arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2003.02171quant-phcond-mat.other
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含时磁场中CPMG序列绝热和非绝热行为的观测

Observation of adiabatic and non-adiabatic behavior for CPMG sequence in time-dependent magnetic fields

Martin D. Hürlimann, Shin Utsuzawa, Chang-Yu Hou

摘要:

实验研究了含时磁场对Carr - Purcell - Meiboom - Gill(CPMG)序列自旋动力学的影响.在宽范围的偏移场和斜坡率,测量的响应是完全一致的绝热行为。回波幅度表现出与理论预测非常一致的特征调制。在不同的偏移量处观察到非绝热事件。经过这些偏移后,实验结果突然偏离理论绝热表达式。这些非绝热事件精确地发生在理论预测的场偏移处。结果表明,在绝热状态下,场涨落的影响是完全可逆的,而非绝热事件的发生导致滞后。场偏移的绝热范围可以通过修改CPMG序列内的重聚焦脉冲来增加。

英文摘要:

We investigate experimentally the effect of time dependent magnetic fields on the spin dynamics of the Carr - Purcell - Meiboom - Gill (CPMG) sequence. Over a wide range of offset fields and ramp rates, the measured response is fully consistent with adiabatic behavior. The echo amplitudes exhibit characteristic modulations that are in excellent agreement with theoretical predictions. Non-adiabatic events are observed at distinct offsets. Abruptly after passing through these offsets, the experimental results deviate from the theoretical adiabatic expressions. These non-adiabatic events occur precisely at the field offsets predicted by theory. It is demonstrated that in the adiabatic regime the effects of field fluctuations are fully reversible, while the occurrence of non-adiabatic events leads to hysteresis. The adiabatic range of field offsets can be increased by modifying the refocusing pulses within the CPMG sequence.

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