Linear Atom guide: building an atom laser and other experiments

1. Linear Atom guide: building an atom laser and other experiments Mallory Traxler April 2013

2. Motivation • Continuous atom laser • Continuous, coherent stream of atoms • Outcoupled from a BEC • Applications of atom lasers: • Atom interferometry • Electromagnetic fields • Gravitational fields • Precision measurement gyroscopes • Atom lithography

3. Overview • Guide α • Experimental apparatus • Experiments in guide α • Rydberg atom guiding • Design and manufacture of guide β • Improvements from guide α’s design • Outlook

4. guide :Experimental apparatus α

5. Guide Overview α

6. Level diagram:Rb 87

7. Primary & secondaryMagneto-optical traps • Φpmot≈3x109 s-1 • <vz,pmot>≈22 m/s • 2D+ MOT • Φmmot≈4.8x108 s-1 • 2.2 m/s to 2.9 m/s

8. Optical detection • Detect atoms at the end • Uses pulsed probe (23) and probe repumper (12) • Optimize atoms in the guide

9. Ion Imaging • Three lasers for excitation • Repumper to get back to bright state • 5S1/25P3/2 • 480 nm to 59D • Ionize • Voltages on electrode, guard tube, MCP direct ions upward to MCP for detection

10. Experiments in guide :Rydberg atom guiding α

11. Introduction to Rydberg Atoms • High n-principal quantum number • Data here with n=59 • Physically large • r~n2 • Very susceptible to electric fields • α~n7 • Strong interactions • Other Rydberg atoms • Blackbody radiation

12. Experimentaltiming • Excitation to 59D • Variable delay time, td • MI or FI • Camera gated over ionization duration

13. Observed phenomena • Penning ionization • Remote field ionization • Initial • Delayed • Thermal ionization • (Radiative decay) • Microwave ionization • Field ionization

14. Observed phenomena • Penning ionization • Remote field ionization • Initial • Delayed • Thermal ionization • (Radiative decay) • Microwave ionization • Field ionization

15. Observed phenomena • Penning ionization • Remote field ionization • Initial • Delayed • Thermal ionization • (Radiative decay) • Microwave ionization • Field ionization

16. Observed phenomena • Penning ionization • Remote field ionization • Initial • Delayed • Thermal ionization • (Radiative decay) • Microwave ionization • Field ionization

17. Observed phenomena • Penning ionization • Remote field ionization • Initial • delayed • Thermal ionization • (Radiative decay) • Microwave ionization • Field ionization

18. Observed phenomena • Penning ionization • Remote field ionization • Initial • Delayed • Thermal ionization • (Radiative decay) • Microwave ionization • Field ionization

19. Observed phenomena • Penning ionization • Remote field ionization • Initial • Delayed • Thermal ionization • (Radiative decay) • Microwave ionization • Field ionization

20. Observed phenomena • Penning ionization • Remote field ionization • Initial • Delayed • Thermal ionization • (Radiative decay) • Microwave ionization • Field ionization

21. Rydberg guiding Data • Vary td from 5 μs to 5 ms • τMI=700 μs • τ59D5/2=150 μs

22. FI: internal state evolution • State-selective field ionization • Different electric field needed for different states • 59D peak broadens • State mixing

23. Rydberg guiding recap • Rydberg atoms excited from ground state atoms trapped in guide • Observe Rydberg guiding over several millisecondsusing microwave ionization and state selective field ionization • Numerous phenomena from Rydberg atoms within the guide

24. guide :Design and progress β

25. Guide β • Improvements over guide α • Zeeman slower • No launching • Magnetic injection • Mechanical shutter

26. 1mot • Standard 6-beam MOT • Fed by Zeeman slower • Factor of 6.6 brighter • Expect closer to 10x

27. 2MOT chamber • Most complicated part of the design • 4 racetrack 2MOT coils • 8 injection coils • Built-in water cooling • Magnetic compression • Mechanical shutter

28. 2mot coils • 4 racetrack coils produce quadrupole magnetic field • Holes • Optical access • Venting of internal parts • Shutter • 2 locks for stationary shutter

29. Injection coil mount • 8 injection coils of varying diameters • Fits inside 2MOT coil package • Water cooling for all • Tapered inside and out

30. Steel piece, stationary shutter • Magnetic compression • Mount for waveplate-mirror • Stationary shutter

31. In-vacuum coils • Hand-turned on lathe • 2MOT coils on form • Injection coils directly on mount • Labeled with UHV compatible ceramic beads

32. Injection coils • High current power supply • Split off 2-3 A for each coil • Adiabatically inject atoms into the guide

33. Surface adsorption evaporative cooling • 21 equally spaced silicon surfaces • Bring guided atomic flow closer to these surfaces • Atoms not adsorbed onto surface rethermalize at lower temperature

34. Guide recap β • Fully constructed • Preliminary tests well on the way • Good transfer of atoms into the 2MOT • Need Zeeman slower and 2MOT working simultaneously to optimize

35. Experimental outlook

36. Short term outlook:Transverse cooling • Increase capture volume of Zeeman slower • Reduce transverse velocity by factor of x, increase density by factor of x2 • Most optics already in place

37. Longer term outlook:Potential Barrier • Potential barrier at the end of the guide • Form BEC upstream • Use coil to create potential • Study BEC loading dynamics, number fluctuations • Later use light shield barrier • Tunnel atoms through to make first continuous atom laser

38. Raithel Group • PI • Prof. Georg Raithel • Former Post Docs • Erik Power • Rachel Sapiro • Former Grad Students (on this project) • Spencer Olson • RahulMhaskar • Cornelius Hempel • Recent Ph.D. • Eric Paradis • Graduate Students • Andrew Cadotte • Andrew Schwarzkopf • David Anderson • Kaitlin Moore • NithiwadeeThaicharoen • Sarah Anderson • Stephanie Miller • Yun-Jhih Chen • Current Undergraduate • Matt Boguslawski • Former Undergrads • VarunVaidya • Steven Moses • Karl Lundquist

39. Picture summary