Max Planck-RIKEN-PTB Center for

Modern atomic clocks are among the most accurate measurement tools. They are the basis of advanced technology like the GPS system. The invention of the frequency comb opened the path to atomic clocks using optical transitions in trapped, single, highly charged ions (HCI).
In a recent article published in "Physical Review Letters" members of Klaus Blaum's division report on the identification of a metastable electronic state in highly charged lead ions (Nb-like ²⁰⁸Pb⁴¹⁺) which could be used as a clock state. The Penning-trap mass spectrometer PENTATRAP was used to directly determine the excitation energy of the metastable state in Pb⁴¹⁺ ions to be 31.2(8) eV. With a fractional mass uncertainty of 4·10^–12 this is one of the most precise mass measurements to date.
The experimental work was combined with a theoretical work from the division of Christoph Keitel at MPIK and Paul Indelicato from the Sorbonne University, in which the transition energy was theoretically determined with two extensive, partially different ab initio multi-configuration Dirac-Hartree-Fock calculations.

Please read more in the article ... >

Further information also in the press release of the MPIK 

They have done a good job, and their cooperation will be continued: After a successful review, the German-Japanese Center for Time, Constants and Fundamental Symmetries (TCFS) can start its second term. It will continue to strengthen the collaboration among German and Japanese institutes to advance most sensitive instruments for fundamental measurements in atomic and nuclear physics, antimatter and dark matter research, quantum optics and metrology. Three partners – the Max Planck Institutes for nuclear physics (MPIK) and for quantum optics (MPQ), the National Metrology Institute of Germany (PTB) and the Japanese flagship research institution RIKEN – will fund the centre in equal amounts with a total of around €7.5 million for an additional five years, starting in January 2024.

Please also read the related press release of the MPIK .

The Helium isotope ³He plays an important role for modern physics, particularly fundamental physics, e.g. sensitive tests of the bound state QED theory and muon g-2 experiments as well as for chemistry, medicine and other scientific fields.
In magnetometry, ³He nuclear magnetic resonance (NMR) probes allow for measurements of the absolute magnetic field with higher accuracy and serve as a new standard for ultra-sensitive absolute magnetometry.

In a recent article published in "Nature", researchers of our "Stored and Cooled Ions" division, University Mainz and RIKEN report the first direct measurements of the bound electron g-factor and nuclear g-factor of ³He⁺ with a relative precision of 10^–10. The accuracy of the ³He⁺ zero-field ground-state hyperfine splitting value (magnetic interaction of electron and nucleus) could be improved by two orders of magnitude.
The precision measurements were performed in a novel Penning-trap system. The system is placed in the homogeneous field of a 5.7 T superconducting magnet and consists of a precision trap (PT) and an analysis trap (AT) with a spatially separated strong magnetic inhomogeneity.

Please read more in the "Nature" article ... >

Further information also in the press releases of the "Stored and Cooled Ions Division" , the MPIK  (idw ) and the MPG .

An innovative particle cooling technique of the BASE collaboration has been selected to be among the Physics World Top 10 Breakthroughs in 2021 .

In 2021, former member of Klaus Blaum's division Dr. Matthew Bohman and the BASE collaboration  demonstrated the first sympathetic cooling of a single proton using a cryogenic two-Penning-trap system in "Nature"  (see our news of 25.08.21). To this end, the single proton was stored in a proton trap and a cloud of Be⁺ ions in a separate beryllium trap. The coupling was realized by connecting the two Penning traps to a superconducting cryogenic LC circuit with resonance frequency near their axial frequencies. This new cooling technique allows to reach proton temperatures far below the environment temperature. In the demonstration measurement, the proton temperature was reduced by 85%, from 17 K environment temperature to 2,6 K.

The novel sympathetic laser-cooling technique will enable enhanced precision experiments of any charged species at lower temperatures. In particular, it can be readily applied to cool protons and antiprotons in the same large macroscopic traps that enable precision measurements of the charge-to-mass ratio and g-factor. This will allow for improved precision in matter-antimatter comparisons and dark matter searches, performed by the BASE collaboration.

Please also read the related press release of the MPIK .

Peter Micke, award winner of the SAMOP Dissertation Prize 2021.
© PTB

For his dissertation and lecture entitled "Quantum Logic Spectroscopy of Highly Charged Ions", our former PostDoc Peter Micke has been awarded the Dissertation Prize 2021  of the Section Atoms, Molecules, Quantum Optics and Plasmas (SAMOP) of DPG.

We cordially congratulate Dr. Peter Micke on receiving this distinction of his scientific work.

Please read more in the MPIK Press Release .

