG04 protocol in MDI setting. The prepare & measure SARG04 is proven to be able to generate a key up to two-photon emission events. In MDI setting we show that the key generation is possible from the event with single or two-photon emission by a party and single-photon emission by the other party, but the two-photon emission event by both parties cannot contribute to the key generation. On the contrary to prepare & measure SARG04 protocol where the experimental setup is exactly the same as BB84, the measurement setup for SARG04 in MDI setting cannot be the same as that for BB84 since the measurement setup for BB84 in MDI setting induces too many bit errors. To overcome this problem, we propose two alternative experimental setups, and we simulate the resulting key rate. Our study highlights the requirements that MDI QKD poses on us regarding with the implementation of a variety of QKD protocols.

2. 5. May. 2014

Rikizo Ikuta, Toshiki Kobayashi, Shuto Yasui, Shigehito Miki, Taro Yamashita, Hirotaka Terai, Mikio Fujiwara, Takashi Yamamoto, Masato Koashi, Masahide Sasaki, Zhen Wang, and Nobuyuki Imoto,
Frequency down-conversion of 637 nm light to the telecommunication band for non-classical light emitted from NV centers in diamond'',
Optics Express 22, 11205 (2014), quant-ph/arXiv:1402.2944 (2013).

We demonstrate a low-noise frequency down-conversion of photons at 637 nm to the telecommunication band at 1587 nm by the difference frequency generation in a periodically-poled lithium niobate. An internal conversion efficiency of the converter is estimated to be 0.44 at the maximum which is achieved by a pump power of 0.43 W, whereas a rate of internal background photons caused by the strong cw pump laser is estimated to be 9 kHz/mW within a bandwidth of about 1 nm. By using the experimental values related to the intrinsic property of the converter, and using the intensity correlation and the average photon number of a 637 nm input light pulse, we derive the intensity correlation of a converted telecom light pulse. Then we discuss feasibility of a single-photon frequency conversion to the telecommunication band for a long-distance quantum communication based on NV centers in diamond.

3. 4. February. 2014

Toshiki Kobayashi, Rikizo Ikuta, Sahin Kaya Ozdemir, Mark Tame, Takashi Yamamoto, Masato Koashi, and Nobuyuki Imoto,
Universal gates for transforming multipartite entangled Dicke states'',
New Journal of Physics 16, 023005 (2014), quant-ph/arXiv:1305.1130 (2013).

We determine the minimal number of qubits that it is necessary to have access to in order to transform Dicke states into other Dicke states. In general, the number of qubits in Dicke states cannot be increased via transformation gates by accessing only a single qubit, in direct contrast to other multipartite entangled states such as GHZ, W and cluster states. We construct a universal optimal gate which adds spin-up qubits or spin-down qubits to any Dicke state by minimal access. We also show the existence of a universal gate which transforms any size of Dicke state as long as it has access to at least the required number of qubits. Our results have important consequences for the generation of Dicke states in physical systems such as ion traps, all-optical setups and cavity-QED settings where they can be used for a variety of quantum information processing tasks.

2013
1. 6. November. 2013

Rikizo Ikuta, Toshiki Kobayashi, Hiroshi Kato, Shigehito Miki, Taro Yamashita, Hirotaka Terai, Mikio Fujiwara, Takashi Yamamoto, Masato Koashi, Masahide Sasaki, Zhen Wang, and Nobuyuki Imoto,
Observation of two output light pulses from a partial wavelength converter preserving phase of an input light at a single-photon level'',
Optics Express 21, 27865 (2013), quant-ph/arXiv:1309.2761 (2013).

We experimentally demonstrate that both of the two output light pulses of different wavelengths from a wavelength converter with various branching ratios preserve phase information of an input light at a single-photon level. In our experiment, we converted temporally-separated two coherent light pulses with average photon numbers of $\sim 0.1$ at 780 nm to light pulses at 1522 nm by using difference-frequency generation in a periodically-poled lithium niobate waveguide. We observed an interference between temporally-separated two modes for both the converted and the unconverted light pulses at various values of the conversion efficiency. We observed interference visibilities greater than 0.88 without suppressing the background noises for any value of the conversion efficiency the wavelength converter achieves. At a conversion efficiency of $\sim 0.5$, the observed visibilities are 0.98 for the unconverted light and 0.99 for the converted light. Such a phase-preserving wavelength converter with high visibilities will be useful for manipulating quantum states encoded in the frequency degrees of freedom.

