1. Interference of Two Molecular Bose-Einstein Condensates Christoph Kohstall Innsbruck FerMix, June 2009

2. Johannes Hecker Denschlag Christoph Kohstall Stefan Riedl Rudi Grimm Edmundo Sánchez Guajardo Leonid Sidorenkov Fer(Mix)-Team

3. Interference of atomic Bose condensates A powerful tool to study Bose gases Interference meets Fermi gases Interesting challenges Interference of two independent BECs Andrews et al., Science 275, 637 (1997) Interference of atom lasers  coherence length Bloch et al., Nature 403, 166 (2000) Vortex in BEC  phase jump Inouye et al., Phys. Rev. Lett. 87, 080402 (2001) 2D  BKT transition P. Krüger et al., Phys. Rev. Lett. 99, 040402 (2007) 1D  Luttinger liquid Hofferberth et al., Nature Physics 4,489 (2008) Molecular BECs towards strong interaction Analysing different system sizes, we observe the crossover from thermal to quantum noise, reflected in a characteristic change in the distribution functions from poissonian to Gumbel type, in excellent agreement with theoretical predictions on the basis of the Luttinger-liquid formalism. We present the first experimental observation of quasi-long-range order in one-dimensional atomic condensates, Interference of two independent BECs Andrews et al., Science 275, 637 (1997) Fermions form bosonic pairs strong interaction Interference of two independent BECs Andrews et al., Science 275, 637 (1997)

4. Interference of atomic Bose condensates… a powerful tool to study Bose gases Now interference meets Fermi gases highlights and interesting challenges Interference of two independent BECs Andrews et al., Science 275, 637 (1997) Vortex in BEC  phase jump Molecular BECs towards strong interaction Analysing different system sizes, we observe the crossover from thermal to quantum noise, reflected in a characteristic change in the distribution functions from poissonian to Gumbel type, in excellent agreement with theoretical predictions on the basis of the Luttinger-liquid formalism. We present the first experimental observation of quasi-long-range order in one-dimensional atomic condensates, Interference of two independent BECs Andrews et al., Science 275, 637 (1997) Interference of atom lasers  coherence length Bloch et al., Nature 403, 166 (2000) Vortex in BEC  phase jump Inouye et al., Phys. Rev. Lett. 87, 080402 (2001) 2D  BKT transition P. Krüger et al., Phys. Rev. Lett. 99, 040402 (2007) 1D  Luttinger liquid Hofferberth et al., Nature Physics 4,489 (2008) bosonic pairs of fermions strong interaction from atoms to molecules

5. Fermionic lithium – our workhorse BECBCS moleculesmany-body pairs Let‘s open the door!

6. TOF-Images TOF=0.4 ms 4 ms 8 ms 12 ms 14 ms B = 700 G visibility ~25% z x 0 80 pixel 250 µm visibility fringe spacing phase z

7. Procedure x z y confinement z x z y x create split overlap observesplit create overlap observe AOM CCD lens trapping beam coils for mag. Feshbach field Li beam waist 54 µm ω y 2π*20Hz ω x, ω z 2π*150Hz mag. field 700 G N ↑,↓ 200 000 1/k F a3 separation64 µm

8. AOM CCD lens trapping beam coils for mag. Feshbach field Li 4 ms beam waist 54 µm ω y 2π*20Hz ω x, ω z 2π*150Hz mag. field 700 G N ↑,↓ 200 000 1/k F a3 separation64 µm in situ TOF=0 ms in expansion TOF = 14 ms Expansion clouds no slicing necessary magnifying glass trap position trap position trap position trap position

9. Relative phase phase potentialclouds Same result for independent BECs

10. ~0.5T F =T C TCTC Temperature dependence bars are rms

11. Interaction strength

14. interactions limitshort lifetime of moleculesno pairs in expansion We gotta be creative ! lifetimecollisions pairing 1/k F a (in situ) 410 detection efficiency depletion of BEC # of collisions mean field potential pair breaking many-body pairs detection 7% 17% 34% not valid E kin <E mf partial reflection E kin >E pairing mag. field 650700780834 no survival 0.1 1 30 a/a 0 50010003000  potential Depleted part has no common phase

16. interactions limitshort lifetime of moleculesno pairs in expansion We gotta be creative ! lifetimecollisions pairing 1/k F a (in situ) 410 detection efficiency depletion of BEC # of collisions mean field potential pair breaking many-body pairs detection 7% 17% 34% not valid E kin <E mf partial reflection E kin >E pairing mag. field 650700780834 no survival potential 0.1 1 30 a/a 0 50010003000 

17. Interference of molecular BECs The challenge of strong interaction Tool for new physics