An atomic Fermi gas near a p-wave Feshbach resonance

1. An atomic Fermi gas near a p-wave Feshbach resonance D. Jin JILA, NIST and the University of Colorado $ NSF, NIST

2. Outline • Motivation • A p-wave Feshbach resonance • Molecule energies and lifetimes • Future

3. Fermionic superfluidity Cooper pairing: two correlated fermions act like a boson Examples Fermi condensate Superconductivity: Cooper pairs of electrons Superfluid 3He: 3He atom pairs Superfluidity in nuclear matter:Nucleon pairs

4. P-wave pairing? • Fermi condensates with non-s-wave pairing? • Examples: • superfluid 3He (p-wave) • high Tc superconductors (d-wave) • Novel features: • anistropic gap • multiple superfluid phases, • narrow resonance s-wave L=0 p-wave L=1 m l= -1,0,+1

5. Making molecules • This is the first step toward making molecule condensates andfermion pair condensates. • New possibilities: non-s-wave molecules, heteronuclear molecules, fermionic molecules, ground-state molecules, and polar molecules. • other non-s-wave Feshbach molecule studies: • Grimm (s- to g- wave), Salomon (p-wave)

6. Making molecules • Molecules can be very efficiently created using a Feshbach resonance. • magnetic-field sweep across resonance • three-body collisions near a Feshbach resonance • rf association • magnetic-field modulation

7. Feshbach resonance A magnetic-field tunable atomic scattering resonance Channels are coupled by the hyperfine interaction. molecule state in channel 2 → ← colliding atoms in channel 1

8. V(R) centrifugal barrier 0 V(R) R 0 R P-wave resonance S 300 mK 0.5 mK 300 K

9. Collisions and Fermions two spin-states 40K elastic collision cross section one spin-state B. DeMarco et al., PRL 82, 4208 (1999)

10. P-wave resonance 40K elastic collision cross section spin-polarized gas |f=9/2, mf=-7/2> C.A. Regal, C. Ticknor, J.L. Bohn, & D.S. Jin, PRL 90, 053201 (2003)

11. ml = ±1 ml = 0 B0 = 198.8 G B0 = 198.3 G Multiplet structure B ml = 0 ml = ±1 C. Ticknor, C.A. Regal, D.S. Jin, and J.L. Bohn, PRA 69, 042712 (2004).

12. Width of loss feature ml = 0 resonance Feature of a narrow resonance

13. centrifugal barrier V(R) 0 R B below both resonances B-field modulation Near a Feshbach resonance, a resonant oscillating B-field can create molecules. dissociation M. Greiner, C.A. Regal, & D.S. Jin, PRL 94, 070403 (2005) association S.T. Thompson, E. Hodby, & C.E. Wieman, PRL 94, 190404 (2005)

14. Quasi-bound molecules V(R) centrifugal barrier 0 R B above the resonance

15. P-wave molecule energy B ml = ±1 ml = 0 J.P. Gaebler, J.T. Stewart, J.L. Bohn, & D.S. Jin, PRL 98, 200403 (2007)

16. A way to “see” molecules Create molecules V(R) 0 R Look for energetic atoms created by tunneling

17. A way to “see” molecules B ml = ±1 ml = 0

18. A way to “see” molecules B ml = ±1 ml = 0

19. Molecule lifetime molecule creation B resonance time hold time ml = ±1 t =1.2 ms

20. Quasi-bound molecule lifetime molecule creation B resonance time hold time

21. Molecule Lifetimes ml = 0 ml = ±1 J.P. Gaebler, J.T. Stewart, J.L. Bohn, & D.S. Jin, PRL 98, 200403 (2007)

22. Dipolar relaxation Since our atoms are not in the lowest energy spin state, the molecules can undergo “one-body” decay. bound free This decay process would not exist for atoms in the lowest energy spin state. (6Li has such a p-wave resonance).

23. Collisional decay After removing atoms (blasting with resonant light) t = 7 ± 1 ms ml = 0

24. What’s next? ml = 0 ml = ±1

25. Molecule Creation B resonance time ml = ±1 ml = 0

26. Molecule Creation

27. Molecule Creation

28. V(R) 0 R Conclusion: • We can create and detect p-wave Feshbach molecules in a Fermi gas of atoms. • Novel aspects include: • Centrifugal barrier • Quasi-bound state • Narrow resonance • The molecule lifetime is short.

29. Group Members J. Goldwin P-wave molecule work: Jayson Stewart, John Gaebler M. Olsen