The World s Smallest Extreme Laboratories:

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1 The World s Smallest Extreme Laboratories: Probing QED with Highly Charged Ions. Joan Marler Clemson University

2 Outline About HCIs About Ion trapping Precision spectroscopy with HCIs

3 Highly Charged Ions Hydrogen

4 Highly Charged Ions Hydrogen Neon

5 Highly Charged Ions Hydrogen Neon

6 Highly Charged Ions Hydrogen Highly Charged Neon

7 Highly Charged Ions Hydrogen Highly Charged Neon

8 Highly Charged Ions Hydrogen Highly Charged Neon

9 Highly Charged Ions Hydrogen Ni +27 Gillaspy (2001) J Phys B. Highly Charged Ions

10 Why is this interesting? structure

11 Why is this interesting? structure There is no vacuum

12 Why is this interesting? structure There is no vacuum Electric field of V cm -1

13 Why is this interesting? structure There is no vacuum Electric field of V cm -1 Low particle number -> theoretically tractable?

14 Why is this interesting? energy ionization Hydrogen 0eV eV

15 Why is this interesting? energy ionization Hydrogen H-like Nickel (+27) 0eV 0eV eV - 11,000eV

16 Why is this interesting? energy ionization Hydrogen H-like Nickel (+27) 0eV 0eV eV

17 Why is this interesting? energy electronic excitation wavelength(nm) 1s 2-1s2s Infrared Visible UV X-ray 1s2s-1s2p higher energy He-like Z (Nuclear Charge) Gillaspy (2001) J Phys B. Highly Charged Ions

18 Why is this interesting? experimentally

19 Why is this interesting? experimentally ``easy to accelerate, decelerate and contain

20 Why is this interesting? experimentally ``easy to accelerate, decelerate and contain suppressed effects from external fields

21 Why is this interesting? experimentally ``easy to accelerate, decelerate and contain suppressed effects from external fields potential energy > kinetic energy

22 Why are they interesting?

23 Why are they interesting? most of the visible universe is HCIs

24 Why are they interesting? most of the visible universe is HCIs dense/hot plasmas= Fusion

25 Why are they interesting? most of the visible universe is HCIs fundamental physics dense/hot plasmas= Fusion

26 Why are they interesting? most of the visible universe is HCIs fundamental physics dense/hot plasmas= Fusion

27 Because of its extreme complexity, most physicists will be glad to see the end of QED Dirac 1937

28 Quantum Electrodynamics (QED) most precisely tested theory describing the interaction of matter and light. predicts electronic structure of atoms E H like = α(αz)3 m e F(F + 1) I(I + 1) J(J + 1) n 3 g I m e c 2 m p 2J(J + 1)(2L + 1) ] [A 1s (αz)(1 δ 1s )(1 ϵ 1s ) + χ rad, Schmidt (2014) Hyperfine Interactions

29 Quantum Electrodynamics (QED) comparison between experiment and theory provides stringent tests on relative contributions to QED calculations, fundamental constants values, and time variations in the fundamental constants.

30 Precision measurements with HCIs Previous x-ray in EBIT

31 Precision measurements with HCIs Previous x-ray Visible Transitions commercial lasers commercial detectors in EBIT

32 Precision measurements with HCIs Previous x-ray Visible Transitions commercial lasers commercial detectors in EBIT Paul trap mk temperatures collisionless environment

33 Visible lines in HCIs Fine structure transitions Hyperfine transitions Vogel and Quint (2009) J Phys B

34 Visible lines in HCIs Fine structure transitions Hyperfine transitions Vogel and Quint (2009) J Phys B

35 Visible lines in HCIs Fine structure transitions Hyperfine transitions Vogel and Quint (2009) J Phys B B-like or C-like low to mid Z ions

36 Expected Outcomes QED contributions are enhanced in HCIs, so at precisions routinely achieved with trapped single-ion spectroscopy or lower, QED contributions can be verified Precision measurements on isotopes to isolate nuclear effects Use these results to test time variation in fine structure constant.

37 Experimental Approach Electron Beam Ion Trap rf Paul trap Putting it together

38 Experimental Approach Electron Beam Ion Trap rf Paul trap Putting it together

39 Electron Beam Ion Trap (EBIT) HCIs Electron beam high energy and high current electron beam magnetically confined. Trap electrodes Magnetic field coil electron beam traps positive ions and continues to ionize them.

40 Electron Beam Ion Trap (EBIT) Time and energy of electron beam determines the final charge state of the trapped ions. Gillaspy (2001) J Phys B. Highly Charged Ions

41 CU EBIT Trap plus Beamline

42 CU EBIT

43 CU EBIT Endre Takacs

44 CU EBIT Endre Takacs Chad Sosolik

45 Experimental Approach Electron Beam Ion Trap rf Paul trap Putting it together

46 Linear rf Paul Trap UDC Urf cos Ωrft UDC

47 Laser Cooling P D S Difference in photon energy comes from the kinetic energy of the atom. After many cycles the atom is slowed (T~mK)

48 Laser Cooling CCD Image from Aarhus University Difference in photon energy comes from the kinetic energy of the atom. After many cycles the atom is slowed (T~mK)

49 Coulomb Crystals The spatially ordered state formed when ions are trapped and cooled below a critical temperature. Typical properties 2700 ions 100 µm Temperature: 10mK Number of ions: 1-100,000 Ion density: 10 8 /cm 3 Ion storage time: >hours 6400 ions 100 µm Images from University of Aarhus

50 Coulomb bicrystals Sympathetic cooling allows for multiple cold species with only direct laser cooling of one. 40 Ca + ions 44 Ca + ions m 44 >m 40! r44 <! r40 Image from University of Aarhus

51 Experimental Approach Electron Beam Ion Trap rf Paul trap Putting it together

52 Putting it together HCIs Electron beam Trap electrodes Magnetic field coil Electron Beam Ion Trap rf Trap *Note: not to scale.

53 Putting it together HCIs Electron beam Trap electrodes Magnetic field coil Electron Beam Ion Trap rf Trap *Note: not to scale.

54 Spectroscopy on Trapped HCIs Advantages HCIs Electron beam Trap electrodes Magnetic field coil Doppler free spectroscopy Sympathetic cooling Long interrogation times Improved optical access

55 Spectroscopy with Highly Charged Ions Heidelberg EBIT CryPTEx Schmoger et al., Science (2015)

56 HCIs in an rf trap 20 HCIs ( 40 Ar 13+ ) and Be + s 1 HCI ( 40 Ar 13+ ) and 29 Be + 1 HCI ( 40 Ar 13+ ) and3 Be + Schmoger, Science (2015)

57 First re-trapping in rf trap Schmoger, Science (2015)

58 The next step Quantum Logic Spectroscopy Laser Spectroscopy that also takes advantage of the motional modes of the trap to enhance small signals. Schmidt et al., Science (2005)

59 Summary Highly Charged Ions Strong contributions to astrophysical and fusion spectra Test of QED predictions in the strong field Visible Spectroscopy precision lasers available for spectroscopy visible spectra can be observed easily earth based telescopes and in fusion machines Retrapping long trapping time, collisionless environment; mk temperatures; excellent localization,

60 The team Steve Bromley Joshua Hanson Corey Ahl Sean Buechele Ben Slimmer

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