1. Engineering and Control of Cold Molecules N. P. Bigelow University of Rochester

2. Why Cold (Polar) Molecules ?

3. Talks from: Shlyapnikov Pfau Burnett Sengstock.

4. Why Cold (Polar) Molecules ? Talks from: Shlyapnikov Pfau Burnett Sengstock. More Reasons Later in Talk

5. So what about cold molecules? Hard to find cycling transitions  Laser cooling of molecules is hard if not impossible

6. Doyle approach - Thermalization with cold helium gas & magnetic trapping Dilution Refrigerator ~mK Paramagnetic molecules Large samples

7. Meijer - time and spatially varying E fields – decelerator – (à la high-energy in reverse; H. Gould) accelerate

8. Meijer - decelerator (à la high-energy; H. Gould) decelerate

9. Here “Build” the molecules from a gas of pre-cooled atoms via photoassociation

10. A Quick Review of Photoassociation Starting with Homonuclears

11. Molecular potentials Ground state Singly excited state Homonuclear

12. Photoassociation Ground state Singly excited state photon 600-1000Å

13. Ground state molecule formation? Ground state Excited state photon Sp. emission

14. (transition rate)  (collision rate& pair distribution)* (excitation rate)* (survival rate)*(process probability)* (density 2 )*(volume) These factors determine molecular production rates

15. Ground state molecule formation photon Sp. emission  i   f  Poor Franck-Condon factors are discouraging  f  i   0

16. In 1997 Pierre Pillet and co-workers startled the community by showing the Cs 2 ground-state molecules were produced in a conventional optical trap

19. R-transfer method Frank-Condon Matching

22. Why not heteronuclear molecules?

23. Molecular potentials Ground state Singly excited state Far better Franck-Condon factors….

25. We might be CLOBBERED by the pair distribution function R homo /R hetero = 950/76 ~ 13 (R homo /R hetero = 950/76 ~ 1/10) 2 ~ 100 ! The interaction time is also smaller by a factor of ~ 13!

26. Nevertheless, several groups built multi- species MOTs - including Rochester and Sao Carlos and

27. Kasevich Arimondo Ingusio Weidemuller Windholz DeMille Stwalley/Gould Wang/Buell Ruff others Bose-Fermi&Isotopic: Jin, Salamon, Ertmer, Ketterle, Hulet, Sengstock… Sukenik NaCs NaK NaRb RbCs KRb LiCs LiNa ? Most “reactive”

28. We started with Na + Cs

29. Search for ground state molecules - the detection pathway 20-200  J 9ns 580-589 nm 2 mm 2

30. NaCs formation and detection Traps 100  J pulse @ 575-600nm time (  s) -30 0 20 10 5 9ns

31. Choice of pulsed laser wavelength 575-600 nm was chosen  To implement a resonant ionization pathway  It has enough energy to 2-photon ionize NaCs  It will NOT resonantly ionize Cs

32. Na+Cs Lin Scale Zoom photons cold Na Thermal Na Cold Cs Cold NaCs Cs 2 Na 2 Time of Flight

34. Is NaCs formed by the ionizing pulse ? Traps Ionizing Pulse time (  s) -30 -15 0 20 10 5 9ns Na-push beam

35. Push –beam experiment

36. How cold are the molecules? We use time-of-flight from the interaction zone as our probe

37. NaCs Temp T NaCs ~ 260  K 0.2 m/s (kinetic temp)

38. K NaCs : The rate of formation  We detect 500 molecules in 10,000 pulses  Estimate ionization and detection efficiency ~ 10%  Kinetic model : 90% of NaCs drifts out of the trapping region between pulses.  Production rate ~ 50 Hz  d [NaCs] / dt = K NaCs [Na][Cs]  K NaCs ~ 7.4 x 10 -15 cm 3 s -1

39. Measured depth of the triplet is 137-247 cm -1 Neumann & Pauly Phys. Rev. Lett. 20, 357-359 (1968). and J. Chem. Phys. 52, 2548-2555 (1970) We have scanned 0 – 268 cm -1 and found strong ion signals (includes 5% of singlet potential) We have a mixture of singlets and triplets C. Haimberger, J. Kleinert, npb PRA Rapid Comm. 70, 021402 (R) Aug 2004 NaCs has largest polarizability (measured) of all bi-alkalis

40. Coherent Transfer - State Selective Ro-vibrational ground state (lower dipole moment) or Single excited ro-vibrational state Incoherent transfer results already at Yale

