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

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

GBAR overview

by laser cooled Be+ ions 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 g H+ 1 .. 6 keV Temperature 60 .. 300 eV e+ 30 cm Accurate measurment of g < 1 % H initial velocity Dv0 < 0.8 m/s H+ 3 neV, 20 µK

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

> 10 000 laser cooled Be+ ions 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) H+ few mm 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

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

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+

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

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

Doppler cooling in precision trap >> 20 µK

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 2P1/2 F=1, 2 313.13 nm 2S1/2 n=2 dhfs= 1.25 GHz n=3 n=2 wvibr

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 Single ion b1 = 1 3 modes t ~ 100 µs /n/mode Be+/H+ b1z = 0.18 2 modes x 5 b1x,y = 0.0872 4 modes x 15 ~ 10 ms < 1s n=3 n=2

Experimental progress

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

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

Vacuum vessel with cryopumping H+ Capture trap Precision trap

Work plan 2013 2014 2015 2016 Evaluate sympathetic cooling times 11/2013 12/2013 2013 Achieve the design Setup the cooling lasers 03/2014 12/2014 2014 Capture trap implementation Test with H2+ and H+ matter ions from the REMPI source 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

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

PhD positions available 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

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