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Observation of an Efimov spectrum in an atomic system

Observation of an Efimov spectrum in an atomic system. Accademia dei Lincei, Roma, October-20-2009. Matteo Zaccanti LENS, University of Florence. Universality in 3-(4)-body systems. Efimov effect. ?. | a | ∞. | a |.  r 0. See B&H review 2006. Universality in 3-(4)-body systems.

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Observation of an Efimov spectrum in an atomic system

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  1. Observation of an Efimov spectrum in an atomic system Accademia dei Lincei, Roma, October-20-2009 Matteo Zaccanti LENS, University of Florence

  2. Universality in 3-(4)-body systems Efimov effect ? |a|∞ |a| r0 See B&H review 2006

  3. Universality in 3-(4)-body systems No additional 4-body parameter Each Efimov state accompanied by two 4B states Hammer et al, Eur. Phys. J. A 32, 113 (2007) von Stecher et al, Nat.Phys. 5, 417 (2009)

  4. To summarize… Ultracold atomic gases + Feshbach resonances Ideal test bed for Efimov physics!!! To explore Efimov scenario: • Tunable a over wide range • Low collision energy Kraemer et al., Nature 440, 315 (2006) Ottenstein et al., PRL 101, 203202 (2008) Knoop et al., Nat. Phys. 5, 227 (2009) Ferlaino et al. PRL 102, 140401 (2009) Barontini et al., PRL 103, 043201 (2009)Williams et al., PRL 103, 130404 (2009) Gross et al., PRL 103, 163202 (2009)

  5. To take in mind… Efimov scenario r0 =0 Real world r0 ~lVdW Coincidence only as |a|>>r0 Expected deviations for the deepest states of the ladder Additional 3-body parameter is needed!!! (Unknown location of the first Efimov feature)

  6. Efimov scenario & 3-body observables Universal relations between a-n a+n and a*n

  7. Efimov physics in 39K • Small abg (-29 a0) & Broad FRs (50-70 G) D’Errico et al. NJP 9, 223 (2007)

  8. Efimov physics in 39K • Good control on a (B), especially at small a Roati et al., Nature 453, 896 (2008) Roati et al, PRL 99, 010403 (2007) Fattori et al, PRL 100, 080405(2008) Fattori et al, PRL 101, 190405 (2008)

  9. Efimov physics in 39K Just few remarks about our system: • lvdw=64 a0 • r0=29(x2) a0 • our feature is not so broad: (See Chin et al. arXiv:0812.1496)

  10. Efimov physics in 39K 3-body recombination vs a Explored: [-300; -8000] a0 [+20;+25000] a0

  11. Efimov physics in 39K Presence of two trimer states very close to Efimov scenario!!! M. Z., B. Deissler, C. D'Errico, M. Fattori, M. Jona-Lasinio, S. Müller, G. Roati, M. Inguscio & G. Modugno, Nature Physics, 5, 586 (2009)

  12. Efimov physics in 39K: a>0 side a > 0 Two recombination minima

  13. Efimov physics in 39K: a<0 side … and associated 4-body feature(s) a < 0 One Efimov resonance…

  14. Efimov physics in 39K: AD resonances … close to the AD resonances (unexpected) a > 0 Two recombination maxima…

  15. Efimov physics in 39K: AD resonances Usually, the three-body process causes nl =3 K3=3a

  16. Efimov physics in 39K: AD resonances Similar in BEC of 87Rb above critical opacity …but if AD cross section is large it can be nl >>3!!!

  17. Efimov physics in 39K: AD resonances Note that inelastic AD scattering causes an increase of only nl =3->nl =4

  18. Efimov physics in 39K: AD resonances Idea confirmed by a simple model of AD collisions: pe= prob. for D of elastic AD collision before leaving the trap Simple considerations allow to estimate them: pi(k)= prob. for D of inelastic AD collision before the k-th el. coll After kM ED<ETrap kS such that pi(kS)=1

  19. Efimov physics in 39K: AD resonances • D can do many different paths before escaping the trap: • k el. Coll. + 0 in. • k el. Coll. +1 in. • k>kM el. Coll. (ED<ETrap) +1 in. if kM<kS • k=kS el. Coll. +1 in. (for sure) if kM>kS Include all possible multiple scattering events and extract nl : Then, compare exp. data with

  20. Efimov physics in 39K: AD resonances Zero energy AD scattering overestimates the effect: reasonable, since we are not at E=0

  21. Efimov physics in 39K: AD resonances Similar mechanism at the other feature

  22. Ideal vs real world: a comparison Larger spacing Simultaneous fit gives: s0=0.956(18)

  23. Ideal vs real world: a comparison Consistent with recent theo. predictions Hammer et al., PRA 75 032715 (2007) Thøgersten et al., PRA 78 020501 (2008) Platter et al., PRA 79 022702 (2009) D’incao et al., J. Phys. B 42 044016 (2009)

  24. Ideal vs real world: a comparison Comparison with Massignan & Stoof PRA78, 030701(R) (2008) Despite accidental agreement… Thank you for motivating our work!!!

  25. Outlook & Conclusions • Different FRs: other Efimov spectra on the same atomic system. • Further investigations: AD scattering, 4-body features, association of Efimov trimers… • Universality vs short-range effects

  26. Thank you for your attention!

  27. Efimov scenario & 3-body observables 3-body recombination particle-dimer scattering

  28. Efimov scenario & 3-body observables

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