2. 14. October. 2013

Rikizo Ikuta, Toshiki Kobayashi, Hiroshi Kato, Shigehito Miki, Taro Yamashita, Hirotaka Terai, Mikio Fujiwara, Takashi Yamamoto, Masato Koashi, Masahide Sasaki, Zhen Wang, and Nobuyuki Imoto,
Nonclassical two-photon interference between independent telecommunication light pulses converted by difference-frequency generation'',
Phys. Rev. A 88, 042317 (2013), quant-ph/arXiv:1304.0304 (2013).

We experimentally demonstrated the Hong-Ou-Mandel (HOM) interference between two photons after visible-to-telecommunication wavelength conversion. In the experiment, we prepared a heralded single photon by using spontaneous parametric down-conversion and the other photon from a weak laser source at 780 nm. We converted the wavelength of both photons to the telecommunication wavelength of 1522 nm by using difference-frequency generation in a periodically-poled lithium niobate, and then observed the HOM interference between the photons. The observed visibility is $0.76\pm 0.12$ which clearly shows the non-classical interference of the two photons. The high-visibility interference is an important step for fiber-based quantum communications of photons generated from visible photon emitters.

3. 2. January. 2013

Rikizo Ikuta, Hiroshi Kato, Yoshiaki Kusaka, Shigehito Miki, Taro Yamashita, Hirotaka Terai, Mikio Fujiwara, Takashi Yamamoto, Masato Koashi, Masahide Sasaki, Zhen Wang, and Nobuyuki Imoto,
High-fidelity conversion of photonic quantum information to telecommunication wavelength with superconducting single-photon detectors'',
Phys. Rev. A 87, 010301(R) (2013), quant-ph/arXiv:1207.1585 (2012).

We experimentally demonstrate a high-fidelity visible-to-telecommunication wavelength conversion of a photon by using a solid-state-based difference frequency generation. In the experiment, one half of a pico-second visible entangled photon pair at 780 nm is converted to a 1522-nm photon, resulting in the entangled photon pair between 780 nm and 1522 nm. Using superconducting single-photon detectors with low dark count rates and small timing jitters, we selectively observed well-defined temporal modes containing the two photons. We achieved a fidelity of $0.93 \pm 0.04$ after the wavelength conversion, indicating that our solid-state-based scheme can be used for faithful frequency down-conversion of visible photons emitted from quantum memories composed of various media.

2011
1. Rikizo Ikuta, Yohei Ono, Toshiyuki Tashima, Takashi Yamamoto, Masato Koashi, and Nobuyuki Imoto,
Efficient and robust photonic entanglement distribution using decoherencefree subspace'',
AIP Conference Proceedings 1363, 263 (2011).

We propose and demonstrate a scheme for boosting up the efficiency of entanglement distribution based on a decoherence‐free subspace (DFS) over lossy quantum channels. Our scheme achieves an entanglement‐sharing rate that is proportional to the transmittance of the quantum channel in spite of encoding qubits in multipartite systems for the DFS.

2. Y. Tokunaga, S. Okamoto, Rikizo Ikuta, Takashi Yamamoto, Masato Koashi, and Nobuyuki Imoto,
Process tomography of elementary gates in optical oneway quantum computing'',
AIP Conference Proceedings 1363, 252 (2011).

We demonstrate quantum process tomography of experimental photonic one‐way quantum computing. We investigate one‐qubit rotation gates and the two‐qubit controlled‐phase gate and the process matrix is derived from the maximally likelihood estimation. From the completely reconstructed process matrices, we can evaluate several gate performances such as process fidelity, purity, and entanglement capability.

