Contact

IRIS Adlershof
Humboldt-Universität zu Berlin
Zum Großen Windkanal 2
12489 Berlin
Germany

Director
Prof. Dr. Jürgen P. Rabe
rabeiris-adlershof.de


Management
officeiris-adlershof.de
phone:+49 30 2093-66350
fax:     +49 30 2093-2021-66350

 

NEWS

20.06.2024Dr. Gustav Mogull Receives the Karl Scheel Prize from the Physical Society of Berlin 2024

Dr. Mogull & Visualization of the scattering of two black holes including a wave profile

Dr. Gustav Mogull, a young researcher at the Department of Physics at Humboldt-Universität zu Berlin and associated with the Max Planck Institute for Gravitational Physics (Albert Einstein Institute), is receiving the prestigious Karl Scheel Prize for his groundbreaking work in the field of general relativity and gravitational wave physics.

Since the first observation of gravitational waves in 2015, a new field of research has emerged to study black holes, neutron stars, and test general relativity in extreme gravitational fields. Dr. Mogull has created a novel theoretical framework called the Worldline Quantum Field Theory (WQFT), developed in the research group of IRIS Adlershof-member Prof. Dr. Jan Plefka, to compute high-precision analytical predictions for the classical two-body problem in general relativity.

Using WQFT, Dr. Mogull has derived important physical observables for the dynamics of black holes and neutron stars in a series of papers published in prestigious journals such as Physical Review Letters. His results are already being applied in modeling gravitational wave signals for data analysis of current and planned future gravitational wave detectors.

The prize honors Dr. Mogull's outstanding theoretical work on the two-body problem, which is of great importance for future high-precision tests of general relativity and our understanding of gravitational waves. The crucial advance of WQFT lies in the transfer of methods from quantum field theory, which usually describes elementary particle physics, to the interaction of black holes. In this sense, one replaces the theoretical description of the scattering of protons in particle accelerators with the scattering of black holes in our universe. The Karl Scheel Prize, endowed with 5,000 euros, is awarded annually by the German Physical Society of Berlin for outstanding achievements in physics.

Gustav Mogull studied at the University of Cambridge and received his PhD in Edinburgh with work on scattering amplitudes in quantum field theory. After a postdoc in Uppsala (Sweden), he has been a long-term postdoc at the DFG Research Training Group "Rethinking Quantum Field Theory" (Speaker: Prof. Dr. J. Plefka) since 2020, which was recently extended for a second funding phase. The award-winning work was carried out within the framework of this research project, and Mr. Mogull is also actively involved in co-supervising doctoral and master’s thesis students in the program. He has recently received a fellowship from the Royal Society, which will lead him to a lectureship at Queen Mary University London starting in the fall of 2024.

Contact: Dr. Mogull and Prof. Dr. Plefka, Department of Physics, GRK 2575.

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
Mathematisch-Naturwissenschaftliche Fakultät
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

19.06.2024Enhanced surface-to-bulk Raman signal ratio using a transferable porous gold membrane

Enhanced surface-to-bulk Raman signal ratio using a transferable porous gold membrane

In a recent collaboration of the Emmy Noether Research Group "Physics of low-dimensional systems" around IRIS Adlershof member Dr. Sebastian Heeg at HU Berlin, researchers from the Leibniz-Institut für Kristallzüchtung (IKZ), the Université Le Mans, and the ETH Zurich, realized a novel modality in Raman spectroscopy through the development of surface-sensitive Raman scattering. This new approach addresses a major limitation of conventional Raman spectroscopy, where signals from surfaces or thin films are often weak and obscured by dominant bulk signals.

Surfaces play a pivotal role in science and industry as they are where most environmental interactions occur, including chemical reactions, adhesion, friction, and light interactions. Surface properties may differ significantly from bulk properties in terms of chemical composition, atomic arrangement, and electronic structure, influencing technological advancements such as catalysts and solar cells. Raman spectroscopy, a powerful, non-destructive technique for analysing molecular vibrations, provides insights into a material's chemical composition, crystallinity, defects, and strain. It is particularly valuable for characterising nanomaterials, thin films, and biological samples where precise surface information is essential.

The application of conventional Raman spectroscopy to surfaces and thin films has been constrained by dominant bulk signals. However, using transferable porous gold membranes (PAuMs) allows for the study of surface-specific Raman signals with unprecedented clarity. PAuMs contain irregular, slot-shaped nanopores that act as plasmonic antennas. When placing PAuM on a surface or thin film of interest, the nanopores amplify the Raman signal of the surface directly below while the membrane itself suppresses bulk signals. Combining these effects improves the surface-to-bulk Raman signal ratio by three orders of magnitude and enables truly surface-sensitive Raman scattering.

