Date Thesis Awarded
Honors Thesis -- Open Access
Bachelors of Science (BS)
We demonstrate a method of measuring small constant gradients on top of a large constant background magnetic field using Electromagnetically Induced Transparency (EIT). The Earth provides a constant magnetic field of 25-50 μT, and as such, measuring much smaller magnetic fields as well as smaller gradients presents a challenge often requiring special shielding. We show that by making use of common mode noise subtraction from a dual rail setup, our measurement is insensitive to these large fields, and in theory our method does not require shielding. Our dual rail setup allows us to measure small magnetic field gradients by utilizing EIT resonances in 87Rb. In order to detect a cardio-magnetic field gradient, a magnetometer must be sensitive to gradients on the order of 10-100 pT. Our setup has been found to be sensitive to magnetic field gradients as low as 400 pT, and has the necessary bandwidth to acquire gradient fields at the rate necessary to detect features of the heart's magnetic field. We also discuss potential future work that could be done to remove the necessity of shielding and produce greater sensitivity.
Fay, Alexander, "Atomic Magnetometry for the Detection of Cardio-magnetic Fields" (2020). Undergraduate Honors Theses. William & Mary. Paper 1454.