Day 3 Day 3 Day 3 Resonant photon excitation in EBIT Synchrotron - - PowerPoint PPT Presentation

Day 3

Day 3

Day 3

Resonant photon excitation in EBIT

• Synchrotron radiation (PETRAIII),
• Free-electron lasers (LCLS) ,

provide X-rays with high power and energy resolution

Resonant photon excitation in EBITs

• M. C. Simon et al.,

PRL 105 105 183001 (2010)

• V. Mäckel et al.,

PRL 107 107 143002 (2011)

• S. Bernitt et al.,

Nature 492 492, 225 (2012)

• J. K. Rudolph et al.,

PRL 111, 103002 (2013)

Visible M1 Ar13+ Soft X-ray photoionization Fe14+ FEL 800 eV Fe16+ Synchrotron 6 keV Fe24+, 13 keV Kr34+

photoions

Photon beams interact with trapped ions

LCLS, BESSY II, Petra III, lasers

|e |g  )

Compare transitions that depend differently on α

• Sensitivity coefficient q ~relativistic contributions
• HCI extremely sensitive: Frequency metrology on

forbidden transitions between nearly degenerate states (e. g., Ir17+ , Pr9+)

Search for a time-variation of with cold HCI

Enhanced sensitivity to  variation

Configuration crossings with charge state

Atoms and lowly charged ions Highly charged ions

• Re-arrangements of orbital energies with charge state
• Levels of different parity nearly degenerate at crossing
• Highest sensitivity
• J. C. Berengut et al., PRL 106

106, 210802 (2011)

• M1 clock transitions in monovalent

[panels (a) and (b)] and divalent (c) highly charged ions.

• A particular choice of nuclear spins in

panels (b) and (c) and hyperfine states forming clock transitions eliminates quadrupolar shifts.

• Predicted fractional accuracies below

the 10−20–10−21 level for all common systematic effects, such as blackbody radiation, Zeeman, ac-Stark, and quadrupolar shifts.

M1 Transitions in HCI as a Basis of Ultraprecise Optical Clocks, Yudin, Taichenachev and Derevianko, PRL 113 113, 233003 (2014)

Many ultra-stable M1 transitions available

large positive q small q large negative q

• ptical transitions

Ir17+: q ~ 740 000 cm‐1 Hg+: q ~ 52 200 cm‐1

• J. C. Berengut et al., PRL 106

106, 210802 (2011)

Level crossings in Ir17+

Level crossings at Ir17+ provide sensitivity

• With increasing charge

state, reordering of levels takes place

• 4f levels go below 5s at

Z≈77

• Levels of opposite parity

cross: 4f12 5s2, 4f13 5s, 4f14

• M1, E1, E2, M2, M3

transitions become possible.

• Several long lived

„ground states“ available.

Line identification through M1-scaling functions

• Comparison between theoretical and experimental scalings

yields identification E(Z)=A+B*Z+C*Z2

Windberger et al., PRL 114 114, 150801 (2015)

Line identification through g-factor fits

Windberger et al., PRL 114 114, 150801 (2015)

Magnetic field causes large Zeeman splitting providing an additional criterion for identification

• f the lines

Comparison between theories

* Berengut et al., PRL 106 106, (2011)

*

Windberger et al., PRL 114 114, 150801 (2015)

• Fock-space coupled cluster calculation (A. Borschevski) shows agreement

with experimental result at a level suitable for identification.

• Its deviations from experiment are smaller than the average separation

between spectral lines (as given by the green band).

Arrows: Black, identified M1 lines; magenta, tentatively identified E1;

• range, inferred M2/E3 clock transition; gray , previously identified.

Unconnected fine-structure levels taken from FSCC calculations.

New data on 4f 14, 4f 135s and 4f 125s2 for Ir17+

• H. Bekker et al., in preparation

M2/E3 clock transition at 1417 nm

Pr9+: four valence electrons (Sn-like)

5s25p2 3P0 5s25p4f 3G3 l=475 nm l=424 nm

t = 20 000 000 years!

t =58 s

M3 M3 q = 43000 cm-1 l=351 nm t = 0.003 s 5s25p2 3P1 M1 5s25p4f 3F2 Courtesy of M. S. Safronova

• Trapped ions are protected from collisional quenching and
• ffer extremely long lived transitions
• They may have several “ground states” usable as qubits

Highly charged ions: Optical clocks and applications in fundamental physics,

• M. G. Kozlov, M. S. Safronova, JRCLU, P. O. Schmidt, RMP 90

90, 045005 (2018)

Pr9+: The 5p-4f crossing

• H. Bekker, J. Berengut, submitted

Crossing of three configurations including same and

• pposite parities, M1 to M3 transitions available

Comparison between theories

• H. Bekker, J. Berengut, submitted

Experimental determination of all involved levels with Ritz-Rydberg method plus Zeeman

