A new experimental apparatus for quantum atom optics

Transcription

1 A new experimental apparatus for quantum atom optics Andreas Hüper, Jiao Geng, Ilka Kruse, Jan Mahnke, Wolfgang Ertmer and Carsten Klempt Institut für Quantenoptik, Leibniz Universität Hannover

2 Outline I. Motivation: Accessible physics II. Experimental techniques III. Our approach 2

3 Sub-shot-noise interferometry Standard Quantum Limit (SQL): θ~ 1 N KRb Heisenberg Limit: θ~ 1 N 3

4 From optical parametric down-conversion to spin dynamics 87 Rb F=1 m F = Optical parametric down-conversion Coherent pump Non-linear crystal Signal and idler beam Spinor Bose-Einstein condensate 87 Rb BEC in m F =0 Spin dynamics Atoms in m F =±1 4

5 Twin-Fock state interferometry [1] Lücke et al. Science 11, Vol. 334 no pp , 2011 [2] Lücke PhD Thesis,

6 Counting uncertainty for twin Fock state interferometry Between 6400 to 7600 atoms [1] Lücke et al. Science 11, Vol. 334 no pp , 2011 [2] Lücke PhD Thesis,

7 Single-Particle Fock State Wigner Function of n-particle Fock state: W x, p = 2 π 1 n L n (4(x 2 + p 2 ))e 2(x2 +p 2 ) [1] Lvovsky et al. Physical Review Letters, Vol 87, No 5, 2001 [2] Introductionary Quantum Optics, C.C. Gerry & P. L. Knight 7

8 Single-Particle Fock State for photons [1] Lvovsky et al., Physical Review Letters, Vol 87, No 5,

9 Few-Particle Fock State for photons 2 3 [1] Cooper et al., Optics Express, Vol 21, No 5,

10 Outline I. Motivation: Accessible physics a. Improved sub-shot-noise interferometry b. Negative Wigner Function of the 1 -Fock state II. Experimental techniques III. Our approach 10

11 MOTs as a tool for counting atoms 11

12 MOTs as a tool for counting atoms Photons per atom: n p = R sc ηt Photon shot noise: N a n p < 1 Interrogation t 100 ms Up to 1200 atoms in single atom detection m F =+1 m F =0 m F =-1 [1] Hume et al. Physical Review Letters, 111, ,

13 Double MOT with a Light Barrier 24µm Pulsed 125kHz 120 ms integration time Up to 470 atoms per site [1] Stroescu et al., PRA 91, ,

14 Outline I. Motivation: Accessible physics a. Improved sub-shot-noise interferometry b. Negative Wigner Function of the 1 -Fock state II. Experimental techniques a. In magneto-optical traps III. Our approach 14

15 Design Goals 1. Create a 87 Rb BEC in a few seconds a. Optical dipole trap b. Micro chip trap 2. Detect multiple modes a. MOT with a light barrier b. Multiple MOTs (with a chip) 3. with single atom counting precision Large NA detection Stray light suppression Resolve light barrier MOT 4. Maximize optical access 5. Reduce magnetic field noise [1] [1] Clément et al., PRA, 79, ,

16 The Experimental Setup ODT 3D-MOT Detection NA 3D MOT coils Quadrupol coils 16

17 Coil Design Gradient of ~300 G/cm for efficient transfer to ODT Two half circles to avoid large eddy currents Optical access of 3D MOT beams with a diameter of d=20 mm 4 Layers, with 2x29 and 2x24 windings About 1.8-2kW at 150 A Water cooling on top and bottom 17

18 Detection Optics Large NA (NA = 0.4, i.e. α = 23.5 deg) Out of Chamber Only commercially available lenses Stray light reduced 18

19 Detection Optics Magnification: ~ 18 Resolution: ~1.2 µm 19

20 Detection: Scattered Light Background incoming MOT light R 1 R2 R 0 R 3 to the detection 20

21 Detection: Scattered Light Background Amount of incident photons in MOT beam: N ph s Multiple reflections inside the chamber: R n ( ) n Surface quality and scattering rate: P sc Out-of-focus supression by pinhole: P pin Numerical aperture: NA N bkg s N bkg (t = 100 ms) 25 σ phsn (t = 100 ms)

22 Next Steps in 2016 Component February March April May June July Coil assembly Finalize design wind, test with water cooling µmetal Shield Depends on coil design Finalize design and order Hopefully arrives Test shielding and stability Glass chamber Frame is ready Hopefully arrives Bake and pump Special 4 way vacuum cross Hopefully arrives Vacom parts MOT laser system Optical dipole trap Light sheet system arrived Order and slight rebuild Build test setup for intensity and position stabilization Design, pick components Detection optics ready to order (fast) arrive Test imaging of lens system 22

23 The Team Wolfgang Ertmer Carsten Klempt Andreas Hüper Jiao Geng Jan Mahnke Ilka Kruse Thank you for your attention! 23