The narrow $s$-wave Feshbach resonance of a ${}^6\mathrm{Li}$ Fermi gas shows strong three-body loss, which is proposed to be used to measure the minute change of a magnetic field around the resonance. However, the eddy effect will cause ultracold atom experiencing a magnetic field delay to the desired magnetic field from the current of the magnetic coils. The elimination of the eddy effect will play a key role in any experiments that are motivated to measure the magnetic field to the precision of a parts per million stability. Here, we apply a method to correct the eddy effect for precision measurement of the magnetic field. We first record the three-body loss influenced by the induced eddy effect, then we use a first-order decay model to obtain the time constant of the actual magnetic field by fitting the atom loss. This precisely determines the actual magnetic field according to the time response of the three-body loss. After that, we implement the desired magnetic field to the atoms so that we can analyze the three-body loss across the narrow Feshbach resonance. The measured magnetic-field-dependent rate of three-body loss at an ultralow temperature shows that the three-body recombination is the dominated loss mechanism near the resonance. We expect this practical method of correcting the eddy effect error of the magnetic field can be further applied to future studies of quantum few- and many-body physics near a narrow Feshbach resonance.

中文翻译：

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通过窄 Feshbach 共振附近的三体损耗表征磁场

狭窄的 $秒$波 Feshbach 共振 a ${}^6李$费米气体显示出很强的三体损耗，建议将其用于测量共振周围磁场的微小变化。然而，涡流效应会导致超冷原子经历磁场延迟，从磁线圈的电流到所需的磁场。消除涡流效应将在任何旨在以百万分之几的稳定性精度测量磁场的实验中发挥关键作用。在这里，我们应用一种方法来校正涡流效应以精确测量磁场。我们首先记录了受感应涡流效应影响的三体损耗，然后我们使用一阶衰减模型通过拟合原子损耗来获得实际磁场的时间常数。这根据三体损耗的时间响应精确确定了实际磁场。之后，我们对原子实施所需的磁场，以便我们可以分析狭窄的 Feshbach 共振中的三体损失。在超低温下测量的三体损耗的磁场相关率表明，三体复合是共振附近的主要损耗机制。我们期望这种校正磁场涡流效应误差的实用方法可以进一步应用于未来对窄 Feshbach 共振附近的量子少体和多体物理学的研究。在超低温下测量的三体损耗的磁场相关率表明，三体复合是共振附近的主要损耗机制。我们期望这种校正磁场涡流效应误差的实用方法可以进一步应用于未来对窄 Feshbach 共振附近的量子少体和多体物理学的研究。在超低温下测量的三体损耗的磁场相关率表明，三体复合是共振附近的主要损耗机制。我们期望这种校正磁场涡流效应误差的实用方法可以进一步应用于未来对窄 Feshbach 共振附近的量子少体和多体物理学的研究。