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Sergey Vasiliev (University of Turku)19/05/2026, 17:40Poster
We present experimental results on loading a large Ioffe-Pritchard trap with atomic hydrogen gas at temperatures around 100 mK. Dissociation of molecular hydrogen is performed in a cryogenic RF dissociator operating below 1 K. We demostrate that atomic fluxes close to atoms/s are obtained with the average RF power in the dissociator of several mW. We propose modifications of this source for...
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Andrzej Maroล (University of Warsaw)19/05/2026, 17:41Poster
Precision spectroscopy of simple atomic systems requires increasingly accurate theoretical predictions to match the growing precision of experimental measurements. In this work, a significantly improved theory of the muonic hydrogen hyperfine splitting (HFS) is presented in anticipation of upcoming high-precision measurements. The main achievement is the rigorous calculation of some finite...
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27. Updates towards a high precision Ortho-Positronium lifetime measurement with a PET-like detectorValentin Schmidt (ETH IPA)19/05/2026, 17:42Poster
Positronium, as a purely leptonic bound state, provides a unique laboratory for precision tests of bound-state QED. Among its measurable observables, the ortho-positronium decay rate plays a central role. Second-order corrections have been calculated, leading to a theoretical prediction at the 1 ppm level [1]. In contrast, the most precise experimental results remain two orders of magnitude...
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Wenting Gan (Innovation Academy for Precision Measurement Science and Technology, CAS)19/05/2026, 17:43Poster
Among nuclear isomers spanning keV to MeV energies, ^{229m}Th is exceptional: its excitation energy of 8.4 eV and radiative lifetime of ~10^3 s make it the lowest-known nuclear excited state. This unique system offers an intrinsic narrow transition with high insensitivity to external electromagnetic fields, establishing ^{229m}Th as the premier candidate for a nuclear optical clock. Such a...
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Ms Akiho Tanaka (Department of Applied Physics, School of Engineering, The University of Tokyo, Japan)19/05/2026, 17:44Poster
Positronium (Ps), the bound state of an electron and its antiparticle, the positron, is one of the simplest atomic systems suitable for rigorous tests of fundamental physics. Specifically, more precise experimental measurements and theoretical calculations of the 1Sโ2S interval of ortho-Ps hold the potential to discover indications of new physics beyond the Standard Model. Currently, a...
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Palki Gakkhar (Indian Institute of Technology Delhi)19/05/2026, 17:45Poster
Optical atomic clocks represent the state of the art in time and frequency metrology, achieving unprecedented levels of precision and stability by exploiting ultra-narrow optical transitions in atoms [1]. With demonstrated fractional uncertainties approaching the $10^{-18}$ level and beyond, optical clocks now surpass microwave standards and play an essential role in the redefinition of the SI...
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Florian Egli (Max-Planck-Institut fรผr Quantenoptik)19/05/2026, 17:46Poster
The precise measurement of the 1sโ2s transition in hydrogen serves as a cornerstone for testing quantum electrodynamics (QED) in simple atomic systems [1]. Extending such measurements to other hydrogen-like systems, such as He$^+$, probes higher-order QED corrections scaling with the atomic number $Z$ and reveals nuclear structure contributions beyond hydrogen. Despite its scientific interest,...
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Siegfried Werlen (ETH Zรผrich)19/05/2026, 17:47Poster
The LEMING experiment aims to measure the free fall of muonium (Mu) atoms to learn about the gravitational interaction of second generation leptonic antimatter. This measurement can only be carried out by a precise atomic beam interferometer. A novel Mu source based on superfluid helium allows us to produce a horizontal beam of the required quality. We are developing a prototype to demonstrate...
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Marcus Mรคhring (ETH Zรผrich)19/05/2026, 17:48Poster
Muonium, a purely leptonic system of an anti-muon and an electron, is a promising candidate to probe physics beyond the standard model and bound-state QED. The Mu-MASS collaboration has a broad spectroscopy program, including a rich microwave program, and long-term aims to measure the 1S-2S transition in the muonium atom to several orders of magnitude beyond the current state of the art....
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Viktoria Kraxberger (Austrian Academy of Sciences (AT))19/05/2026, 17:49Poster
Antiprotonโnucleus annihilation at rest is a complex process that is not yet fully described by existing models, particularly due to the scarcity of experimental data on production of heavy nuclear fragments, which has led to a limited understanding of final state interactions (FSI). New measurements are therefore essential to validate models of the annihilation dynamics and to clarify how the...
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Eugenio Fasci (1) Dipartimento di Matematica e Fisica, Universitร degli Studi della Campania โLuigi Vanvitelliโ, Caserta, Italy / Istituto Nazionale di Fisica Nucleare โ Sezione di Napoli, Napoli, Italy)19/05/2026, 17:50Poster
The ground-state hyperfine splitting in muonic hydrogen provides direct sensitivity to the proton Zemach radius, reflecting the combined effects of its spatial charge and magnetic moment distributions. Despite its fundamental importance, the hyperfine spin-flip transition has not yet been observed, owing to its extremely small excitation probability and the weak de-excitation energy underlying...
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Vincent Weis (Max Planck Institute of Quantum Optics)19/05/2026, 17:51Poster
Due to its simple structure, the Hydrogen atom is a powerful platform for precision tests of fundamental physics, more explicitly quantum electrodynamics (QED). The energy levels in atomic Hydrogen can be calculated up to a high degree of precision and can be written as:...