3. 15. November. 2011

Rikizo Ikuta, Yoshiaki Kusaka, Tsuyoshi Kitano, Hiroshi Kato, Takashi Yamamoto, Masato Koashi, and Nobuyuki Imoto,
Wide-band quantum interface for visible-to-telecommunication wavelength conversion'',
Nature Commun. 2, 537 (2011), quant-ph/arXiv:1106.1758 (2011).

We perform the first demonstration of a quantum interface for frequency down-conversion from visible to telecommunication bands by using a nonlinear crystal. This interface has a potential to work over wide bandwidths, leading to a high-speed interface of frequency conversion. We achieve the conversion of a pico-second visible photon at 780 nm to a 1522-nm photon, and observe that the conversion process retain entanglement between the down-converted photon and another photon.

4. 14. March. 2011

Rikizo Ikuta, Yohei Ono, Toshiyuki Tashima, Takashi Yamamoto, Masato Koashi, Nobuyuki Imoto,
Efficient decoherence-free entanglement distribution over lossy quantum channels'',
Phys. Rev. Lett. 106, 110503 (2011), arXiv:1012.5584.

We propose and demonstrate a scheme for boosting up the efficiency of entanglement distribution based on a decoherence-free subspace (DFS) over lossy quantum channels. By using backward propagation of a coherent light, our scheme achieves an entanglement-sharing rate that is proportional to the transmittance T of the quantum channel in spite of encoding qubits in multipartite systems for the DFS. We experimentally show that highly entangled states, which can violate the Clauser-Horne-Shimony-Holt inequality, are distributed at a rate proportional to T.

5. 24. January. 2011

Rikizo Ikuta, Toshiyuki Tashima, Takashi Yamamoto, Masato Koashi, Nobuyuki Imoto,
Optimal local expansion of W states using linear optics and Fock states",
Phys. Rev. A 83, 012314 (2011), arXiv:1004.0608.

We derive the maximum success probability of circuits with passive linear optics for postselectively expanding an N-photon W state to an (N+n)-photon W state, by accessing only one photon of the initial W state and adding n photons in a Fock state. We show that the maximum success probability is achieved by a polarization-dependent beamsplitter and n-1 polarization-independent beamsplitters.

# Conferences Memories (in Japanese)

International / Domestic
2016
1. 2016/7/4 - 8 : シンガポール シンガポール国立大学

街が思ったよりけっこう汚くてちょっと残念だった。食事もまあ普通。OCBCガーデンラプソディはけっこう良かったかなと。

Rikizo Ikuta, Toshiki Kobayashi, Kenichiro Matsuki, Shigehito Miki, Taro Yamashita, Hirotaka Terai, Takashi Yamamoto, Masato Koashi, Tetsuya Mukai, and Nobuyuki Imoto,
''Wavelength Conversion of non-classical light from rubidium atoms to the telecom band'' (poster),
2016/7/4 - 8
13th International Conference on Quantum Communication, Measurement, and Computing (QCMC 2016),
National University of Singapore, Singapore.

2013
1. 2013/8/25 - 30 : インド チェンナイ

まだ薄もやがかかりひっそりと静まり返った明け方に、怒りモードの野犬数匹に吠えられ追いかけられるという悲惨な目に遭った。きゃつらの前で走ってはいけないという重要なことを学んだ。

Rikizo Ikuta, Toshiki Kobayashi, Hiroshi Kato, Shigehito Miki, Taro Yamashita, Hirotaka Terai, Mikio Fujiwara, Takashi Yamamoto, Masato Koashi, Masahide Sasaki, Zhen Wang, and Nobuyuki Imoto,
''Non-classical interference between two telecom photons converted by difference-frequency generation'' (oral),
2013/8/25 - 30
13th Asian Quantum Information Science Conference (AQIS 2013),
The institute of mathematical sciences, Chennai, India.

