02.09.2024Prof. Jan Plefka appointed to the Board of Trustees of the Volkswagen Foundation

Prof. Jan Plefka

Jan Plefka, Professor of Theoretical Physics (Quantum Field and String Theory) at the Department of Physics and member of IRIS Adlershof at HU Berlin, has been appointed to the Board of Trustees of the Volkswagen Foundation by the German Federal Government.

The Board of Trustees is the highest decision-making body of the Volkswagen Foundation. It consists of 14 personalities from science and society, half of whom are appointed by the Federal Government and half by the State Government of Lower Saxony. The tasks of the Board of Trustees include defining the funding guidelines, selecting the projects to be funded, monitoring the funded projects and advising the Board of Directors.

Professor Jan Plefka is a renowned theoretical physicist and professor at Humboldt-Universität zu Berlin. After studying physics and receiving his PhD from the University of Hannover in 1995, he was a postdoctoral researcher in New York, Amsterdam, and at the MPI Potsdam. He was a visiting professor at ETH Zurich and at CERN. His research is concerned with quantum field theory and its relation to gravity. Here, he made important contributions to questions of quantum gravity and string theory, in particular in the area of AdS/CFT correspondence and hidden symmetries in supersymmetric quantum field theories. More recently, he has developed together with his group an innovative quantum field theoretical formalism to answer questions in classical gravitational wave physics. The ERC Advanced Grant was awarded to him to fully unfold the potential of this quantum approach to classical physics. He is the spokesperson of the DFG Research Training Group 2575, "Rethinking Quantum Field Theory." Jan Plefka has received several awards, including a Feodor Lynen Fellowship from the Humboldt Foundation and the Lichtenberg Professorship from the Volkswagen Foundation.

IRIS Adlershof warmly congratulates its member Jan Plefka and wishes him every success in this new, responsible position.

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18.07.2024Prof. Nicola Pinna pioneered a novel technique for coating nano-particles and creates yolk-shell nanostructures.

Prof. Pinna, member of IRIS Adlershof,  and colleagues have revolutionized the Stöber method, originally for amorphous SiO2 colloids, by extending it to metal-organic frameworks (MOFs) and coordination polymers (CPs). Their innovative approach harnesses the slow, continuous diffusion of triethylamine (TEA) vapor to precisely control the deprotonation of organic ligands, paving the way for creating finely crafted amorphous CP spheres.


The synthesis of aMOFs and aCPs colloids and core-shell structures via mimicking the Stöber method.

Starting with a solution of metal ions and organic ligands, TEA vapor initiates the deprotonation process, allowing ligands to bond with metal ions and form intricate amorphous MOF or CP structures. Remarkably versatile, this method has successfully synthesized 24 distinct amorphous CP spheres using diverse metal ions and ligands. By introducing guest nanoparticles, they’ve achieved uniform core-shell colloids with conformal amorphous CP coatings.

But wait, there’s more! The method’s gradual deprotonation process enables the heterogeneous nucleation of amorphous MOFs on any substrate, regardless of its chemistry, structure, or morphology. This adaptability facilitated the synthesis of over 100 core-shell colloids, combining 20 different amorphous MOF or CP shells with more than 30 different core-nanoparticles.

And that’s not all! These core-amorphous MOF shell colloids can easily transform into diverse functional colloids using liquid-phase or solid-state processes.

Excitingly, these amorphous-based core-shell colloids hold immense potential as sacrificial templates for crafting multifunctional nanostructures. Yolk-shell architectures, featuring voids between the core and shell, are particularly promising for catalytic reactions, energy storage solutions, and advanced drug delivery systems.

These results are now published as:
Zhang, W., Liu, Y., Jeppesen, H.S., and Pinna, N.
Stöber method to amorphous metal-organic frameworks and coordination polymers.
Nat Commun 14, 5463 (2024).
DOI: 10.1038/s41467-024-49772-2
The article is open access.

19.06.2024Breakthrough in Gravitational Wave Physics:
Black Hole Scattering at Unprecedented Precision

Jan Plefka, member of IRIS Adlershof

Visualization of the scattering of two black holes including a wave profile

Visualization of the gravitational Bremsstrahlung from the scattering of two black holes (BSc thesis O. Babayemi)

In a groundbreaking achievement, an international team led by IRIS Adlershof member Jan Plefka has computed the dynamics of two black holes scattering off each other at the highest level of precision ever attained. Their work, published as an Editor's Choice in the prestigious journal Physical Review Letters, provides new insights into the powerful gravitational interactions between these extreme objects.

Black hole scattering is a fundamental problem in Einstein's theory of general relativity, with wide-ranging implications for astrophysics and gravitational wave astronomy. Understanding the gravitational interactions and radiation emitted when two black holes encounter each other is crucial for interpreting observations from gravitational wave detectors like LIGO and future third generation wave detectors scheduled to go nonline in the 2030s.

The new calculations, performed by researchers from Humboldt University Berlin, the Max Planck Institute for Gravitational Physics, and CERN, push the theoretical description of black hole scattering to unprecedented accuracy - the fifth post-Minkowskian order and next-to leading self-force order. This enormously challenging four-loop computation required state-of-the-art integration techniques and high-performance computing resources.

"Resolving this problem represents a new frontier in multi-loop calculations and effective field theory techniques," said group leader Jan Plefka. Co-author Benjamin Sauer commented "We had to optimize every aspect, from the integrand generation to developing new integration-by-parts methods." In total millions of 16 dimensional integrals had to be reduced to a basis of 470 master integrals, which were then computed.

Remarkably, the researchers found that at this new level of precision, the resulting scattering angle exhibits striking simplicity, without the appearance of new transcendental functions beyond polylogarithms of weight three. All theoretical checks, both internal and by matching to previous results, were passed successfully.

With this breakthrough, the researchers have laid the groundwork for incorporating their calculations into advanced gravitational waveform models for the next generation of gravitational wave detectors. The higher precision will enable exquisitely accurate tests of Einstein's theory and new insights into nuclear and fundamental physics from binary inspirals.

"Our results bring the prediction of gravitational waves from black hole encounters to unprecedented accuracy," said co-author Gustav Uhre Jakobsen. "This opens brilliant new avenues for extracting fundamental physics from gravitational wave observations in the future."

The research was funded by the Deutsche Forschungsgemeinschaft in the context of the Research Training Group 2575 “Rethinking Quantum Field Theory” and the European Research Council Advanced Grant “GraWFTy” of Jan Plefka.

Article:
Conservative Black Hole Scattering at Fifth Post-Minkowskian and First Self-Force Order
Mathias Driesse, Gustav Uhre Jakobsen, Gustav Mogull, Jan Plefka, Benjamin Sauer, and Johann Usovitsch
Phys. Rev. Lett. 132, 241402 – Published 13 June 2024
DOI: 10.1103/PhysRevLett.132.241402

Contact:
Prof. Dr. Jan Plefka
Sprecher Graduiertenkolleg 2575 „Rethinking Quantum Field Theory“
ERC Advanced Grant „GraWFTy"
Humboldt-Universität zu Berlin, IRIS Adlershof &
Institut für Physik, Arbeitsgruppe Quantenfeld- und Stringtheorie
Zum Großen Windkanal 2, D-12489 Berlin

Postal adress: Unter den Linden 6, 10099 Berlin, Germany

Email: jan.plefkahu-berlin.de
Tel:      +49 (0)30 2093 66409  
Sekr.:  +49 (0)30 2093 66413

qft.physik.hu-berlin.de
www2.hu-berlin.de/rtg2575/
X: @JanPlefka