CQuIC Seminars
Atomic Physics for Broadband, Small Active Volume Atomic Magnetometer
Presented by Yuan-Yu Jau, Sandia National Labs
In the past decade, the magnetic field sensitivity of atomic magnetometers (AMs) has been greatly improved. Different methods of operating AMs have been investigated. Comparing with the magnetic field sensitivity (a few fT/root(Hz) ) of a superconducting quantum interference device (SQUID), an optimized AM with a much better sensitivity at 0.16 fT/root(Hz) was demonstrated from gradiometry. AM is therefore considered as a more powerful and more convenient magnetic sensor. At Sandia, we are conducting an AM project with a final goal of constructing a magnetoencephalography (MEG) system using AM sensor array. This application requires good B-field sensitivity (≤ 10 fT/root(Hz) ), high signal bandwidth (≥ 100 Hz), and small active volume (< 0.1 cc). Establishing atomic physics model for such system is therefore very helpful to the system design, because most AM studies are pursuing ultra sensitivity with narrow bandwidth (a few Hz). In this talk, I will give a quick overview of our AM MEG project. I will review the method of eliminating spin-exchange decoherence to help improving the fundamental AM sensitivity. I will talk about the density-matrix modeling for an atomic vapor cell system and how the buffer gas filled in the vapor cell can significantly affect the AM performance. So far the published literature regarding atomic magnetometry have only discussed the effects of buffer gases to the ground-state spin relaxation mechanisms. I will show that the collisions between the excited alkali-metal atoms and buffer-gas atoms, which have been long ignored, have important impact to the AM performance. The results of theoretical modeling show good agreement with experimental data. Finally, I will present the best result from our experimental setup, which shows several fT/root(Hz) sensitivity and greater than 100 Hz measurement bandwidth from a 0.025 cc active volume.
3:30 pm, Thursday, February 6, 2014
PAIS-2540, PAIS
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