BEGIN:VCALENDAR
VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
BEGIN:VEVENT
SEQUENCE:0
UID:UW-Physics-Event-8384
DTSTART:20230908T140000Z
DTEND:20230908T153000Z
DTSTAMP:20260414T031201Z
LAST-MODIFIED:20230815T173905Z
LOCATION:5280 Chamberlin
SUMMARY:Advances in All-Optical Magnetometry for Femto-Tesla Sensitivi
 ty in Earth-Field-Scale Magnetic Fields\, Graduate Program Event\, Mic
 hael Bulatowicz\, Department of Physics Graduate Student
DESCRIPTION:The ability to detect femto-Tesla ($10^{-15}$) magnetic fl
 uctuations in the presence of large background magnetic fields encount
 ered in unshielded environments on Earth is a capability which can ena
 ble a wide array of applications presently requiring magnetically shie
 lded environments. This has been possible for many years through the u
 se of superconducting quantum interference devices (SQUIDs)\; however\
 , SQUIDs are expensive to purchase\, operate\, and maintain. In contra
 st to SQUIDS\, optically pumped magnetometers based on warm alkali vap
 or are relatively inexpensive to purchase\, operate\, and maintain whi
 le promising similar sensitivity capabilities.<br>\n<br>\nIn the prese
 nt work\, I have demonstrated an optically pumped scalar magnetometer 
 using a 1 cm diameter by 1 cm length internal dimension cylindrical va
 por cell with a photon shot noise limit of 3.5 $fT/\\sqrt{Hz}$ and a d
 emonstrated single-channel noise of 10 $fT/\\sqrt{Hz}$ as limited by t
 he electrical current source generating a 29 $\\mu T$ bias field. I ha
 ve further demonstrated a differential pair of these magnetometers\, s
 eparated 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 optimizati
 on of the sensitivity of this magnetometer to achieve fundamental sens
 itivity 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\, analy
 ze\, and characterise the basis of a method for detection of the vecto
 r components of the incident magnetic field through the use of an appl
 ied oscillating field along each vector axis to be measured\, and I pr
 esent initial results with single-axis vector component detection. Inc
 luded 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 uncertaint
 y. I further present a demonstration and theory of detection of RF mag
 netic 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 diffe
 rence 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 t
 he spin precession.
URL:https://www.physics.wisc.edu/events/?id=8384
END:VEVENT
END:VCALENDAR