T
Takahide Umeda
Researcher at University of Tsukuba
Publications - 78
Citations - 2192
Takahide Umeda is an academic researcher from University of Tsukuba. The author has contributed to research in topics: Vacancy defect & Electron paramagnetic resonance. The author has an hindex of 21, co-authored 76 publications receiving 2000 citations. Previous affiliations of Takahide Umeda include National Institute of Advanced Industrial Science and Technology & NEC.
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Journal ArticleDOI
Hybrid Quantum Circuit with a Superconducting Qubit Coupled to a Spin Ensemble
Yuimaru Kubo,Cecile Grezes,A. Dewes,Takahide Umeda,Junichi Isoya,Hitoshi Sumiya,Norio Morishita,Hiroshi Abe,Shinobu Onoda,Takeshi Ohshima,Vincent Jacques,A. Dréau,Jean-François Roch,Igor Diniz,Alexia Auffèves,Denis Vion,Daniel Esteve,Patrice Bertet +17 more
TL;DR: Using a hybrid quantum circuit combining a superconducting qubit and an ensemble of electronic spins, a superposition of the qubit states is prepared that is stored into collective excitations of the spin ensemble and retrieved back into the qubits later on.
Journal ArticleDOI
Negative-U System of Carbon Vacancy in 4H-SiC
Nguyen Tien Son,Xuan Thang Trinh,Lars Løvlie,Bengt Gunnar Svensson,Koutarou Kawahara,Jun Suda,Tsunenobu Kimoto,Takahide Umeda,Junichi Isoya,Takahiro Makino,Takeshi Ohshima,Erik Janzén +11 more
TL;DR: Using EPR and deep-level transient spectroscopy, it is shown that the two most common defects in as-grown 4H-SiC--the Z(1/2) lifetime-limiting defect and the EH(7) deep defect--are related to the double acceptor and single donor levels of V(C), respectively.
Journal ArticleDOI
Divacancy in 4H-SiC.
Nguyen Tien Son,Patrick Carlsson,J. ul Hassan,Erik Janzén,Takahide Umeda,Junichi Isoya,Adam Gali,Michel Bockstedte,Norio Morishita,Takeshi Ohshima,Hisayoshi Itoh +10 more
TL;DR: Electron paramagnetic resonance and ab initio supercell calculations suggest that the P6/P7 centers, which were previously assigned to the photoexcited triplet states of the carbon vacancy-antisite pairs in the double positive charge state, are related to the triplet groundStates of the neutral divacancy.
Journal ArticleDOI
Extending spin coherence times of diamond qubits by high-temperature annealing
Takashi Yamamoto,Takahide Umeda,Kenji Watanabe,Shinobu Onoda,Matthew Markham,Daniel J. Twitchen,Boris Naydenov,Liam P. McGuinness,Tokuyuki Teraji,Satoshi Koizumi,Florian Dolde,Helmut Fedder,Jan Honert,Jörg Wrachtrup,Takeshi Ohshima,Fedor Jelezko,Junichi Isoya +16 more
TL;DR: In this article, the authors demonstrate that a high-temperature annealing at 1000 √ √ C allows 2 ms coherence times to be achieved at room temperature for spin-carrying nitrogen-vacancy defects in a single crystal chemical vapor deposited diamond.
Posted Content
Multi-mode storage and retrieval of microwave fields in a spin ensemble
Cecile Grezes,Brian Julsgaard,Yuimaru Kubo,Michael Stern,Takahide Umeda,Junichi Isoya,Hitoshi Sumiya,Hiroshi Abe,Shinobu Onoda,Takeshi Ohshima,Vincent Jacques,Jérôme Estève,Denis Vion,Daniel Esteve,Klaus Mølmer,Patrice Bertet +15 more
TL;DR: In this article, an active reset of nitrogen-vacancy (NV) spins into their ground state by optical pumping and their refocusing by Hahn echo sequences is presented, enabling the storage of multiple microwave pulses at the picoWatt level and their retrieval after up to $35 \mu$s.