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Preparing Antihydrogen at Rest for Quantum Free-Fall Experiment in Linear Ion Trap

This project outlines the requirements and challenges involved in capturing, cooling, and manipulating antihydrogen ions at rest for precise quantum experiments. Experimental progress and challenges in ground state cooling and Doppler cooling are discussed.

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Preparing Antihydrogen at Rest for Quantum Free-Fall Experiment in Linear Ion Trap

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  1. Preparing antihydrogen at rest for the free fall in Laurent Hilico Jean-Philippe Karr Albane Douillet Vu Tran Julien Trapateau Ferdinand Schmidt Kaler Jochen Walz Sebastian Wolf 2014 – 2017 Bescool project WAG 13-15 November 2013 Bern

  2. Outline • H+ motion control requirements • Capture and cooling challenges • Experimental progress

  3. GBAR overview

  4. Last GBAR steps H H+ Capture and cooling by laser cooled Be+ ions Threshold Photodetachment l=1.7 µm Reaction chamber H at rest Recoil 0.23 m/s H+ g e+ 1 .. 6 keV Temperature 60 .. 300 eV 30 cm Accurate measurment of g < 1 % H initial velocity Dv0 < 0.8 m/s H+ 3 neV, 20 µK

  5. H with v0 < 1 m/s ? Ground state quantum harmonic oscillator w < 3 MHz m = 1.67 10-27 kg , Dv0 < 0.8 m/s Cooling challenges Cold trappedH+ Reaction chamber Capture + Cooling Trapped particule Temperature 3 neV 20 µK Kinetic energy 1 .. 6 keV Temperature 60 .. 300 eV 700 000 K ÷ 1010..11 Frontiers of Quantum world NIST D. Wineland Innsbruck R. Blatt Classical world

  6. Two Cooling Steps First step Capture and sympathetic Doppler cooling by laser cooled Be+ ions in the linear capture trap (Paul trap, r0 = 3.5 mm, W = 13 MHz) few mm H+ 313 nm laser 300 eV, T = 240 000 K T ÷ 3 109 > 10 000 laser cooled Be+ ions 100 neV, T ~ mK Second step Transfer and ground state cooling of a Be+/H+ ion pair in the precision trap F. Schmidt Kaler, S. Wolf , Mainz

  7. t H+ intake Ubiais=980 V time 0 V Capture efficiency First step Be+ laser cooled ions 1 keV H+ ions Biased linear RF Paul trap Output end-caps Input end-caps 1000… 0 V Versus initial temperature (eV) Versus intake delay t eV

  8. Sympathetic cooling time First step • Numerical simulation 500 Be+ and 20 H+ v t = 0 s Ec= 2 meV 313 nm laser t = 8 ms • Hotter H+ ions and larger ion clouds numerical challenge Work plan : Experimental tests with matter ions H2+ or H+

  9. Second step Precision trap – motional couplings Two coupled oscillators in an external potential x,y • z trapping DC potentials • x,y trapping RF effective potentials • Coulomb interaction coupling z H+ Be+ Newton equations equilibrium positions small oscillations in phase mode out of phase mode normal modes individual ion modes x, y, z 1D 3D T. Hasegawa, Phys. Rev. A 83, 053407 (2011) J. B. Wübbena, S. Amairi, O. Mandel, P.O. Schmidt, Phys. Rev. A 85, 043412 (2012)

  10. b12 z motion x,y motion mlc/msc Second step Precision trap – motional couplings Efficient sympathetic cooling mLC/mSC 1 b1 = 50 % b2 = 50 % mLC/mSC = 9/1 b1 = 99.996 % b2 = 0.872 % ?

  11. Doppler cooling in precision trap >> 20 µK

  12. Raman side band cooling w0-D+dhfs- wi w0-D Stimulated Raman transition Spontaneous Raman transitions H+ Be+ w0 D ~ tens of GHz 2P3/2 F=0, 1, 2, 3 3 laser freq. 2 beams F=1, 2 2P1/2 313.13 nm 2S1/2 n=2 dhfs= 1.25 GHz n=3 n=2 wvibr

  13. Raman side band cooling Second step Stimulated Raman transition no spontaneous emission coherent process Rabi oscillation D Population transfert probability Lamb Dicke parameter For n → n-1, p pulse duration n=2 ~ 10 ms < 1s n=3 n=2

  14. Experimental progress

  15. Capture trap design Jean-Philippe Karr Hot H+ RF 250 V at 13.3 MHz, r0 = 3.5 mm DC’s 2 .. 10 V 313 nm cooling laser Quadrupole guide 12 mm RF DC O V DC

  16. Transfer to precision trap Design: Sebastian Wolf, Mainz Capture trap Photodetachment l = 1.64 µm ~2 mm l = 313 nm Cooling Mainz implantation trap

  17. Vacuum vessel with cryopumping H+ Capture trap Precision trap

  18. Work plan 11/2013 12/2013 2013 Achieve the design Setup the cooling lasers 03/2014 12/2014 2014 Test with H2+ and H+ matter ions from the REMPI source Capture trap implementation Precision trap implementation Test with Be+ and Ca+ ions 06/2015 12/2015 2015 Evaluate sympathetic cooling times numerically & experimentally Transfer of precision trap to Paris, 03/2016 12/2016 2016 Be+ and H2+ transfered in precision trap Be+/H2+ ground state cooling

  19. Tests with a H2+ / H+ REMPI source 303 nm pulsed laser 3-4 mJ H2+ ions Ec = 50 eV dE ~ 10 meV H2 100 % efficiency H2+ ions Ec = 0 eV dE ~ 200 meV P=10-10 mb Injection into the quadrupole guide P=10-6 mb Ion creation P=10-8 mb Ion optics H+ Gbar H2+ metrology project HCI highly charged ions 40Ar13+, P. Indelicato, C. Szabo Synergies

  20. Conclusion • Capture of > 10 eV H+ and Doppler cooling in a linear Paul trap • Transfer to precision trap • Doppler and ground state cooling in precision trap OK OK PhD positions available • ANR BESCOOL • ITN ComiQ

  21. Can we improve the motional couplings ? Idea wcoul Efficient coupling w2 w1 Trapped ions w1 ~ w2 ~ 1.0 MHz wCoul ~ 100 kHz z12eq Coulomb coupling z12eq < 40 µm wz 2 ~ 3 wz1 with m1 = 9, m2 =1 Single well poor couplings wx 2 ~ 9 wx1 Double well structure with very small electrodes ? Possible solution

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