Klaus Blaum, award winner of the Otto Hahn Prize 2021.
© Stefanie Aumiller / Max Planck Society

Our center co-director Prof. Klaus Blaum has been selected to receive the Otto Hahn Prize 2021. Klaus Blaum is honored for his outstanding research in the field of precision physics and measurement technology that expands our knowledge of the fundamental properties of the constituents of the matter surrounding us.

Since 2005, the Otto Hahn Prize  has been awarded jointly by the City of Frankfurt am Main , the Gesellschaft Deutscher Chemiker  (GDCh, German Chemical Society) and the Deutsche Physikalische Gesellschaft  (DPG, German Physical Society). The prize is named after the Frankfurt-born scientist Otto Hahn, who discovered nuclear fission and won the Nobel Prize in Chemistry in 1944.
According to its statute, the Otto Hahn Prize serves to "promote science, especially in the fields of chemistry, physics and applied engineering through the recognition of outstanding scientific achievements". It consists of a gold medal and a prize of 50,000 euros. The prize is awarded every two years with a ceremony in St. Paul’s Church, Frankfurt am Main, Germany, alternating each time between physics and chemistry.

The award ceremony of the Otto Hahn Prize 2021 will take place on November 5, 2021 in St. Paul’s Church, Frankfurt am Main, Germany.

We cordially congratulate Klaus Blaum on receiving this prestigious scientific award.

Please read more in the following press releases:

• MPIK Heidelberg 
• City of Frankfurt am Main 
• German Chemical Society 
• German Physical Society 

In a recent article published in "Nature", M. Bohman and the BASE collaboration  demonstrate the first sympathetic cooling of a single proton using a cryogenic two-Penning-trap system. To this end, the single proton was stored in the proton trap (PT) and a cloud of Be⁺ ions in a separate beryllium trap (BT). In contrast to the common endcap technique, the coupling was realized by connecting the two Penning traps to a superconducting cryogenic LC circuit with resonance frequency near their axial frequencies. This new cooling technique allows to reach proton temperatures far below the environment temperature. The lowest proton temperatures are not found by minimizing the Be⁺ temperature, but by maximizing the coupling of the Be+ ions to the LC resonator. In the demonstration measurement, the proton temperature was reduced by 85%, from 17 K environment temperature to 2,6 K.

The novel sympathetic laser-cooling technique will enable enhanced precision experiments of any charged species at lower temperatures. In particular, it can be readily applied to cool protons and antiprotons in the same large macroscopic traps that enable precision measurements of the charge-to-mass ratio and g-factor. This will allow for improved precision in matter-antimatter comparisons and dark matter searches, performed by the BASE collaboration.
Furthermore, the successful extension of laser cooling to particles in spatially separated traps may contribute to develop quantum control techniques for previously inaccessible particles such as highly charged ions, molecular ions, and antimatter particles.

Please read more in the "Nature" article  and the associated article in News & Views .

The innovative particle cooling technique of the BASE collaboration has been selected to be among the Physics World Top 10 Breakthroughs in 2021 .

Further information also in the press releases of the "Stored and Cooled Ions Division"  and the MPIK .

Our PostDoc Peter Micke was awarded the Wilhelm and Else Heraeus Young Physicists Award 2020.
The Faculty of Mathematics and Physics at Leibniz University Hannover has honored his outstanding dissertation in the field of quantum optics entitled "Quantum Logic Spectroscopy of Highly Charged Ions". The dissertation prize was established in 2019 by the Wilhelm and Else Heraeus Foundation and is endowed with 2.000 Euro.

We cordially congratulate Dr. Peter Micke on receiving this distinction of his scientific work.

Please read more in the News of Leibniz University Hannover   (in German).

Our center members Prof. Dr. Piet O. Schmidt (Physikalisch-Technische Bundesanstalt, PTB) and Dr. José R. Crespo López-Urrutia (Max Planck Institute for Nuclear Physics, MPIK) are coauthors of a recent article published in "Nature".
In the article, P. Micke, T. Leopold, S. A. King et al. report on pioneering optical measurements of highly charged ions with unprecedented precision. The measurements were carried out by isolating a single highly charged ⁴⁰Ar¹³⁺ ion from an extremely hot plasma and bringing it practically to rest inside a cryogenic linear Paul trap together with a laser-cooled, singly charged ⁹Be⁺ ion. This technique enabled the scientists to perform coherent, optical-clock-like laser spectroscopy of an electric-dipole-forbidden optical transition in an highly charged ion (HCI) using quantum logic, at a level of precision that is eight orders of magnitude higher than the previous state of the art.
The experiment proves the feasibility of hertz-level optical spectroscopy of HCIs and opens up this large class of atomic systems to the tools of cutting-edge frequency metrology and quantum information processing. The presented techniques are not limited to the proof-of-principle HCI, ⁴⁰Ar¹³⁺, but can be applied more generally to forbidden transitions in other HCIs. Furthermore, the demonstrated techniques are not limited to the optical domain and thus will enable novel high-accuracy atomic clocks based on HCIs and unrivalled tests of fundamental physics.

