Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Ruprecht-Karls-Universität Heidelberg eBooks

Detection Electronics Design and First Observation of Bound-Electron Spin Transitions at the ALPHATRAP g-Factor Experiment

Weigel, Andreas

Published Jan 1, 2019• 0 citations
Publisher

Abstract

ALPHATRAP is a Penning-trap based experiment located at the Max-Planck-Institut für Kernphysik (MPIK). It is dedicated to the exploration of ground-state properties of heavy, highly charged ions (HCI). The major goal of the ALPHATRAP \nexperiment are high precision measurements of the bound-electron g-factor. The comparison of the experimental result with recent theoretical calculations will not only serve as a sensitive test of bound-state quantum electrodynamics (BS-QED) but also yields a new approach for the determination of fundamental constants such as the electron mass or the fine structure constant. The measurement of the bound-electron g-factor of a single HCI is performed in an optimized cryogenic double Penning-trap setup, utilizing the continuous Stern-Gerlach effect. For injection of externally produced HCI up to 208Pb81+ the ALPHATRAP experiment is \ncoupled to various ion sources, including the Heidelberg Electron-Beam Ion Trap. \nThis thesis describes the setup and preparation of the ALPHATRAP experiment on its way towards its first g-factor measurement. In this context a new highly sensitive detection system was implemented and successfully tested. This enabled a first commissioning of the whole apparatus with in situ generated HCI as well as HCI injected through the room temperature beamline. The first-time integration \nof an externally operable cryogenic valve allowed for excellent vacuum conditions with long ion storage times. The implementation of typical ion detection and manipulation techniques was demonstrated by characterization measurements of the detection system and the trapping fields. The commissioning culminated in the first direct observation of induced bound-electron spin transitions at the \nALPHATRAP experiment.

DOI
10.11588/heidok.00025998

Related papers

Towards Laser Cooling of Beryllium Ions at the Alphatrap Experiment

Sandro Kraemer

Alphatrap is a Penning-trap experiment aiming for the test of bound-state quantum electrodynamics (QED) by measuring the g-factor of electrons bound in highly charged ions up to hydrogen-like 208Pb81+. The high atomic number Z allows a test of boundstate QED under highest field strengths. Cold ions are necessary for high-precision measurements revealing the small additional effect of QED. As a novel development, laser cooling of beryllium ions will be used to sympathetically cool highly charged ions. The lower achievable temperatures are expected to further increase the precision of the measurement. Additionally, new measurement schemes such as simultaneous g-factor measurements on Coulomb crystallized ion pairs become feasible. In the context of this thesis, a concept for implementation of laser cooling at the Alphatrap experiment using 313nm light was developed. The experiment specific requirements on laser cooling in a Penning trap and sympathetic cooling are discussed and the results of the commissioning of the laser system are presented.

•Jan 1, 2017•0 citations

Investigation of a Novel Method for Sympathetic Laser Cooling of Highly Charged Ions in a Penning Trap

F.J.W. Hahne

The Penning trap experiment Alphatrap tests quantum electrodynamics via g- factor measurements of bound electrons in highly charged ions (HCI). The precision of the measurements can be improved by cooling the HCI. This thesis describes a novel and versatile method to sympathetically cool HCIs with laser-cooled beryllium ions efficiently in high-precision Penning traps. The method is based on increasing the coupling of two ions stored in separate penning traps by adding an electrical tank circuit. In a proof of principle measurement this was demonstrated using a 84Kr23+ and 40Ar11+ ion: first, we saw an avoided crossing of the ion modes, and second, we showed a Rabi oscillation in the energy transfer. Our coupling technique enables active control of the coupling strength between the ions, so that a coupling time of τ = 0:856(16) s was achieved. We see this as a possible tool to efficiently cool a wide range of ion species. In addition, an active beam stabilization system was installed to reduce fluctuations of the cooling laser beam position and orientation, and to improve the alignment of the laser with respect to the beryllium ions. This system was calibrated and geometric losses of the laser transmission through our Penning trap setup were estimated.

•Jan 1, 2020•0 citations

The g-factor of the bound electron in hydrogenic ions

W. Quint

We report on the measurement of the g-factor of the electron bound in an atomic ion. A single hydrogenic ion (12C5+) is stored in a Penning trap. The electronic spin state of the ion is monitored via the continuous Stern-Gerlach effect in a quantum non-demolition measurement. Quantum jumps between the two spin states (spin up and spin down) are induced by a microwave field at the spin precession frequency of the bound electron. The g-factor of the bound electron is obtained by varying the microwave frequency and counting the number of spin flips for a fixed time interval. Applications of the continuous Stern-Gerlach effect include high-accuracy tests of bound-state quantum electrodynamics (QED), the measurement of the atomic mass of the electron, the determination of the fine structure constant α, and the measurement of nuclear g-factors.