2. 2013/4/4 - 12 : 奈良県 新公会堂

広々とした公園、満開の桜、雲ひとつない快晴のお天気。とても気持ちよく散歩ができて大変楽しかった。また行きたい。

Rikizo Ikuta,
''Non-classical two-photon interference between telecom light pulses converted by difference-frequency generation'' (poster),
2013/4/4 - 12
The 11th US-Japan Joint Seminar on Quantum Electronics and Laser Spectroscopy "Ultimate Quantum Systems of Light and Matter- Control and Applications",
Nara Prefectural New Public Hall, Nara, Japan.

2012
1. 2012/7/30 - 8/3 : オーストリア ウィーン ウィーン工科大学

いかにもヨーロッパ風の町並みで散歩しているだけで楽しい。ザッハトルテおいしい。シュニッツェルもおいしい。料理は全般においしかった。

Rikizo Ikuta, Hiroshi Kato, Yoshiaki Kusaka, Shigehito Miki, Taro Yamashita, Hirotaka Terai, Mikio Fujiwara, Takashi Yamamoto, Masato Koashi, Masahide Sasaki, Zhen Wang, and Nobuyuki Imoto,
''High-fidelity frequency down-conversion of visible entangled photon pairs with superconducting single-photon detectors'' (poster),
2012/7/30 - 8/3
QCMC 2012 The Eleventh International Conference on Quantum Communication, Measurement and Computation,
Vienna University of Technology, Vienna, Austria.

2011
1. 2011/8/24 - 27 : 韓国 釜山 釜慶大学校

とりあえず量が多いので、 勿体無いと思わずに思い切って残すようにした方が無難。 味はまあ普通。

Rikizo Ikuta, Yoshiaki Kusaka, Tsuyoshi Kitano, Hiroshi Kato, Takashi Yamamoto, Masato Koashi, and Nobuyuki Imoto,
''Wide-band quantum interface for visible-to-telecommunication wavelength conversion'' (oral),
2011/8/24 - 27
11th Asian Quantum Information Science Conference (AQIS 2011), Pukyong National University, Busan, Korea.

2. 2011/5/1 - 6 : アメリカ ボルチモア コンベンションセンター

クラブケーキは絶品。

Rikizo Ikuta, Tsuyoshi Kitano, Yoshiaki Kusaka, Takashi Yamamoto, Masato Koashi, and Nobuyuki Imoto,
Frequency down-conversion of non-classical light from visible wavelength to telecom wavelength using difference-frequency generation'' (poster),
2011/5/1 - 6
the Conference on Lasers and Electro-Optics (CLEO: 2011), Baltimore Convention Center, Baltimore, Maryland, USA.

2010
1. 2010/7/19 - 23 : オーストラリア ブリスベン クイーンズランド大学

エクスカージョンでコアラやカンガルーと戯れるなどした。

Rikizo Ikuta, Yohei Ono, Toshiyuki Tashima, Takashi Yamamoto, Masato Koashi, and Nobuyuki Imoto,
Efficient and robust photonic entanglement distribution using decoherence-free subspace'', (poster)
QCMC 2010 The Tenth International Conference on Quantum Communication, Measurement and Computation
2010/7/19 - 23
University of Queensland, Brisbane, Queensland, Australia.

2. 2010/5/30 - 6/4 : 日本 大阪大学

Rikizo Ikuta, Yohei Ono, Toshiyuki Tashima, Takashi Yamamoto, Masato Koashi, and Nobuyuki Imoto,
Efficient and robust photonic entanglement distribution using decoherence-free subspace'', (poster)
International Conference on Core Research and Engineering Science of Advanced Materials (Global COE Program)
Third International Conference on Nanospintronics Design and Realization (3rd-ICNDR)
2010/5/30 - 6/4
Osaka University, Convention Center, Osaka, Japan.

2009
1. 2009/9/1 - 9/3 : 日本 大阪大学

Rikizo Ikuta, Toshiyuki Tashima, Takashi Yamamoto, Masato Koashi, and Nobuyuki Imoto,
Efficiency improvement of local expansion of W states using linear optics'', (poster)
5th Handai Nanoscience and Nanotechnology International Symposium
2009/9/1 - 9/3
Osaka University, Japan.

