1. Millimeter Wave Spectroscopy of Rydberg States of Molecules in the Region of 260-295 GHz David Grimes, Yan Zhou, Timothy Barnum, Robert Field Department of Chemistry, MIT 1

2. Outline Brief discussion of the importance of Rydberg states of molecules Review of previous FID detected millimeter wave spectroscopy of Rydberg states of molecules Difficulties with previous experimental setup Overview of the 260-295 GHz CPmmW spectrometer and experimental set up Some representative results and preliminary quantitative Stark demolition data 2

3. Uses of Rydberg states of molecules 3 State selective ion generation Molecular deceleration Molecular Ion Structure Quantum Information Hudson, Odom Lundeen (atoms), Field Merkt, Meijer, Lewandowski,,Ubachs, Hinds Field, Cornell

4. Previous Work 4 detector generator n = 30 – 60 6s 2 1 S 0 6snp 1 P 1 75 – 98 GHz 1 S 0 or 1 D 2 ~42000 cm -1 Ba I.P ≈ 42000 cm -1 C2ΠC2Π X2Σ+X2Σ+ ~20100 cm -1 ~18600 cm -1 n~43, l =3 n-1, l +1 n+1, l +1 BaF I.P ≈ 39000 cm -1 D 0 ≈ 48200 cm -1 75 – 98 GHz

5. Superradiance in Barium 5 75kHz 150kHz

6. Laser Millimeter Wave Spectrum of Barium Fluoride 6 ? 18455184601846518470184751848018485 Laser Wavelength (cm -1 )

7. Previous work on Stark Demolition 7 CNP CP ~10MHz Time State preparation Chirped Pulse Free Induction Decay Electric Field CP 1V/cm FID CP FID CP 1V/cm FID CNP No FID!

8. Drawbacks of the Previous Setup 8 detector generator Large Density Gradient Stark plates have incomplete coverage Magnetic Field Gradient Mesh collects barium

9. New experimental setup 9 detector generator

10. Non-reproducible Spectra 10

11. Revised millimeter wave setup 11 10MHz Rb Osc 8.8 GHz PDRO Agilent AWG 12Gs/s x24 Tektronix Scope 50 GS/s, 20 GHz Variable Attenuator Molecular beam x12    DC Block Sub-harmonic Mixer 2.0 – 3.5 GHz Chirp Single Frequency LO 260-295 GHz 30 mW max power

12. Demonstration of the new setup 12 Ba 30p -> 28d 10000 averages, 30 minutes 300 kHz lowest observed linewidth 30p 28d

13. Easy assignment of sequential excitations 13 Ba 39p -> 36d 1000 averages Ba 36d -> 35f 1000 averages 39p 36d 35f

14. Quantitative work on Stark Demolition 14

15. The effect of magnetic fields on Stark Demolition 15

16. Summary Transitioned to a transverse excitation scheme for performing Rydberg-Rydberg FID detected millimeter wave spectroscopy Demonstrated the use of 260-295 GHz millimeter waves for probing Rydberg-Rydberg transitions Began probing the effects of Stark demolition in a systematic, quantitative manner In future, will revisit molecular experiments with a deeper understanding of level structure and Stark demolition, and superradiance with a more controlled density of emitters. 16

17. Acknowledgements 17 Prof. Robert Field Dr. Yan Zhou Tim Barnum Dr. Steve Coy Ethan Klein Dr. Tony Colombo Dr. Jeff Kay Dr. Carrie Womack Dr. Barratt Park Jun Jiang Dr. Josh Baraban Bryan Changala Prof. John Doyle Dr. Dave Patterson Prof. Dave DeMille Dr. John Berry Prof. Brooks Pate Dr. Nathan Seifert Prof. John Muenter