1. Jerzy Zachorowski M. Smoluchowski Institute of Physics, Jagiellonian University Nonlinear Spectroscopy of Cold Atoms, Preparations for the BEC Experiments

2. The Group Tomasz Brzozowski Maria Mączyńska Jerzy Zachorowski Michał Zawada Wojciech Gawlik IF UJ

3. Magneto-Optical Trap I I 85 Rb N  10 8 T  100  K

4. Spectroscopy of Cold Atoms -40-20020 -50 -40 -30 -20 -10 0 20 I = 22.4 · I 0 Detuning from the 3-4 resonance [MHz] trap - probe [MHz] -2012 -202 1

5. Laser system

6. Central Structure Raman transitions between light-shifted Zeeman sublevels Raman transitions between vibrational levels in the optical lattice

7. Zeeman sublevels

8. Vibrational levels Electric field in the trap: 6 beams of different polarizations. Relative phases not fixed, but relatively stable. Interference: intensity and/or polarization modulation. Additional optical forces (dipole forces). Atoms cooled and localized in the lattice nodes. Atomic movement quantized: vibrational energy levels.

9. Remarks New experiments: trap modulation Difference absorption-wave mixing Ultra-narrow central resonance

10. Bose-Einstein Condensation de Broglie wavelength: density n, distance n 1/3, condensation when: Ketterle, PRL 77, 416 (1996)

11. Lower temperatures Spontaneous emission: temperatures limited to 10 – 1  K „Dark traps”: optical dipole or magnetic forces Cooling by evaporation 100 nK 100  K 300 K MOT MT

12. Three steps to BEC Magneto-Optical Trap: 1. Magneto-Optical Trap: temperature 10 mK, density 10 10 cm -3 limit – interaction with light. Magnetic Trap: 2. Magnetic Trap: trap in field minimum - only „low-field-seeking” states losses at B = 0. Evaporation cooling: 3. Evaporation cooling: forced evaporation of hot atoms, thermalisation by collisions.

13. 400 nK 200 nK 50 nK 1995 - E. Cornell & C. Wieman Rb 87 Evidence: narrow peak in velocity distribution peak’s amplitude  when T  cloud shape same as that of the potential well

14. Over 30 laboratories produce BEC 87 Rb, 23 Na, 7 Li, ↑H, He*,... Experiments with BEC Matter-wave optics: condensate interference, atom laser Nonlinear atom optics Superfluidity, vortices Ultra-low density condensed-matter: Mott insulator  Cold fermionsNow

15. Matter-wave Optics – Atom Optics coherent waves  interference MIT  ”atom laser” MPQ NIST

16. Nonlinear atom-optics  k in =  k out   in =   out a)light waves (material medium nonlinearity) b) matter waves (always nonlinear)BEC 1999 NIST (W. Phillips) & Marek Trippenbach (UW)

17. Superfluidity, Vortices MIT LENS, Florence

18. Ultra-low density condensed-matter Mott transition MPQ – Garching

19. 6000 87 Rb atoms loading time 8 s cooling time 2,1 s current 2A Micro-BEC Garching

20. Micro-BEC 2 Tubingen 87 Rb Number of atoms in BEC: 10 6 Condensation at T=1  K Cooling time 27s

21. Cold fermions Do not thermalize (Pauli exclusion) Sympathetic cooling e.g. fermion 40 K & boson 87 Rb, fermion 6 Li & boson 7 Li 2001 R. Hulet (Rice) Li 7 Li 6 1999 D. Jin (JILA) 40 K

22. Our way towards BEC MOT MT Magneto-optical trapping Magneto-optical trapping T  30  K, N  10 8 Transfer to magnetic trap by radiation pressure, recapture in a MOT recapture in a MOT separated vacuum regions differential pumping (10 -8 mbar  10 -11 mbar) Magnetic trapping: Magnetic trapping: forced evaporation of hottest atoms, thermalization by collisions T  100 nK, N  10 5 - 10 6 Element 87 Rb

23. Transfer of atoms repetitive pushing by resonant light beam, recapture in lower MOT collection speed: 10 8 –10 10 s -1 loading of lower MOT: 10 7 –10 9 s -1 constant pushing by narrow light beam (Dalibard) flux: ~10 8 s -1 magnetic transfer directly into magnetic trap (Hänsch ) 30% efficiency, complicated.

24. Magnetic traps QUIC = Quadrupole + Joffe configuration: B ≠ 0 at trap center DalibardHänsch

25. September 2002 Laser system prepared Upper MOT ready & operating Next steps: transfer & recapture magnetic trapping