Article
Optics
Ayato Okada, Rekishu Yamazaki, Maria Fuwa, Atsushi Noguchi, Yuya Yamaguchi, Atsushi Kanno, Naokatsu Yamamoto, Yuji Hishida, Hirotaka Terai, Yutaka Tabuchi, Koji Usami, Yasunobu Nakamura
Summary: This paper reports the development of a superconducting acousto-optic phase modulator on a lithium niobate substrate, with electrodes made of a superconducting niobium titanium nitride thin film for improved device performance. Operating at a cryogenic temperature, a length-half-wave-voltage product of 1.78 V.cm was observed, with further enhancement of modulation efficiency tested through an optical cavity with mirror coating. Simulation suggests that a simple extension of the current device could achieve efficient modulation with V-pi = 0.27 V.
Article
Physics, Applied
Caglar Kutlu, Arjan F. van Loo, Sergey Uchaikin, Andrei N. Matlashov, Doyu Lee, Seonjeong Oh, Jinsu Kim, Woohyun Chung, Yasunobu Nakamura, Yannis K. Semertzidis
Summary: This paper reports on the operation of a flux-driven Josephson parametric amplifier (JPA) operating at around 2.3 GHz with added noise approaching the quantum limit. By operating the JPA at a gain of 19 dB and cascading it with two cryogenic amplifiers operating at 4 K, noise temperatures as low as 120 mK were achieved for the whole signal detection chain.
SUPERCONDUCTOR SCIENCE & TECHNOLOGY
(2021)
Article
Quantum Science & Technology
K. Shulga, I Vakulchyk, Y. Nakamura, S. Flach, M. Fistul
Summary: Numerical evidence is provided for the existence of time molecules (TMs), which exhibit periodic temporal interference in the dynamics of two interacting qubits subject to pi-pulses. The TMs have specific characteristics such as almost zero total polarization, enhanced entanglement entropy, and switching between maximally entangled states. These phenomena are stable with detuned system parameters and can also be observed in dynamics of three interacting qubits.
QUANTUM SCIENCE AND TECHNOLOGY
(2021)
Editorial Material
Engineering, Electrical & Electronic
Koji Usami, Yasunobu Nakamura
Summary: A superconducting electromechanical device at cryogenic temperatures can be detected using optical fibres and a commercial phase modulator.
NATURE ELECTRONICS
(2021)
Article
Engineering, Electrical & Electronic
A. V. Chumak, P. Kabos, M. Wu, C. Abert, C. Adelmann, A. O. Adeyeye, J. Akerman, F. G. Aliev, A. Anane, A. Awad, C. H. Back, A. Barman, G. E. W. Bauer, M. Becherer, E. N. Beginin, V. A. S. V. Bittencourt, Y. M. Blanter, P. Bortolotti, I. Boventer, D. A. Bozhko, S. A. Bunyaev, J. J. Carmiggelt, R. R. Cheenikundil, F. Ciubotaru, S. Cotofana, G. Csaba, O. V. Dobrovolskiy, C. Dubs, M. Elyasi, K. G. Fripp, H. Fulara, I. A. Golovchanskiy, C. Gonzalez-Ballestero, P. Graczyk, D. Grundler, P. Gruszecki, G. Gubbiotti, K. Guslienko, A. Haldar, S. Hamdioui, R. Hertel, B. Hillebrands, T. Hioki, A. Houshang, C. -M. Hu, H. Huebl, M. Huth, E. Iacocca, M. B. Jungfleisch, G. N. Kakazei, A. Khitun, R. Khymyn, T. Kikkawa, M. Klaui, O. Klein, J. W. Klos, S. Knauer, S. Koraltan, M. Kostylev, M. Krawczyk, I. N. Krivorotov, V. V. Kruglyak, D. Lachance-Quirion, S. Ladak, R. Lebrun, Y. Li, M. Lindner, R. Macedo, S. Mayr, G. A. Melkov, S. Mieszczak, Y. Nakamura, H. T. Nembach, A. A. Nikitin, S. A. Nikitov, V. Novosad, J. A. Otalora, Y. Otani, A. Papp, B. Pigeau, P. Pirro, W. Porod, F. Porrati, H. Qin, B. Rana, T. Reimann, F. Riente, O. Romero-Isart, A. Ross, A. V. Sadovnikov, A. R. Safin, E. Saitoh, G. Schmidt, H. Schultheiss, K. Schultheiss, A. A. Serga, S. Sharma, J. M. Shaw, D. Suess, O. Surzhenko, K. Szulc, T. Taniguchi, M. Urbanek, K. Usami, A. B. Ustinov, T. van der Sar, S. van Dijken, V. I. Vasyuchka, R. Verba, S. Viola Kusminskiy, Q. Wang, M. Weides, M. Weiler, S. Wintz, S. P. Wolski, X. Zhang
Summary: Magnonics is a discipline that explores the physical properties of spin waves and utilizes them for data processing. It offers several advantages, such as scalability to atomic dimensions, operation in high-frequency ranges, utilization of nonlinear and nonreciprocal phenomena, and compatibility with CMOS technology. Although primarily in the academic domain, extensive research is being conducted to address the scientific and technological challenges, with several proof-of-concept prototypes already realized in laboratories.