41. The most important part of this part of our work: C. Haimberger J. Kleinert (M. Bhattacharya, J. Shaffer & W. Chalupczak)

42. KRb

43. RbCs

44. 40,000 molecules/sec !! KRb

45. Franck-Condon Factors for hetero-pairs based on long range (dispersion) potentials Wang & Stwalley, J. Chem Phys.

46. Cold (Polar) Molecules and Quantum Information

47. Polar Molecules Allow Coupling Enabling Quantum Information Applications Heteronuclear molecules are highly polarizable The dipole-dipole coupling of the molecules can be harnessed for quantum information applications (see protocols for EDMs in Quantum Dots - e.g. Barenco, et al PRL 82 1060)

48. Polar Molecules Allow Couplings Enabling Quantum Information Applications (based on scheme by Côté, Yellin [Lukin]) atoms bound molecular states

49. Polar Molecules Allow Coupling Enabling Quantum Information Applications atoms bound molecular states Start with two molecules in same state

50. Polar Molecules Allow Coupling Enabling Quantum Information Applications atoms bound molecular states Start with two molecules in same state Use Raman pulses - create superposition

51. Polar Molecules Allow Coupling Enabling Quantum Information Applications atoms bound molecular states Two-molecule state:

52. Polar Molecules Allow Coupling Enabling Quantum Information Applications (large dipole moment) Now excite  to the state 

53. Polar Molecules Allow Coupling Enabling Quantum Information Applications (large dipole moment) Now excite  to the state , wait an Interaction time  then de-excite back to  1  Phase gate, CNOT gates etc. possible “Dipole blockade and quantum information processing using mesoscopic Atomic ensembles”, Lukin, Fleischhauer, Côté, Duan, Jaksch, Cirac and Zoller PRL 87 037901

54. A specific qubit platform Each atom sees a local field that couples it to its neighbors and permits selective addressing The coupling cannot be switched off but instead can be compensated using echo-type refocussing techniques of NMR. What is needed is a source of cold molecules D. DeMille, PRL 88, 067901

55. Molecules and “Chips”

56. Atom Chip Si(1mm) SiO 2 (250nm) Ag(50nm) Cu(1mm)  + -  - polarization I B ~15-20 A I S ~1-3 A Y Z x B=B 0 y z0z0 z y

57. Our 1 st Generation Atom Chips 20 mm 5 mm 2 mm 1 mm 10 mm y x w=250  m h=1-5  m J~ 10 6 A/cm2 Cross-section: Current density:

58. Trap Image of Trap Atom chip surface Cold Atomic Mixtures-on-a-chip Rb-Cs Holmes, Tscherneck, Quinto-su and Bigelow Imaging of sample

59. 2 nd Generation Chips P. Quinto-Su, M. Tschernek, M. Holmes and N. P. Bigelow, On-chip detection of laser-cooled atoms, Optics Express, 12, 5098 (2004). Collaboration with Corning, Inc. <100 atom sensitivity

60. 3 rd Generation Chips: Molecule Chips

61. WHY OPTICS and MOLECULES ON THE CHIP?

62. Optical Fiber Probe/readout/control laser WHY OPTICS and MOLECULES ON THE CHIP?

63. 4 th Generation Chips 3 cm Higher current Capability

64. Heroines and Heroes of this part of the work: Michaela Tscherneck Michael Holmes Pedro Quinto-Su C. Haimberger J. Kleinert

65. Vortex Lattice in a Coupled Atom-Molecule Condensate (non-polar molecules)

66. Single component atomic BEC - Triangular vortex lattice Ω is rotation frequency

67. Mean-field model Three scattering constants g a, g m and g am Coherent constant  Two Gross-Pitaevskii equations Atom-Molecule BEC (homo-nuclear)

68. Atom-Molecule BEC – Energies –Two key types of interaction between atoms and molecules Coherent coupling Interspecies scattering

69. Atom-Molecule BEC - rotating (n v ) m = 2(n v ) a Vortex density of molecular condensate is twice that of the atomic condensate

70. Vortex Lattice in a Coupled Atom-Molecule Condensate (non-polar molecules) Sungjong Woo Department of Physics & Astronomy University of Rochester Q-Han Park Department of Physics Korea University

71. Summary We can create cold diatomic polar molecules We can create them and manipulate them on “chips” There are interesting new aspects of degenerate systems involving molecules

72. Summary We can create cold diatomic polar molecules We can create them and manipulate them on “chips” There are interesting new aspects of degenerate systems involving molecules Can you calculate your Archimedes factor?