Séminaires

Title of seminar: From Meyer and Mendeleev to Oganessian and Dirac: What next after the superheavies and is there an end in sight for the Periodic Table?

Abstract:

The first periodic table of elements was proposed by Dmitri Ivanovich Mendeleev in 1869. It was based on arranging the elements in ascending order of atomic weights and grouping for similarities in chemical properties. Mendeleev predicted the existence and properties of new elements and pointed to accepted atomic weights that were flawed. At this time, it was not known how far one can increase the atomic weight to the critical point where heavy elements become unstable and undergo radioactive decay or when electronic levels dive into the Dirac sea. A century later it was speculated that the periodic table would end with heavy atomic nuclei containing no more than 100 protons because of the immense Coulomb repulsion between the protons. In 1948, however, Goeppert-Mayer pointed out that the nuclear shell model can significantly increase the stability of the atomic nuclei, and Meldner demonstrated in 1967 that the next proton-neutron-shell closure (island of nuclear stability) will take place
at a nuclear charge of Z = 114 and a neutron number of N = 184. Over the past two decades, we gained detailed insight into the nuclear stability problem by producing new superheavy elements up to a nuclear charge of Z = 118 (oganesson). The periodic table is most fundamental to chemistry, but key questions remain unanswered: where does the periodic table end from a theoretical and practical point of view? Can we still do chemistry with exotic and highly unstable elements? How can one predict the chemical and physical behaviour of these superheavy elements as the electronic spectrum becomes dense? What is quantum theory doing in the super-critical Coulomb field region when electronic states dive? Do
superheavy elements exist in nature, and are these produced in supernova explosions or neutron star mergers?

Title of seminar: Observation of entanglement in a cold atom analog of cosmological preheating

Abstract:

Parametric resonance is a universal phenomenon that arises across all scales, from Faraday waves in a water container to particle creation in the early Universe. (Quasi)particles are created in pairs of opposite momenta, and their exponential growth is triggered by fluctuations, such as thermal noise. However, if the initial mean number of (quasi)-particles is zero, vacuum fluctuations initiate the growth, yielding an entangled state. In this seminar, I will report on the experimental parametric creation of opposite-momentum quasi-particles in a Bose-Einstein condensate, and on the evolution of their number and entanglement. This experimental observation is made possible by the introduction of a novel entanglement criterion, to relate number correlation function to entanglement.

There should furthermore be, tomorrow thursday, the next presentation in the series by Peter Schwerdtfeger. Let’s enjoy our summer science camp and come in force to both!

Title of seminar: Left or Right in Nature – The Origin of Biomolecular Homochirality

Abstract:

Emil Fischer’s studies of peptides and sugars led to chiral molecules (D-sugars and L-amino acids) and to the confirmation of Pasteur’s conjecture that the universe is disymmetric. It is well known that D-sugars and L-aminoacids completely dominate the biochemistry of living organisms. But what is the cause for this single handedness in nature? Is biomolecular homochirality a necessary condition for life? Biomolecular homochirality at the microscopic level is supposed to be responsible for most of the symmetry breaking effects at the macroscopic level, for example that our heart is on the left-hand side of our body. On the microscopic side, a fundamental discovery of the last century is that our Universe is intrinsically left-handed (Weinberg-Salam-Glashow theory), the electro-weak interaction (parity-odd) gives rise to primarily left-spinning electrons during beta decay. In 1957 Lee and Yang discovered parity violation in the K+ decay, which was confirmed shortly after by Wu et al. for the -decay. It is now well accepted that parity violation can lead to a small energy
difference between enantiomers of chiral molecules, although there is no experimental verification yet of this distinct symmetry breaking effect. Can this tiny effect be responsible for biomolecular homochirality in nature?

Title of seminar: Quantum Probes of Fundamental Physics with Ultracold Molecules

Abstract:

Some of the biggest mysteries in physics—such as why the universe is made mostly of matter—suggest that our current understanding, the Standard Model of particle physics, is incomplete. One way to explore these open questions is by searching for a very slight distortion in the shape of the electron. If the electron is not perfectly round, it would point to new laws of physics that lie beyond our existing theories.

To look for this tiny effect, we use ultracold molecules as quantum sensors. By cooling molecules to temperatures near absolute zero and trapping them with beams of light, we can observe their quantum behaviour with exceptional precision. These tabletop experiments allow us to explore fundamental physics at energy scales that rival those probed by the world’s largest particle accelerators.

Beyond their role in fundamental physics, ultracold molecules also offer a rich platform for quantum technologies. Their complex internal structure makes them useful for quantum computing, highly sensitive measurements, and even studying chemical reactions in entirely new quantum regimes. Together, these capabilities make ultracold molecules a powerful toolset for advancing both our understanding of nature and the technologies of the future.

Title of seminar: How to create a distributed entangled sensor network with tunable long-range interaction using a double-well superlattice?

Abstract:

In this work, we consider a system made of several double wells (DW) loaded with atoms that interact via dipolar interactions (as described in [1] for example). Performing a two-mode approximation for each DW, we can derive an effective spin-Hamiltonian that describes the interactions between the DWs and that can be tuned by playing on the geometry of the DW superlattice or adding light induced dipolar interactions [2]. This Hamiltonian leads to entanglement and squeezing between the DWs when we perform a quench experiment. We are able to determine numerically and analytically the amount of local and shared squeezing using multiparameter squeezing [3] for different sets of Hamiltonian parameters, and we estimate the metrological interest of our system. Finally, we propose two protocols to take advantage of this entangled sensor network in the case of only two DWs, one for enhanced gradiometry using ellipse fitting methods [4, 5], and the second one using quantum non demolition measurements to transfer the multiparameter squeezing delocalised on the whole system to a single DW [6].

References:
[1] L. Masi, T. Petrucciani, G. Ferioli, G. Semeghini, G. Modugno, M. Inguscio, and M. Fattori, Phys. Rev. Let. 127 020601 (2021)
[2] M. Maiwöger, M. Sonnleitner, T. Zhang, I. Mazets, M. Mallweger, D. Rätzel, F. Borselli, S. Erne, J. Schmiedmayer and P. Haslinger, Phys. Rev. X 12 031018 (2022)
[3] M. Gessner, A. Smerzi, and L. Pezzè, Nat. Com. 11 3817 (2020)
[4] R. Corgier, M. Malitesta, L. A. Sidorenkov, F. Pereira Dos Santos, G. Rosi, G. M. Tino, A. Smerzi, L. Salvi, and L. Pezzè, arxiv.2501.18256 (2025)
[5] T. Petrucciani, A. Santoni, C. Mazzinghi, D. Trypogeorgos, F. S. Cataliotti, M. Inguscio, G. Modugno, A. Smerzi, L. Pezzè, and M. Fattori, arXiv:2504.17391v1 (2025)
[6] L. Pezzè, A. Smerzi, M. K. Oberthaler, R. Schmied, and P. Treutlein, Rev. of Mod. Phys. 90 (2018)

Title of seminar: Floquet-Engineering of Feshbach Resonances and Bound States in the Continuum

Abstract:

His talk will be on the control of interaction properties, in ultracold atom systems, and how it enables the realization of unconventional bound states (also seen in different fields such as photonics ans acoustics)