AIP conference proceedings•Jan 1, 2001•1 citation

Observation of the Continuous Stern-Gerlach Effect on an Electron Bound in an Atomic Ion

Nikolaus Hermanspahn, Hartmut Häffner, H. -Jürgen Kluge +4 more

We report on the first observation of the continuous Stern-Gerlach effect on an electron bound in an atomic ion. The measurement was performed on a single hydrogenlike ion ( 12C5+) in a Penning trap. The measured g factor of the bound electron, g = 2.001 042(2), is in excellent agreement with the theoretical value, confirming the relativistic correction at a level of 0.1%. This proves the possibility of g-factor determinations on atomic ions to high precision by using the continuous Stern-Gerlach effect. The result demonstrates the feasibility of conducting experiments on single heavy highly charged ions to test quantum electrodynamics in the strong electric field of the nucleus.

Physical Review Letters•Jan 17, 2000•113 citations

Coulomb crystals in a cryogenic Paul trap for sympathetic cooling of molecular ions and highly charged ions

A. Windberger, M. Schwarz, Oscar O. Versolato +11 more

Electron beam ion traps used for spectroscopy of highly charged ions (HCI) produce a deep trapping potential leading to high temperatures of the stored ions, and thus limiting the achievable spectral resolution. A novel device at the Max-Planck-Institut für Kernphysik, the Cryogenic linear Paul Trap Experiment (CryPTEx), attached to an electron beam ion trap, provides a new experimental platform to overcome these limitations. The trap assembly operates at a temperature of 4 K and offers optical access for quantum manipulation and imaging of the trapped ions. Since forbidden optical transitions in HCI do not support direct laser cooling, sympathetic cooling with Coulomb crystals of singly charged ions such as Be+ or Mg+ will be applied in order to reach the natural linewidth of optical forbidden transitions in HCI of interest. With the added advantage of long ion trapping times resulting from residual gas pressures of H2 at 4 K below 10−15 mbar, CryPTEx has been commissioned in collaboration with the Ion Trap Group in Århus using rovibrationally cooled MgH+ ions. Strong suppression of the black body radiation at the trap center, ion storage times of about 28 hours, and largely enhanced population of the rovibrational ground state were achieved.

AIP conference proceedings•Jan 1, 2013•4 citations

The magnetic moment anomaly of the electron bound in hydrogen-like oxygen16O7

J Verd, Thomas Beier, S Djeki +6 more

The measurement of the g -factor of the electron bound in a hydrogen-like ion is a high-accuracy test of the theory of quantum electrodynamics (QED) in strong fields. Here we report on the measurement of the g -factor of the bound electron in hydrogen-like oxygen ( 16 O 7+ ). In our experiment a single highly charged ion is stored in a Penning trap. The electronic spin state of the ion is monitored via the continuous Stern–Gerlach effect in a quantum non-demolition measurement. Quantum jumps between the two spin states (spin up and spin down ) are induced by a microwave field at the spin precession frequency of the bound electron. The g -factor of the bound electron is obtained by varying the microwave frequency and counting the number of spin flips. The comparison of our experimental values for the g -factor of the bound electron with the theoretical values shows excellent agreement and confirms the recent non-perturbative QED calculations.

