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Two-step spin decoherence in transition metal dichalcogenide defect qubits
Taejoon Park1,2, Jaewook Lee1,2, Huijin Park1,2
1SKKU Advanced Institute of Nanotechnology, Sungkyunkwan University, Suwon, Gyeonggi 16419, Republic of Korea. seo.hosung@skku.edu.
Materials Horizons
|August 7, 2026
Summary
Two-dimensional transition metal dichalcogenides (TMDCs) exhibit early coherence collapse (ECC) in defect qubits, limiting coherence to microseconds. This early collapse, driven by nuclear spin dynamics, is a key decoherence factor in TMDC qubits.
Area of Science:
- Quantum computing materials science
- Solid-state physics
- Defect physics
Background:
- Two-dimensional transition metal dichalcogenides (TMDCs) are explored as qubit hosts due to low nuclear spin density.
- Theoretical predictions suggest millisecond coherence times for ideal TMDC qubits under specific magnetic fields.
- The influence of defect structure and magnetic fields on TMDC qubit decoherence is not well understood.
Purpose of the Study:
- Investigate spin decoherence mechanisms in specific TMDC defect qubit candidates.
- Analyze the impact of varying magnetic field strengths on qubit coherence.
- Determine the role of defect type and host material in decoherence.
Main Methods:
- Utilized hybrid density functional theory (DFT) combined with cluster correlation expansion (CCE).
- Simulated spin decoherence for carbon radical ion (S=1/2) and antisite defects (S=1).
- Examined decoherence under a range of magnetic field strengths.
Main Results:
- Observed early collapse of coherence (ECC) on a sub-microsecond timescale for TMDC defect qubits.
- Identified a two-step decoherence process: initial ECC followed by slower decay.
- Mo-based TMDCs showed pronounced ECC, with coherence suppressed at specific magnetic fields.
- ECC was identified as a dominant decoherence mechanism, influenced by nuclear spin dynamics.
Conclusions:
- Early coherence collapse (ECC) is a critical factor limiting qubit coherence in TMDCs.
- Defect characteristics and nuclear spin environment significantly impact TMDC qubit performance.
- Understanding ECC is crucial for developing robust TMDC-based quantum bits.
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