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Measuring reliable electron spin coherence times with dynamical decoupling sequences that use selective mw pulses
George Mitrikas1, Rania Giourtsidou2
1Institute of Nanoscience and Nanotechnology, NCSR Demokritos, Athens 15310, Greece.
Journal of Magnetic Resonance (San Diego, Calif. : 1997)
|October 9, 2025
Summary
Dynamical decoupling sequences like CPMG, XY4, and XY8 are crucial for measuring electron spin coherence times (T2). This study reveals microwave pulse selectivity issues that can skew T2 measurements, offering a simulation-based solution.
Area of Science:
- Quantum Information Science
- Magnetic Resonance Spectroscopy
- Condensed Matter Physics
Background:
- Dynamical decoupling sequences, including Carr-Purcell-Meiboom-Gill (CPMG), XY4, and XY8, are essential for measuring electron spin coherence times (T2).
- These methods aim to mitigate decoherence sources but often overlook the impact of microwave pulse (mw) selectivity.
- Pulse selectivity can lead to overestimated T2 values due to overlapping stimulated echoes and artificial decay in echo amplitudes.
Purpose of the Study:
- To investigate the impact of microwave pulse selectivity on dynamical decoupling sequences.
- To analyze the characteristics of CPMG, XY4, and XY8 sequences concerning pulse selectivity.
- To develop a simulation-based method for accurate T2 determination, accounting for pulse imperfections and relaxation.
Main Methods:
- Numerical simulations of a two-level spin system were performed.
- The Liouville space representation was used to model the spin state.
- Relaxation effects were incorporated into the simulations to mimic experimental conditions.
Main Results:
- Simulations accurately reproduced experimental echo features.
- The study identified how mw pulse selectivity affects echo amplitudes and T2 measurements.
- A method was demonstrated to accurately determine T2 times by accounting for pulse selectivity and relaxation.
Conclusions:
- Microwave pulse selectivity is a critical, often overlooked, factor in T2 measurements using dynamical decoupling.
- Numerical simulations provide a powerful tool to understand and correct for these effects.
- The proposed simulation approach enables accurate T2 determination without complex experimental phase-cycling protocols.
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