Journal of Physics B Atomic Molecular and Optical Physics•Jan 24, 2003•13 citations
ALPHATRAP is a Penning-trap based experiment located at the Max-Planck-Institut für Kernphysik (MPIK). It is dedicated to the exploration of ground-state properties of heavy, highly charged ions (HCI). The major goal of the ALPHATRAP \nexperiment are high precision measurements of the bound-electron g-factor. The comparison of the experimental result with recent theoretical calculations will not only serve as a sensitive test of bound-state quantum electrodynamics (BS-QED) but also yields a new approach for the determination of fundamental constants such as the electron mass or the fine structure constant. The measurement of the bound-electron g-factor of a single HCI is performed in an optimized cryogenic double Penning-trap setup, utilizing the continuous Stern-Gerlach effect. For injection of externally produced HCI up to 208Pb81+ the ALPHATRAP experiment is \ncoupled to various ion sources, including the Heidelberg Electron-Beam Ion Trap. \nThis thesis describes the setup and preparation of the ALPHATRAP experiment on its way towards its first g-factor measurement. In this context a new highly sensitive detection system was implemented and successfully tested. This enabled a first commissioning of the whole apparatus with in situ generated HCI as well as HCI injected through the room temperature beamline. The first-time integration \nof an externally operable cryogenic valve allowed for excellent vacuum conditions with long ion storage times. The implementation of typical ion detection and manipulation techniques was demonstrated by characterization measurements of the detection system and the trapping fields. The commissioning culminated in the first direct observation of induced bound-electron spin transitions at the \nALPHATRAP experiment.
Alphatrap is a Penning-trap experiment aiming for the test of bound-state quantum electrodynamics (QED) by measuring the g-factor of electrons bound in highly charged ions up to hydrogen-like 208Pb81+. The high atomic number Z allows a test of boundstate QED under highest field strengths. Cold ions are necessary for high-precision measurements revealing the small additional effect of QED. As a novel development, laser cooling of beryllium ions will be used to sympathetically cool highly charged ions. The lower achievable temperatures are expected to further increase the precision of the measurement. Additionally, new measurement schemes such as simultaneous g-factor measurements on Coulomb crystallized ion pairs become feasible. In the context of this thesis, a concept for implementation of laser cooling at the Alphatrap experiment using 313nm light was developed. The experiment specific requirements on laser cooling in a Penning trap and sympathetic cooling are discussed and the results of the commissioning of the laser system are presented.
The Penning trap experiment Alphatrap tests quantum electrodynamics via g- factor measurements of bound electrons in highly charged ions (HCI). The precision of the measurements can be improved by cooling the HCI. This thesis describes a novel and versatile method to sympathetically cool HCIs with laser-cooled beryllium ions efficiently in high-precision Penning traps. The method is based on increasing the coupling of two ions stored in separate penning traps by adding an electrical tank circuit. In a proof of principle measurement this was demonstrated using a 84Kr23+ and 40Ar11+ ion: first, we saw an avoided crossing of the ion modes, and second, we showed a Rabi oscillation in the energy transfer. Our coupling technique enables active control of the coupling strength between the ions, so that a coupling time of τ = 0:856(16) s was achieved. We see this as a possible tool to efficiently cool a wide range of ion species. In addition, an active beam stabilization system was installed to reduce fluctuations of the cooling laser beam position and orientation, and to improve the alignment of the laser with respect to the beryllium ions. This system was calibrated and geometric losses of the laser transmission through our Penning trap setup were estimated.
We report on the measurement of the g-factor of the electron bound in an atomic ion. A single hydrogenic ion (12C5+) is stored in a Penning trap. The electronic spin state of the ion is monitored via the continuous Stern-Gerlach effect in a quantum non-demolition measurement. Quantum jumps between the two spin states (spin up and spin down) are induced by a microwave field at the spin precession frequency of the bound electron. The g-factor of the bound electron is obtained by varying the microwave frequency and counting the number of spin flips for a fixed time interval. Applications of the continuous Stern-Gerlach effect include high-accuracy tests of bound-state quantum electrodynamics (QED), the measurement of the atomic mass of the electron, the determination of the fine structure constant α, and the measurement of nuclear g-factors.
We report on the first observation of the continuous Stern-Gerlach effect on an electron bound in an atomic ion. The measurement was performed on a single hydrogenlike ion ( 12C5+) in a Penning trap. The measured g factor of the bound electron, g = 2.001 042(2), is in excellent agreement with the theoretical value, confirming the relativistic correction at a level of 0.1%. This proves the possibility of g-factor determinations on atomic ions to high precision by using the continuous Stern-Gerlach effect. The result demonstrates the feasibility of conducting experiments on single heavy highly charged ions to test quantum electrodynamics in the strong electric field of the nucleus.
Electron beam ion traps used for spectroscopy of highly charged ions (HCI) produce a deep trapping potential leading to high temperatures of the stored ions, and thus limiting the achievable spectral resolution. A novel device at the Max-Planck-Institut für Kernphysik, the Cryogenic linear Paul Trap Experiment (CryPTEx), attached to an electron beam ion trap, provides a new experimental platform to overcome these limitations. The trap assembly operates at a temperature of 4 K and offers optical access for quantum manipulation and imaging of the trapped ions. Since forbidden optical transitions in HCI do not support direct laser cooling, sympathetic cooling with Coulomb crystals of singly charged ions such as Be+ or Mg+ will be applied in order to reach the natural linewidth of optical forbidden transitions in HCI of interest. With the added advantage of long ion trapping times resulting from residual gas pressures of H2 at 4 K below 10−15 mbar, CryPTEx has been commissioned in collaboration with the Ion Trap Group in Århus using rovibrationally cooled MgH+ ions. Strong suppression of the black body radiation at the trap center, ion storage times of about 28 hours, and largely enhanced population of the rovibrational ground state were achieved.
The measurement of the g -factor of the electron bound in a hydrogen-like ion is a high-accuracy test of the theory of quantum electrodynamics (QED) in strong fields. Here we report on the measurement of the g -factor of the bound electron in hydrogen-like oxygen ( 16 O 7+ ). In our experiment a single highly charged ion is stored in a Penning trap. The electronic spin state of the ion is monitored via the continuous Stern–Gerlach effect in a quantum non-demolition measurement. Quantum jumps between the two spin states (spin up and spin down ) are induced by a microwave field at the spin precession frequency of the bound electron. The g -factor of the bound electron is obtained by varying the microwave frequency and counting the number of spin flips. The comparison of our experimental values for the g -factor of the bound electron with the theoretical values shows excellent agreement and confirms the recent non-perturbative QED calculations.