2. 2009/8/24 - 8/27 : カナダ トロント大学

慣れた味の食事を採る事ができて夜も比較的安全で、海外不慣れな人間にはとてもいい街。

Rikizo Ikuta, Toshiyuki Tashima, Takashi Yamamoto, Masato Koashi, and Nobuyuki Imoto,
Local expansion of W states using linear optics'', (poster)
The 3rd Conference on Quantum Information and Quantum Control (CQIQCIII)
2009/8/24 - 8/27
Fields Institute, Toronto, Canada.

2016
1. 2016/5/30 - 31 : 高知工科大学 永国寺キャンパス

神会議。あらゆる食事がおいしすぎて力が漲る。

生田力三, 野崎正太, 山本俊, 小芦雅斗, 井元信之,
“Experimental demonstration of robust entanglement distribution over reciprocal channels assisted by a counter-propagating light” (口頭, 発表日 5/31),
第34回量子情報技術研究会 (QIT34),
2016/5/30 - 31,
高知工科大学 永国寺キャンパス.

2. 2016/3/19 - 22 : 東京工業大学 大岡山キャンパス

初めての東工大。とてもいい場所だった。うちとは大違い。 そして Kaila、すごくおいしかった。

生田力三, 野崎正太, 山本俊, 小芦雅斗, 井元信之,
“雑音のある reciprocal 通信路を介したエンタングルメント配送実験” (口頭, 発表日 3/20),
2016年第63回応用物理学会春季学術講演会 20p-W541-4,
2016/3/19 - 22,
東京工業大学 大岡山キャンパス.

2014
1. 2014/9/7 - 10 : 愛知県 中部大学 春日井キャンパス

名古屋名物三昧な食事で非常に満足。

生田力三, 小林俊輝, 加藤大織, 三木茂人, 山下太郎, 寺井弘高, 藤原幹生, 山本俊, 小芦雅斗, 佐々木雅英, 王鎮, 井元信之,
"微弱コヒーレント光を用いた入力光の位相を保持する部分波長変換器の実証実験", (口頭, 発表日 9/9),
日本物理学会第68回年次大会 9aAZ-2,
2014/9/7-10,
中部大学 春日井キャンパス.

2. 2014/3/17 - 20 : 神奈川県 青山学院大学 相模原キャンパス

大学の建物の中にエスカレーターがあった。

生田力三, 山本俊, 小芦雅斗, 井元信之,
"分極反転デバイスの量子中継への応用", (招待講演, 発表日 3/18),
2014年第61回応用物理学会春季学術講演会 18p-F8-6,
2014/3/17 - 20,
青山学院大学 相模原キャンパス.

2013
1. 2013/9/17 - 20 : 福岡 福岡工業大学

もつ鍋がおいしい。

生田力三, 山本俊, 小芦雅斗, 井元信之,
"単一光子の波長変換を利用した量子操作", (招待講演)
電子通信学会2013年ソサイエティ大会,
2013/9/17 - 20,
福岡工業大学.

2. 2013/5/27 - 28 : 北海道 北海道大学 札幌キャンパス

ミルク村は神。

生田力三, Sahin K. Ozdemir, Mark Tame, 田嶌俊之, 山本俊, 小芦雅斗, 井元信之,
"A ferro-spin filter for photonic polarization qubits", (ポスター)
第28回量子情報技術研究会 (QIT28),
2013/5/27 - 28,
北海道大学 札幌キャンパス.

3. 2013/3/26 - 29 : 広島県 広島大学 東広島キャンパス

駅から遠すぎて大変だった。もみじまんじゅうはいつ食べてもおいしい。

生田力三, 小林俊輝, 加藤大織, 三木茂人, 山下太郎, 寺井弘高, 藤原幹生, 山本俊, 小芦雅斗, 佐々木雅英, 王鎮, 井元信之,
"可視域から通信波長帯へ周波数下方変換された二光子の非古典的干渉の観測", (口頭, 発表日3/26）,
日本物理学会第68回年次大会 26aED-2,
2013/3/26 - 3/29,
広島大学 東広島キャンパス（東広島市鏡山 2-313）.

