Degenerate Quantum Gases on Atom Chips: Outlook and Interferometry

1. Degenerate Quantum Gasesmanipulation on AtomChips Francesco Saverio Cataliotti

2. Outlook • Bose-Einsteincondensates on a microchip • AtomInterferometry • MultipathInterferometry on anAtomChip • Results and Conclusions

3. Temperatura Fermioni Bosoni T < TF T < TC EF Degenerate atoms

4. Degenerate Atoms 1925: Einstein predicts “condensation” of bosons 60’s: Development of Lasers 80’s: Development of laser cooling 1985: Magnetic Trapping of ultracold atoms 1986: Optical trapping of Na 1987: Na Magneto-Optical Trap 1995: First 87Rb Bose-Einstein Condensate • Huge playground for fundamental physics: • BEC with Li, Na, K, Cs, Fr… • Optical gratings, collective excitations… • First applications: • Interferometry • Earth and Space sensors • Quantum Information 2001: First BEC of 87Rb on an Atom Chip

5.   10-20 T  300 K laser cooling   10-6 T  10 K evaporative cooling   2.6 T 100 nK Routeto BEC in dilutegases

6. MagnetoOptical Trap (MOT) trapping cooling

7. Forced evaporation in a magnetic trap (conservative potential) temperature Evaporative cooling remove highest velocities thermalization through elastic collisions cooling

8. BEC on a chip I Macroscopictrap Micro-trap Current~ 100 A Power ~ 1.5 kW Current<1 A Power < 10 W n = 10-100 Hz n = 1-100 kHz Ultra High Vacuum~ 10-11Torr High Vacuum~ 10-9Torr double MOT system: Laser power~ 500 mW single MOT system: Laser power~ 100 mW Large BEC 106atoms but production cycle> 1 min BEC 105atoms and production cycle~ 1 s

9. s+ s- s+ s+ s- s- Laser Coolingcloseto a surface

10. BEC on a chip • Planar Geometry  gold microstrips on silicon substrates Bwir (Iwir= 3A) Bbias= {0,3.3,1.2} Gauss |B| (Gauss) z (mm) Iwir= 3 A ; Bbias= {0,3.3,1.2} Gauss Iwir= 1 A ; Bbias= {0,3.3,1.2} Gauss |B| (Gauss) x (mm)

11. BEC on a chip

12. time [ms] action MOT in reflectionloading 10^8 atoms MOT transfer close to the chip (~1mm) CMOT + Molasses 5 x 10^7 atoms @ T ~ 10 μK Optical pumping Ancillarymagnetictrap (big Z wire) 20 x 10^6 atoms @ T ~ 12 μK Compression and transfer to the magnetictrap on chip (chip Z wire) 20 x 10^6 atoms @ T ~ 50 μK (~200 μm) Evaporation (big U under the chip) BEC with 30x10^3 atoms, Tc=0.5 μK End of the cycle 5000 BEC Generation Routine 5450 5485 5490 5740 8300 23000

13. lens atoms CCD camera Imagingcoldatoms

14. BEC on a chip MOT ~ 10^8 atoms Molassesphase ~ 5 x 10^7 atoms @ T ~ 15 uK First Magnetic Trap (big Z wire) ~ 20 x 10^6 atoms @ T ~ 12 uK Magnetic Trap on Chip (chip Z wire) ~ 20 x 10^6 atoms @ T ~ 50 uK Free fall of the BEC BEC ~ 20 x 10^3 atoms @ T < 0.5 uK

15. Outlook • Bose-Einsteincondensates on a microchip • AtomInterferometry • MultipathInterferometry on anAtomChip • Results and Conclusions

16. Atom Interferometer BEC – coherent form of matter , a wavepacket BEC 1 BEC 2 BEC 1,2 BEC 2 BEC 1,2 different spin states coupling mechanism BEC 1 BEC 1 Rabi pulse separation for measurement Stern-Gerlach experiment

17. BEC on a chip

18. Atomic Ramsey Interferometer- Theory - 2 Δ=ω 0 -ω ω ω0 Solve GPE for the BEC start from 1 mix two states let them evolve for time T Solve SE for 1 atom for the non-interacting BEC mix them up again

19. Rabi Oscillations Stern-Gerlach method Δ B mf=2 mf=2 mf=1 BEC mf=2 Tp time space - pulse BEC mf=1 Rabi frequency

20. Rabi Oscillation mf -2 -1 0 1 2 π/2 Rabi frequency ~ 50KHz

21. Experimental Scheme:Ramsey Interferometer π/2 π/2 mf=2 Δ B space mf=2 mf=1 mf=2 mf=1 time

22. Ramsey Interferometer Oscillation frequency = 1/RF = 1/650KHz = 1.5 μs

23. Outlook • Bose-Einsteincondensates on a microchip • AtomInterferometry • MultipathInterferometry on anAtomChip • Results and Conclusions

24. Parameters of the Interferometric Signal amplitude D’Ariano & Paris, PRA (1996) Resolution: Working range: background Sensitivity: Weihs et al., Opt. Lett. (1996)

25. Multi-path Interferometer

26. Multi-Path interferometer W W W W Funnyenougnfor N>3 the system can beaperiodicsincefrequencies are incommensurable Even more funthey are the solutionsof a complex Fibonacci Polynomial

27. Multi-Path interferometer Theredoesnotexist a p/2 pulse. Toobtain the best resolutionfrom the interferometeronehastooptimizepulse area

28. Multi-Path interferometer

29. Multi-Path interferometer

30. Outlook • Bose-Einsteincondensates on a microchip • AtomInterferometry • MultipathInterferometry on anAtomChip • Results and Conclusions

31. What can you use it for? Detection of a Light-Induced Phase Shift Polarisation σ+ Polarisation σ- Light-pulse detuning from F=2  F=3 was 6.8GHz.

32. Conclusions • We have demonstrated a compact time-domain multi-path interferometer on an atom chip • Sensitivity can be controlled by an RF pulse acting as a controllable state splitter. • Resolution superior to that of an ideal two-path interferometer. • Simultaneous measurement of multiple signals at the output enables a range of advanced sensing applications in atomic physics and optics • Integration of interferometer with a chip puts it into consideration for future portable cold-atom based measurement systems.

33. Thosewhoreallydidit Atom Chip Team our typical signal Ivan Herrera JovanaPetrovic Pietro Lombardi

34. Whodidit? A typical BEC JovanaPetrovic Ivan Herrera Pietro Lombardi