The researchers used graphene as a model surface, observing that the nanopores in the membranes enhance the graphene Raman signal a hundredfold. Placing a spacer between graphene and the PAuM reveals that the Raman enhancement is confined to the first 2 – 3 nm of the material below the membrane, which demonstrates true surface sensitivity. A first prototypal application regards quantifying the strain in a 12.5 nm thin Si quantum well layer using PAuMs. The layer is part of a Silicon-Germanium heterostructure designed to use spin qubits as a promising and fast-developing technology for quantum computing.

In a second use-case, PAuMs are used to study the surface of thin LaNiO3 film, a metallic perovskite used as an electrode material. The electrical conductivity of LaNiO3 films is strongly coupled to its crystallographic structure and can be tuned by the film thickness. With PAuM placed on top of LaNiO3, the authors observed a Raman mode splitting arising from the film’s surface and indicating a difference in the surface structure compared to the bulk. This finding is consistent with theoretical predictions and observations from scanning tunnelling microscopy studies.

“Our work connects two separate fields” says Heeg, “Conceptually, we extend the field of plasmon-enhanced Raman spectroscopy, which is almost exclusively used to study and sense molecular compounds and nanostructures, to the field of solid states materials like Silicon quantum wells, thin complex oxides films, and related surfaces.” The team is now exploring the potential of the method with partners in Berlin and international collaborators. Dr. Pietro Marabotti, Einstein International Postdoctoral Fellow in Heeg’s group and co-author of the study, remarks that “our approach is not limited to crystalline surfaces, which we use as a showcase, but may also be used to study, for example, biological surfaces or surface-bound chemical reactions.” Researchers interested in the method are invited to get in touch with the team.
 

Bulk-suppressed and surface-sensitive Raman scattering by transferable plasmonic membranes with irregular slot-shaped nanopores
Roman M. Wyss, Günther Kewes, Pietro Marabotti, Stefan M. Koepfli, Karl-Philipp Schlichting, Markus Parzefall, Eric Bonvin, Martin F. Sarott, Morgan Trassin, Maximilian Oezkent, Chen-Hsun Lu, Kevin-P. Gradwohl, Thomas Perrault, Lala Habibova, Giorgia Marcelli, Marcela Giraldo, Jan Vermant, Lukas Novotny, Martin Frimmer, Mads C. Weber, and Sebastian Heeg
Nat. Commun. 15, 5236 (2024).
DOI: 10.1038/s41467-024-49130-2 OPENACCESS

Kontakt:
Dr. Sebastian Heeg
Humboldt-Universität zu Berlin
IRIS Adlershof & Institut für Physik
Tel.: 030 2093-82295
E-Mail: sebastian.heegphysik.hu-berlin.de
Website: https://www.physik.hu-berlin.de/en/pld

05.06.2024DFG extends the Collaborative Research Centre FONDA

The CRC ‘FONDA - Foundations of Workflows for Large-Scale Scientific Data Analysis’ has been extended by the German Research Foundation (DFG) for a funding period of four years. IRIS Adlershof member Prof Dr Ulf Leser from the Department of Computer Science at Humboldt-Universität zu Berlin is the CRC's spokesperson.

The SFB FONDA is dedicated to researching methods for increasing productivity in the development, execution and maintenance of data analysis workflows (DAWs) for large scientific data sets. In today's research, ever larger amounts of data are being generated in all scientific disciplines. These need to be analysed using complex DAWs running on distributed and parallel computing infrastructures. Traditionally, these workflows are optimised for speed, which leads to individual solutions that are difficult to reproduce and use for other researchers.

The aim of FONDA is to develop methods and tools that significantly reduce the development time and costs of DAWs. This is to be achieved through new abstractions, models and algorithms that can form the basis for a new generation of workflow infrastructures. The CRC is investigating the following questions, among others: How can DAWs be developed that run equally efficiently on different software and hardware infrastructures? How must these workflows be designed so that they can adapt to changing input data or requirements? And how can reliable data analysis systems be built that recognise and control their own requirements in order to increase the reliability of their execution?

22.05.2024Joachim Sauer receives the 2024 Blaise Pascal Medal in Chemistry

The renowned chemist and founding member of IRIS Adlershof, Prof. Joachim Sauer, has been awarded the 2024 Blaise Pascal Medal in Chemistry by the European Academy of Sciences (EURASC) for his pioneering research in the field of catalytic reactions based on quantum chemistry. The EURASC honours his innovative research methods, such as hybrid quantum mechanical calculations and Grand Canonical Monte Carlo simulations, which have raised the understanding of heterogeneous catalysis to a new level. With the award of the medal, named after the French mathematician, physicist and philosopher Blaise Pascal, Prof Sauer joins a list of people who have made outstanding contributions to science, technology and research education. The award ceremony will take place on 29 and 30 October 2024 at the Academia das Ciências de Lisboa in Lisbon.

We congratulate our founding member on this honour.