1. Optical Pumping I’M SO PUMPED FOR THIS!!! I also am quite excited By
David Ray

2. 1
Introduction
What am I presenting?

3. Historical Background
Discovered By Alfred Kastler
Led to the development of lasers
Awarded Nobel Prize in 1966

4. Caesium: 1s22s22p63s23p63d104s24p64d105s25p66s1
Angular Momentum
Caesium: 1s22s22p63s23p63d104s24p64d105s25p66s1
[Xe]6s1
F=5
F=4
F=3
(I=7/2)
6s1/2
6p3/2
6p1/2 6s 6p L S J I F
Fine structure
Hyperfine structure

5. Zeeman Effect Hyperfine structure mF =-F,-F+1,…,F Zeeman mF=1 mF F ΔEF
ΔEF = gF µB |B| mF
(gF=1/4)

6. Pumping
Right circularly polarised light imposes absorption selection rule mF=+1
Spontaneous emission selection rule mF=-1,0,1
F=1
p1/2
No available transiton
i.e. atom’s “Pumped” -1 mF 1
F=1
s1/2
Zeeman

7. Transitions Spontaneous Emission Stimulated Emission ΔE
Photon approaches electron
Electron’s in excited state
Photon’s absorbed
Photon matching ΔE approaches electron
Spontaneous emission
Stimulated emission
Photon approaches
Excited state
Ground state
Excited state
Electron emits photon in random direction
Stimulates emission of photon

8. Rabi Oscillations
Population is the percentage of electrons in a given state
Rabi oscillations are the fluctuations of the population with respect to time
Stimulated emission
Absorption
Stimulated emission
System is “Pumped”
Stimulated emission
Stimulated emission
P(ground) ∝ sin2( ωt/2)
P(ground) + P(excited) = 1

9. 2
Methodology
How will this be achieved?

10. (temperature controlled)
Equipment
Focusing lens
RF coil
Linear polariser
Focusing lens
Light rack
Caesium Chamber
Photo-detector
Quarter-wave plate
Interference filter
Caesium lamp
(temperature controlled)
Horizontal field
& Sweep field

11. Earth’s Magnetic Field
Photorack provides a channel to oscilloscope based on opacity of Caesium Chamber
Photorack
Oscilloscope
Sweeping field & Horizontal Field
RF field
This is dependant on this equation
ΔEF = gF µB |B| mF
When B is such a value that
hf = gF µB |B| mF
Opacity will drop
|B| = √(BC+BE||)2 +BE ⊥ 2

12. Rabi oscillations RF field is periodically turned off Pulse Generator
Photorack
Oscilloscope
Horizontal Field
RF field
Pulse Generator
Plot a curve to fit resulting oscillations

13. 3
Results
What was observed?

14. Earth’s Magnetic Field
B/T
fres
/Hz
Plotted fres vs. B
By:
hf = gF µB √(BC+BE||)2 +BE⊥2 mF
A occurs when
BE|| =-BC
Graphs linear when
BE ~0
∴BE = 50.3± 2.3 µT

15. Rabi Oscillations ω = 4736 ± 5 Hz Fitted e-at+sin(ωt)+c
ω corresponds to Rabi frequency
ω = 4736 ± 5 Hz

16. 4
Conclusion
What does this all mean?