Magnetic quantum defects in a uniaxial antiferromagnetic insulator

Abstract

Point defects have been successfully utilized in various quantum technologies, serving as quantum qubits for quantum computation, single-photon emitters for quantum communication, and nanoscale sensors for quantum metrology. However, their further development faces key challenges, particularly in discovering and exploring suitable defect-host systems that meet the necessary criteria for quantum applications. Here, using polarization-resolved Raman spectroscopy and terahertz absorption spectroscopy, we discover three distinct chromium-vacancy-induced excitations in the uniaxial antiferromagnetic insulator, Cr₂O₃. These vacancy-induced excitations have an energy scale of a few tens of millielectronvolts and are twofold degenerate, and the lowest one at 64 cm⁻¹ is sharp and sensitive to the external magnetic field along the easy-axis direction, particularly close to the spin-flop regime around 6T, where the mode softens from 64 to 27cm⁻¹. Based on the defect supercell first-principles calculations, we interpret the mode at 64 cm⁻¹ as a local magnetic excitation of the local moment within the chromium vacancy state. Our results establish that the magnetic defect states in Cr₂O₃ have potential for quantum applications.

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Cite

BibTeX RIS

BibTeX

@misc{wu2026magnetic,
  title = {{Magnetic quantum defects in a uniaxial antiferromagnetic insulator}},
  author = {Shangfei Wu and Laur Peedu and Zhihao Wang and Xuecong Wang and Xianghan Xu and Kai Du and Sang-Wook Cheong and Aleksei Boldin and Joosep Link and Ivo Heinmaa and Raivo Stern and Sai Mu and Urmas Nagel and Toomas Rõõm and Girsh Blumberg},
  howpublished = {arXiv},
  year = {2026},
  month = sep,
  doi = {10.48550/arxiv.2609.00801},
  eprint = {2609.00801},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2609.00801},
}

RIS

TY  - UNPB
TI  - Magnetic quantum defects in a uniaxial antiferromagnetic insulator
AU  - Shangfei Wu
AU  - Laur Peedu
AU  - Zhihao Wang
AU  - Xuecong Wang
AU  - Xianghan Xu
AU  - Kai Du
AU  - Sang-Wook Cheong
AU  - Aleksei Boldin
AU  - Joosep Link
AU  - Ivo Heinmaa
AU  - Raivo Stern
AU  - Sai Mu
AU  - Urmas Nagel
AU  - Toomas Rõõm
AU  - Girsh Blumberg
PY  - 2026
DA  - 2026/09/01
PB  - arXiv
DO  - 10.48550/arxiv.2609.00801
UR  - https://arxiv.org/abs/2609.00801
AB  - Point defects have been successfully utilized in various quantum technologies, serving as quantum qubits for quantum computation, single-photon emitters for quantum communication, and nanoscale sensors for quantum metrology. However, their further development faces key challenges, particularly in discovering and exploring suitable defect-host systems that meet the necessary criteria for quantum applications. Here, using polarization-resolved Raman spectroscopy and terahertz absorption spectroscopy, we discover three distinct chromium-vacancy-induced excitations in the uniaxial antiferromagnetic insulator, Cr_2O_3. These vacancy-induced excitations have an energy scale of a few tens of millielectronvolts and are twofold degenerate, and the lowest one at 64 cm^−1 is sharp and sensitive to the external magnetic field along the easy-axis direction, particularly close to the spin-flop regime around 6T, where the mode softens from 64 to 27cm^−1. Based on the defect supercell first-principles calculations, we interpret the mode at 64 cm^−1 as a local magnetic excitation of the local moment within the chromium vacancy state. Our results establish that the magnetic defect states in Cr_2O_3 have potential for quantum applications.
ER  -

Abstract

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