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Deterministic Bell state measurement with a single quantum memory 0000-0001-5465-2352 Kamimaki, Akira Institute for Advanced Sciences (IAS), Yokohama National University Quantum Information Research Center (QIC), Yokohama National University 0009-0000-8917-2527 Wakamatsu, Keidai Department of Physics, Graduate School of Engineering Science, Yokohama National University Mikata, Kosuke Department of Physics, Graduate School of Engineering Science, Yokohama National University 0000-0002-8850-4646 Sekiguchi, Yuhei Institute for Advanced Sciences (IAS), Yokohama National University Quantum Information Research Center (QIC), Yokohama National University 0000-0002-3778-7236 20361199 Kosaka, Hideo Institute for Advanced Sciences (IAS), Yokohama National University Quantum Information Research Center (QIC), Yokohama National University open access Creative Commons Attribution 4.0 International Quantum information, Quantum optics Entanglements serve as a resource for any quantum information system and are deterministically generated or swapped by a joint measurement called complete Bell state measurement (BSM). The determinism arises from a quantum nondemolition measurement of two coupled qubits with the help of readout ancilla, which inevitably requires extra physical qubits. We here demonstrate a deterministic and complete BSM with only a nitrogen atom in a nitrogen-vacancy (NV) center in diamond as a quantum memory without relying on any carbon isotopes, which are the extra qubits, by exploiting electron‒nitrogen (14N) double qutrits at a zero magnetic field. The degenerate logical qubits within the subspace of qutrits on the electron and nitrogen spins are holonomically controlled by arbitrarily polarized microwave and radiofrequency pulses via zero-field-split states as the ancilla, thus enabling the complete BSM deterministically. Since the system works under an isotope-free and field-free environment, the demonstration paves the way to realize high-fidelity quantum repeaters for long-haul quantum networks and quantum interfaces for large-scale distributed quantum computers. Springer Nature 2023-10-16 eng journal article VoR http://hdl.handle.net/10131/0002000121 https://ynu.repo.nii.ac.jp/records/2000121 https://doi.org/10.1038/s41534-023-00771-z 20566387 npj Quantum Information 9 https://ynu.repo.nii.ac.jp/record/2000121/files/20231016_Deterministic Bell state measurement with a single quantum.pdf application/pdf 2.7 MB 2023-10-26 2023-10-16