Graduate Program Events

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Events During the Week of September 3rd through September 10th, 2023

Monday, September 4th, 2023

Labor day
Abstract: *Note: actual end time may vary.* URL:
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Tuesday, September 5th, 2023

Graduate School Fall 2023: Fall degree window period deadline for doctoral students
Time: 11:55 pm - 12:55 am
Abstract: Degree candidates must complete all steps: *Important Note: The “Window Period” is the time between the end of one degree period and the beginning of the next. You must have been registered for the previous semester (Fall, Spring, or Summer). If all degree requirements are met by the end of the window period, your degree will be granted for the following semester. However, you will not have to register or pay fees for the next semester. CONTACT: 262-2433,
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Wednesday, September 6th, 2023

Fall semester instruction begins
Abstract: *Note: actual end time may vary.* URL:
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Thursday, September 7th, 2023

No events scheduled

Friday, September 8th, 2023

Advances in All-Optical Magnetometry for Femto-Tesla Sensitivity in Earth-Field-Scale Magnetic Fields
Time: 9:00 am - 10:30 am
Place: 5280 Chamberlin
Speaker: Michael Bulatowicz, Department of Physics Graduate Student
Abstract: The ability to detect femto-Tesla ($10^{-15}$) magnetic fluctuations in the presence of large background magnetic fields encountered in unshielded environments on Earth is a capability which can enable a wide array of applications presently requiring magnetically shielded environments. This has been possible for many years through the use of superconducting quantum interference devices (SQUIDs); however, SQUIDs are expensive to purchase, operate, and maintain. In contrast to SQUIDS, optically pumped magnetometers based on warm alkali vapor are relatively inexpensive to purchase, operate, and maintain while promising similar sensitivity capabilities.

In the present work, I have demonstrated an optically pumped scalar magnetometer using a 1 cm diameter by 1 cm length internal dimension cylindrical vapor cell with a photon shot noise limit of 3.5 $fT/\sqrt{Hz}$ and a demonstrated single-channel noise of 10 $fT/\sqrt{Hz}$ as limited by the electrical current source generating a 29 $\mu T$ bias field. I have further demonstrated a differential pair of these magnetometers, separated by a distance of 9 cm, with measured differential noise of 1 $fT cm^{-1}/\sqrt{Hz}$, consistent with a single-channel noise of 6 $fT/\sqrt{Hz}$. I present a straightforward procedure for optimization of the sensitivity of this magnetometer to achieve fundamental sensitivity limits in the low single digit $fT/\sqrt{Hz}$ and guidelines for detection electronics supporting total noise from the magnetometer dominated by the fundamental sensitivity limit. I demonstrate, analyze, and characterise the basis of a method for detection of the vector components of the incident magnetic field through the use of an applied oscillating field along each vector axis to be measured, and I present initial results with single-axis vector component detection. Included in the relevant chapter are algorithms and feedback methods for achieving high performance, along with a demonstration of each, and measurements of performance including relative accuracy and uncertainty. I further present a demonstration and theory of detection of RF magnetic fields near the natural Larmor precession frequency of the spins, taking advantage of the AC Stark shift of the optical pump beam to generate a linear sensitivity to the RF signal, measured at the difference between the RF frequency and Larmor frequency. Finally, I look toward future work, proposing a method for measurement of the vector direction of the incident magnetic field by real-time observation of the spin precession.
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