arXiv:1104.3177 Optical pulse-shaping for internal cooling of molecules Chien-Yu Lien , Scott Williams, and Brian Odom Department of Physics and Astronomy, Northwestern University International Symposium on Molecular Spectroscopy 66th Meeting 2011.06.24
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ArXiv:1104.3177 Optical pulse-shaping for internal cooling of molecules Optical pulse-shaping for internal cooling of molecules Chien-Yu Lien, Scott Williams,
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arXiv:1104.3177
Optical pulse-shaping for internal cooling of molecules
Chien-Yu Lien, Scott Williams, and Brian Odom
Department of Physics and Astronomy, Northwestern University
International Symposium on Molecular Spectroscopy66th Meeting
2011.06.24
Applications:
• Molecular clock
• Test on fundamental constant
• Quantum computation
• Cold chemistry
.
.
Internal Cooling !?
-> Prepare molecules in desired low energy states
Methods:
• Buffer gas cooling
• Supersonic expansion
• Stark deceleration
• Optical pumping
.
.
What about rotational degree of freedom
M. Viteau et al, Science, 2008, 321, 232–234.
Achieve rotational cooling in 10s of seconds
P. F. Staanum et al., Nature Physics, 2010, 6, 271–274. T. Schneider et al., Nature Physics, 2010, 6, 275–278.
Apparatus – RF Paul trap
pulse valve
source chamber
exp. chamber
AlH+
r0 = 3 mmz0=15mmΩrf = 2MHz
Internal degrees of freedom are not cooled!
Ba+
v” = 0
v” = 2
v” = 1
v’ = 0
v’ = 1
1500 cm-1
300 K ~ 200 cm-1
Diagonal Frank-Condon factors of AlH+
AlH+
Rotational optical pumping in AlH+
K’ J’ 3 2.5
2 1.5
1 0.5
K” J”3
2
1
0
2.51.5
1.50.5
0.5
P−+
+−
−+
++
−−
+
−−
3.52.5
pumping decay
MirrorGrating
Mask
Mirror
Concave Mirror
Pulse shaping
Pillet’s group cooled the vibrational DOF with this technique
Better than the required 10 cm-1 for cooling AlH+
Data
PROC (Pulse-shaped Rotational Optical Cooling)
Rate Equation Simulation
1 + 1’ REMPD state readout
M. F. Guest and D. M. Hlrst, Chemical Physics Letters, 1981, 84, 167.P. J. Bruna and F. Grein, Physical Chemistry Chemical Physics, 2003, 5, 3140.
Conclusions
• This scheme cools internal DOF in 10μs compared to 10s of seconds
• Complementary to the work of Drewsen and Schiller’s groups