2012
1. 2012/12/12 - 15 : 東京大学小柴ホール

何一つ記憶にない。

生田力三, 日下良章, 北野剛史, 加藤大織, 山本俊, 小芦雅斗, 井元信之,
"High-fidelity visible-to-telecommunication wavelength conversion with superconducting single-photon detectors and non-classical interference using wavelength-converted two photons", (ポスター, 発表日12/14)
FIRSTプロジェクト全体会議2012,
2012/12/12 - 15,
東京大学小柴ホール.

2. 2012/6/21 - 22 : 京都府 ハイアットリージェンシー京都

朝食のバイキングがおいしくて、おかげで快適に一日が始められる。

R. Ikuta, H. Kato, Y. Kusaka, S. Miki, T. Yamashita, H. Terai, M. Fujiwara, T. Yamamoto, M. Koashi, M. Sasaki, Z. Wang, and N. Imoto,
"High-fidelity wavelength conversion of a quantum state with a superconducting single photon detector", (ポスター)
第7回量子サイバネティクス総括班会議会,
2012/6/21 - 6/22,
ハイアットリージェンシー京都.

3. 2012/3/24 - 27 : 兵庫県 関西学院大学 上ヶ原キャンパス

ここのキャンパスはとても綺麗で癒される。あと、甲東園は、甲子園、昭和園、甲風園、甲陽園、苦楽園、香櫨園、と並んで西宮七園と呼ばれ、七英雄みたいでかっこいい。

生田力三, 加藤大織, 日下良章, 三木茂人, 山下太郎, 寺井弘高, 藤原幹生, 山本俊, 小芦雅斗, 佐々木雅英, 王鎮, 井元信之,
"超伝導単一光子検出器を用いた量子状態の高忠実度波長変換実験", (口頭)
日本物理学会2012年春季大会 24pBE-4,
2012/3/24 - 3/27,
関西学院大学 上ヶ原キャンパス.

2011
1. 2011/12/13 - 16 : 京都府 京都国際ホテル

とり安の親子丼うまかった。

生田力三, 日下良章, 北野剛史, 加藤大織, 山本俊, 小芦雅斗, 井元信之,
"Wide-band quantum interface for visible-to-telecommunication wavelength conversion", (ポスター)
FIRSTプロジェクト全体会議2011,
2011/12/13 - 16,
京都国際ホテル.

2. 2011/11/21 - 22 : 大阪府 大阪大学豊中キャンパス

何の面白味もない土地。

生田力三, 日下良章, 北野剛史, 加藤大織, 山本俊, 小芦雅斗, 井元信之,
"Photonic quantum interface for visible-to-telecommunication wavelength conversion", (口頭)
第25回量子情報技術研究会 (QIT25),
2011/11/21 - 22,
大阪大学 基礎工学研究科 国際棟 （豊中キャンパス）.

3. 2011/9/21 - 24 : 富山県 富山大学五福キャンパス

富山駅付近は居酒屋ばっかり。居酒屋だいの食事は非常においしかった。

生田力三, 日下良章, 北野剛史, 加藤大織, 山本俊, 小芦雅斗, 井元信之,
"可視域エンタングルメント光子対の周波数下方変換実験", (口頭)
日本物理学会2011年秋季大会21pED-9,
2011/9/21 - 9/24,
富山大学 五福キャンパス.

2010
1. 2011/3/25 - 28 : 新潟大学

震災のため、現地入りせず。

生田力三, 北野剛史, 日下良章, 山本俊, 小芦雅斗, 井元信之,
"可視域から通信波長域への非古典光の周波数下方変換実験", (口頭扱い)
日本物理学会2011年春季大会26pRB-5,
2011/3/25 - 3/28,
新潟大学.

2. 2010/12/8 - 11 : 静岡県 ホテルニューフジヤ熱海

特定の人を除いて何度も来るような場所ではない。

生田力三, 小野陽平, 田嶌俊之, 山本俊, 小芦雅斗, 井元信之,
"Efficiency improvement of faithful entanglement distribution using decoherence-free subspace", (ポスター)
量子情報処理プロジェクト全体会議2010,
2010/12/8 - 11,
ホテルニューフジヤ熱海.