Please read more in the "Nature" article  and the press release of the MPIK  / PTB  (idw ).

In a recent article published in "Nature" our steering board member Dr. Christian Smorra, the BASE collaboration  and the Budker group  from the Helmholtz Institute Mainz report on the direct experimental search for interactions between antimatter and dark matter. The measurement was performed at the Antiproton Decelerator (AD)  of CERN, Geneva, utilizing a novel two-particle spectroscopy method in an advanced cryogenic multi-Penning trap system. The result reported in the present article searches for periodic changes of the antiproton spin precession frequency as signature for the axion-antiproton interaction. The measurements allowed setting considerable first constraints on the possible strength of the interaction between ultralight axion-like particles with antiprotons, which are five orders of magnitude more sensitive than astrophysical limits.

Please read more in the "Nature" article  and the news of the "Stored and Cooled Ions Division" .

Our scientific coordinator Dr. Andreas Mooser (MPIK, division of Klaus Blaum) and steering board member Dr. Christian Smorra (RIKEN and Johannes Gutenberg University Mainz) received the "IUPAP Young Scientist Prize in Atomic, Molecular and Optical Physics 2019".
Both young scientists received the prize "for their outstanding contributions to determine the most precise comparison of the proton-to-antiproton charge-to-mass ratios and the most precise comparison of the proton and antiproton magnetic moments, constituting two different world-record tests of the fundamental charge, parity, and time reversal symmetry in these systems".
The prize was granted on July 29, 2019 on the "XXXIst International Conference on Photonic, Electronic and Atomic Collisions (ICPEAC)" at Deauville, Normandy, France. It includes a certificate, a medal and an invited presentation at ICPEAC.

We cordially congratulate Dr. Andreas Mooser and Dr. Christian Smorra on receiving this distinction of their scientific work.

Please read more in the press releases of the MPIK  (in German) and the IUPAP .

On April 8, 2019, the inauguration of the Max Planck-RIKEN-PTB Center for Time, Constants and Fundamental Symmetries, took place at RIKEN, Tokyo, Japan.
For this event, a symposium was organized with invited speakers Marianna Safronova (Univ. Delaware) and Yoshiro Takahashi (Kyoto University), and center speakers Klaus Blaum (MPG), Ekkehard Peik (PTB), and Stefan Ulmer (RIKEN). Guests like Prof. M. Stratmann (President MPG), Prof. J. Ullrich (President PTB), Prof. S. Koyasu and Prof. M. Kotani (RIKEN Executive Directors), and Dr. H. von Werthern, the ambassador of Germany in Japan, joined the event.

Please read also the news of RIKEN , PTB  and BASE .

Information of the Max Planck Society on the new Max Planck-RIKEN-PTB Center:

• Interview with Klaus Blaum, co-director of the new Center (in German) 
• Three new Max Planck Center (in German) 

The Max Planck Institute for Nuclear Physics  (MPIK), the Max Planck Institute of Quantum Optics  (MPQ), the Physikalisch-Technische Bundesanstalt  (PTB) and Japan's largest comprehensive research institution RIKEN  have proposed a new research center to intensify their successful collaboration in the domain of "Time, Constants and Fundamental Symmetries".

The application of this Max Planck-RIKEN-PTB Center for Time, Constants and Fundamental Symmetries has been approved in October 2018 for five years. The new initiative started on January 1, 2019, the official opening ceremony will be on April 8, 2019 at RIKEN in Tokyo, Japan. The total financial budget will be about 1.5 M€ per year, shared equally between MPG, PTB and RIKEN. The research center will be operated by three Co-Directors: Klaus Blaum (MPG), Ekkehard Peik (PTB), and Stefan Ulmer (RIKEN).

The MPIK participates with two divisions in the "Center for Time, Constants and Fundamental Symmetries", our division on “Physics with Stored and Cooled Ions” leaded by Klaus Blaum and the division of Thomas Pfeifer on "Quantum Dynamics and Control".

The new Max Planck-RIKEN-PTB Center will provide a synergetic and close collaboration, especially on the students' level, between experimental groups in atomic physics, antimatter physics, nuclear physics, quantum optics and metrology to tackle fore-front topics in precision measurements of time and constants of nature, to test fundamental symmetries and contribute to ultra-high precision searches for physics beyond the Standard Model of particle physics.
The leaders of the Max Planck-RIKEN-PTB Center expect that the intensified collaboration will lead to the development of novel experimental techniques which will outperform the state-of-the-art of contemporary experiments.

Please read more in the press releases of the MPIK  (idw ), the MPQ , the PTB  and the CERN Courier .