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

• Advantage of choosing AlH+ :

• Diagonal FCFs

• Simple pulse-shaping

• Extension to other molecules:

• A second fs laser to repump v” > 0 population

Current Progress

• Pulse-shaped laser ready

• AlH sample generation ready

• Ion trap ready

• Vacuum system ready

• Next: start trapping!

More info.-- arXiv:1104.3177

Acknowledgement

Thanks to:

• Prof. Brian Odom

• Scott Williams – laser spectrum

• Dr. Jason Nguyen – simulation

• Chris Seck

• And your attention!!

Addition slides in the back

http://www.zazzle.com/geeksgetit