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รdรกm Nonn (MTAโELTE Lendรผlet โMomentumโ Molecular Quantum electro-Dynamics Research Group, Institute of Chemistry, Eรถtvรถs Lorรกnd University, Pรกzmรกny Pรฉter sรฉtรกny 1/A, Budapest, H-1117, Hungary)19/05/2026, 17:52Poster
The equal-time BetheโSalpeter (SalpeterโSucher) relativistic QED wave equation is used to describe two-spin-1/2-fermion systems, e.g., positronium-like systems or two-electron atoms and molecules. The equation containing only the instantaneous part of the interaction is the with-pair DiracโCoulomb(โBreit) equation (wpDC(B)), which includes the double-pair correction to the no-pair DC(B)...
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Evans Javary (ETH Zurich)19/05/2026, 17:53Poster
As purely leptonic atoms lacking internal structure, positronium constitutes an ideal system for high-precision tests of bound state quantum electrodynamics (QED) and search for new physics [1]. We report our results on the $\text{1}^\text{3}\text{S}_\text{1} \to \text{2}^\text{3}\text{S}_\text{1}$ interval in positronium, measured via two-photon optical spectroscopy using a continuous-wave...
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Surabhi Deshpande (Max Planck Institute of Quantum Optics)19/05/2026, 17:55Poster
The hydrogen atom has emerged as an ideal candidate for precision measurements of fundamental constants, since its energy levels can be calculated with high accuracy owing to its simple structure. Spectroscopy of two transitions of hydrogen provides a means to determine the precise values of the Rydberg constant $R_{\infty}$ and the proton charge radius $r_p$, and further comparison with other...
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Peter Hollosy (MTAโELTE Lendรผlet โMomentumโ Molecular Quantum electro-Dynamics Research Group, Institute of Chemistry, Eรถtvรถs Lorรกnd University, Pรกzmรกny Pรฉter sรฉtรกny 1/A, Budapest, H-1117, Hungary), Pรฉter Jeszenszki (MTAโELTE Lendรผlet โMomentumโ Molecular Quantum electro-Dynamics Research Group, Institute of Chemistry, Eรถtvรถs Lorรกnd University, Pรกzmรกny Pรฉter sรฉtรกny 1/A, Budapest, H-1117, Hungary)19/05/2026, 17:56Poster
This work collects the spin-dependent leading-order relativistic and quantum-electrodynamical corrections for the electronic structure of atoms and molecules within the non-relativistic quantum electrodynamics.$^1$ We report the computation of perturbative corrections using an explicitly correlated Gaussian basis set, which allows high-precision computations for few-electron systems. In...
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Elio Bera19/05/2026, 17:57Poster
This work is part of the international GRASIAN collaboration (https://grasian.ue). One goal of this collaboration is to demonstrate the existence of Gravitational Quantum States (GQSs) of Hydrogen atoms, using a cryogenic Hydrogen beam and an atomic mirror and absorber setup, located at Marietta Blau Institute. GQSs settle when particles are trapped in a triangular potential well made, on the...
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Tesse Tiemens (Vienna Center for Quantum Science and Technology, Atominstitut, TU Wien, Stadionallee 2, A-1020 Vienna, Austria)19/05/2026, 17:58Poster
In recent years, molecules have emerged as valuable precision metrology platforms for probing symmetry violations in fundamental physics. Heavy dipolar molecular species such as barium monofluoride (BaF) are particularly attractive, as their sensitivity to potential new physics is greatly enhanced, while remaining relatively simple to control due to their favorable molecular structure. Owing...
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Peter Hollosy (MTAโELTE Lendรผlet โMomentumโ Molecular Quantum electro-Dynamics Research Group, Institute of Chemistry, Eรถtvรถs Lorรกnd University, Pรกzmรกny Pรฉter sรฉtรกny 1/A, Budapest, H-1117, Hungary)19/05/2026, 17:59Poster
This work is concerned with two(many)-spin-1/2-fermion relativistic quantum mechanics and it is about the construction of one-particle projectors and potentially, one-particle propagators, necessary for quantum-electrodynamics (QED) corrections, using an inherently two(many)-particle, `explicitly correlated' basis representation, necessary for good numerical convergence of the results.
It...
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Caroline Rodenbeck (IAP-TLK)19/05/2026, 18:00Poster
From the observation of oscillations, neutrinos are known to have a mass.
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However, it remains an open question as to how large that mass is. One
way of determining the neutrino mass is the investigation of weak decay
kinematics. Especially suited is the beta decay of tritium, mainly due to its simple structure, high activity, and comparatively low endpoint value.
KATRIN, the Karlsruhe... -
Kees Steinebach (VU Amsterdam)19/05/2026, 18:01Poster
Precision measurements on calculable systems are widely used for tests of QED and probes for physics beyond the standard model. In our experiment we perform high precision spectroscopy on the $2\,^3S_1 โ 2\,^1S_0$ transition at 1557 nm in ultracold $^3$He and $^4$He.
On this transition we recently performed the most accurate frequency measurement (48 Hz) in helium, using a Bose-Einstein...
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Foivos Vouzinas (ETH Zurich)19/05/2026, 18:02Poster
$H_2^+$ is the simplest stable molecule, and its structure can be calculated ab initio with high precision using quantum electrodynamics. By comparing the calculations with experimental data, fundamental constants can be determined, and the validity of the theory itself can be tested. However, challenging properties such as high reactivity, low mass, and the absence of rovibrational dipole...
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