3. 2010/10/28 - 30 : 岡山県 瀬戸内市 岡山いこいの村

食事がとても残念。初日昼に出た、具なしで少量のカレーの手抜き具合は衝撃の域。

生田力三,
"Efficient and robust photonic entanglement distribution using decoherence-free subspace", (口頭)
平成22年度 G－COE若手秋の学校「量子物性の解明と新機能」,
2010/10/28 - 30,
岡山いこいの村（岡山県瀬戸内市）.

4. 2010/9/28 : 情報通信研究機構 神戸研究所

懇親会で出た食事が思いのほか豪華だった。

生田力三, 北野剛史, 日下良章, 山本俊, 小芦雅斗, 井元信之,
"可視域から通信波長域への非古典光の周波数下方変換の実現", (ポスター)
第 5 回 KARC-Σ連携セミナー,
2010/9/28,
情報通信研究機構神戸研究所.

5. 2010/9/23 - 9/26 : 大阪府立大学

駅から大学に行く途中にあるたこやき屋が安い。

生田力三, 小野陽平, 田嶌俊之, 山本俊, 小芦雅斗, 井元信之,
R "DFSを用いたエンタングルメント配送の高効率化", (口頭)
日本物理学会2010年秋季大会,
2010/9/23 - 8/26,
大阪府立大学.

6. 2010/8/18 - 28 : 沖縄県 ホテルサンライズ知念

生まれて初めて海水浴なるものをした。沖縄の海は実にきれい。街にも優良な店が多くて楽しい。

生田力三, 小野陽平, 田嶌俊之, 山本俊, 小芦雅斗, 井元信之,
"DFSを用いたエンタングルメント配送の高効率化", (ポスター)
最先端研究開発支援プログラム「量子情報処理プロジェクト」夏期研修会 (第 1 回),
2010/8/18 - 8/28,
ホテルサンライズ知念.

2009
1. 2009/11/4 - 5 : 電気通信大学

関東出身の偉い人曰く、「くずもち」といえば、葛餅ではなく久寿餅が普通らしい。

生田力三, 田嶌俊之, 山本俊, 小芦雅斗, 井元信之,
"Optimal local expansion of W states using linear optics and Fock states", (ポスター)
第20回量子情報技術研究会 (QIT21),
2009/11/4 - 5,
電気通信大学.

2. 2009/9/25 - 9/28 : 熊本大学 黒髪キャンパス

馬肉はおいしい。

生田力三, 田嶌俊之, 山本俊, 小芦雅斗, 井元信之,
"線形光学素子を用いた局所操作によるW状態拡張ゲートの効率化", (口頭)
日本物理学会2009年秋季大会25aZF-4,
2009/9/25 - 3/28,
熊本大学黒髪キャンパス.

3. 2009/9/14 - 16 : 滋賀県 休暇村 近江八幡

実は琵琶湖をちゃんと見たのは初めてで、まあまあ良かった。

生田力三,
"線形光学素子を用いた局所操作によるW状態拡張ゲートの効率化", (ポスター)
平成21年度 G-COE若手秋の学校「新しい量子物質・物性・機能の研究」,
2009/9/14-16,
休暇村 近江八幡（滋賀県）.

4. 2009/6/12 - 13 : 大阪大学 豊中キャンパス

生田力三, 田嶌俊之, 山本俊, 小芦雅斗, 井元信之,
"線形光学素子を用いた局所操作によるW状態拡張ゲートの効率化", (ポスター)
第 6 回　原子・分子・光化学（AMO）討論会,
2009/6/12 - 6/13,
大阪大学 豊中キャンパス Σホール.

2005
1. 2005/5/19 : 金沢大学

21世紀美術館は面白い。朝市も楽しい。あと、駅がなかなか美しい。とてもいい街。

生田力三, 北野正雄, 杉山和彦,
"Yb+時計遷移用半導体レーザの開発", (口頭)
電子情報通信学会.