IEEE TRANSACTIONS ON MAGNETICS
(2022)
Article
Multidisciplinary Sciences
Kirill G. Fedorov, Michael Renger, Stefan Pogorzalek, Roberto Di Candia, Qiming Chen, Yuki Nojiri, Kunihiro Inomata, Yasunobu Nakamura, Matti Partanen, Achim Marx, Rudolf Gross, Frank Deppe
Summary: Researchers have successfully demonstrated unconditional quantum teleportation of propagating coherent microwave states over a distance of 0.42 meters using two-mode squeezing and analog feedforward, achieving a teleportation fidelity of 0.689, surpassing the asymptotic no-cloning threshold.
Article
Physics, Applied
Imran Mahboob, Hiraku Toida, Kousuke Kakuyanagi, Yasunobu Nakamura, Shiro Saito
Summary: The experiment achieved high gain by implementing a Josephson parametric amplifier (JPA) in a three-wave mixing configuration in a three-dimensional microwave cavity, coupled to a superconducting quantum interference device (SQUID) embedded in a two-dimensional resonator.
APPLIED PHYSICS EXPRESS
(2022)
Article
Engineering, Electrical & Electronic
Shuhei Tamate, Yutaka Tabuchi, Yasunobu Nakamura
Summary: This paper reviews the basic components of superconducting quantum computers, with a focus on the packaging and wiring technologies required for large-scalable superconducting quantum computers.
IEICE TRANSACTIONS ON ELECTRONICS
(2022)
Article
Physics, Applied
Y. Sunada, S. Kono, J. Ilves, S. Tamate, T. Sugiyama, Y. Tabuchi, Y. Nakamura
Summary: This study demonstrates the suppression of resonator-mediated qubit decay by utilizing the distributed-element, multimode nature of the resonator. Using this method, high-fidelity readout and reset operations can be achieved.
PHYSICAL REVIEW APPLIED
(2022)
Review
Physics, Multidisciplinary
Babak Zare Rameshti, Silvia Viola Kusminskiy, James A. Haigh, Koji Usami, Dany Lachance-Quirion, Yasunobu Nakamura, Can-Ming Hu, Hong X. Tang, Gerrit E. W. Bauer, Yaroslav M. Blanter
Summary: Cavity magnonics explores the interaction between magnons and confined electromagnetic fields, offering strong magnon-photon coupling and nonlinear behavior in microwave cavities. This field has the potential to be integrated into future quantum technologies. Magnetic optical resonators enhance the interaction between magnons and light, enabling magnon cooling and heating. The coupling between a magnon mode and a superconducting qubit in a microwave cavity allows for measurements in the single magnon limit.
PHYSICS REPORTS-REVIEW SECTION OF PHYSICS LETTERS
(2022)
Article
Engineering, Electrical & Electronic
Shigeyuki Miyajima, Taro Yamashita, Masamitsu Tanaka, Naoki Takeuchi, Kunihiro Inomata, Hirotaka Terai
Summary: We developed a process for monolithically integrating nitride superconductor-based superconducting qubits with SFQ-based readout and control circuits. The device structure consists of three superconductive layers, including a Josephson junction made of an NbN/AlN/NbN tri-layer. We successfully fabricated a JJ with a low leakage current and a J(c) of around 50 A/cm(2), and the evaluated sheet inductance exceeded 1 pH.
IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY
(2023)
Article
Physics, Applied
Tsuyoshi Takahashi, Norinao Kouma, Yoshiyasu Doi, Shintaro Sato, Shuhei Tamate, Yasunobu Nakamura
Summary: This study reveals that the junction-resistance of Al/AlOx/Al Josephson structures can be affected by the metal deposition during shadow evaporation, and a two-step shadow evaporation method is introduced to reduce the resistance variation, which shows promise for the development of large-scale superconducting quantum computers.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2023)
Article
Materials Science, Multidisciplinary
Hiroki Ikegami, Yasunobu Nakamura
Summary: This research presents experimental investigations of transport properties in the insulating phase of two-dimensional Josephson-junction arrays (JJAs). The results indicate that the JJAs exhibit nonlinear current-voltage characteristics at low temperatures, and the crossover temperature to the insulating phase and the phase diagram in the insulating side are determined through the analysis of nonlinearity.
Article
Quantum Science & Technology
Yoshifumi Nakata, Da Zhao, Takayuki Okuda, Eiichi Bannai, Yasunari Suzuki, Shiro Tamiya, Kentaro Heya, Zhiguang Yan, Kun Zuo, Shuhei Tamate, Yutaka Tabuchi, Yasunobu Nakamura
Summary: Unitary t-design is a powerful tool in quantum information science and fundamental physics. This paper provides quantum circuits that generate exact unitary t-designs for any number of qubits, and introduces a tth-order generalization of randomized benchmarking as an application of exact 2t-designs. The study shows that the 2-RB can be used to characterize background noise of superconducting qubits, but interactions with adjacent qubits may pose obstacles towards quantum error correction.