Hyperfine couplings change lifetimes

• H. Bekker, J. Berengut, submitted

Frequency of proposed 3P0→3G3 clock transition determined with accuracy sufficient for quantum-logic spectroscopy at ultra-high resolution

Highly‐charged ions as probes for

• strong relativistic effects,

large ionization energies  strong sensitivity to a change in

• need different electronic configurations

 optical transitions near level crossings

• hyperfine‐transitions sensitive to

System K (nm) Sr 0.06 699 Yb+ E2 0.91 436 Yb+ E3 ‐6 467 Hg+ ‐2.9 281.5 Al+ 0.01 267 Ir17+ T1 ‐20.6 ca. 267 Ir17+ T2 32.2 ca. 470 Cf16+* T1 75

• ca. 520

Cf16+* T2 ‐46

• ca. 653

Th* nuclear 8000 ca. 160 Δ Δ

• [J. Berengut et al., Phys. Rev. Lett. 105, 120801 (2010);
• J. C. Berengut et al., Phys. Rev. Lett. 106, 210802 (2011);
• J. C. Berengut et al., Phys. Rev. Lett. 109, 70802 (2012);
• J. C. Berengut et al., EPJ Web of Conferences 57, 2001 (2013);
• V. A. Dzuba et al., Phys. Rev. A 86, 54502 (2012);
• M. S. Safronova et al., Phys. Rev. A 90, 42513 (2014);
• M. S. Safronova et al., Phys. Rev. Lett. 113, 30801 (2014);
• V. A. Dzuba et al., Phys. Rev. A 91, 22119 (2015);
• V. A. Dzuba et al., arXiv:1508.0768 (2015);
• D. K. Nandy and B. K. Sahoo, Phys. Rev. A 94, (2016)]

• X-ray photon energies

1.5 ppm

• VUV photon energies

4 ppm

• Optical photon energies

0.3 ppm

• Lifetimes (ns… ms)

0.15 %

• Natural linewidths X-rays:

resolved Accuracy is 10 orders of magnitude lower than in frequency metrology

State of the art in the field of HCI Stone-age spectroscopy at the 10-6 level

Coulomb crystals with HCI for optical clock

Collaboration with PTB (Piet Schmidt): build an

• ptical clock with an HCI.

MPIK-PTB Collaboration, M. Schwarz, “Cryogenic Linear Paul Trap...”,

• Rev. Sci. Instrum. 83, 083115 (2012)

Laser cooling in Paul trap: Ion crystals

• Ion crystals (Be+) at T=5 mK

sympathetically cool HCI

• THCI =106 K

0.1 K

• Doppler width reduction
• Low polarizability of HCI

suppresses black-body and light shifts

• Improved clocks: search for

time-variation of α

• Cooling applicable to X-ray

laser spectroscopy

HCI

HCI HCI

CryPTEx: Cooling Tion down to 100 mK

The “Cryogenic Paul Trap Experiment“ was designed for sympathetic laser cooling of highly charged and molecular ions

Design, construction 2010 (M. Schwarz, F. Brunner), tests 2011, operation 2012

• M. Schwarz et al. RSI (2012); O. O.Versolato et al., Hyperfine Int. (2013)

4K trap accessible for HCI injection

• 16 access ports to 4K trap: lasers, imaging, atoms, ions
• External ion sources + in-trap photoionization
• Measured pressure 10-15 mbar
• “Effective” black-body radiation temperature ~7.6 K

Be He, H2 HCI Lasers Lasers

Built by MPIK Apprentice Mechanical Workshop

Be ion crystals four ions two ions imaging lens cooling laser spectroscopy laser trap electrodes atomic beam cryogenic shields ↔ 0.05

mm

spectroscopy laser ion crystal

Paul trap at 5 K

O.O.Versolato, et al. PRL (2013);

• A. K. Hansen et al, Nature (2014)

1 Ar13+ 3 Ar13+ ~ 20 Ar13+

Effects of trapping and cooling conditions

liquid phase Be+ ion cloud mixed phase Be+ ion cloud Cold Be+ Coulomb crystal

Nice crystals

HCI identification by image analysis

• The single HCI (here Ar13+) repels Be+ ions and

produces a hole in the Coulomb crystal

• Addressing a single ion in the trap with a focused

beam is possible due to large separation.

Lisa Schmöger et al., Science 347 347, 1233 (2015)

HCI cooling with a single Be+ ion

Lisa Schmöger et al., Science 347 347, 1233 (2015)

HCI production, deceleration, implantation

Lisa Schmöger et al., Science 347 347, 1233 (2015)