Public Thesis Defense of Eduardo MARIN BUJEDO

Preparation and study of calcium rydberg atoms at ultracold temperatures: toward rydberg atom laser cooling by Eduardo Marin Bujedo -

Mardi 6 octobre 2026 à 16h00 - Auditoire CYCL01 - Bâtiment de Hemptinne - Chemin du Cyclotron, 2 - 1348 Louvain-la-Neuve -

Rydberg atoms serve as an instrumental platform for a number of
scientific and technological applications, including their use in high-resolution spectroscopy, metrological electric field sensing, ultracold
chemistry, or quantum information processing.
Nevertheless, for all these applications, the atoms must be cooled
down while in their ground state, prior to Rydberg excitation. The lack
of a direct active cooling mechanism limits the operation time, and thus their performance. This thesis presents theoretical and experimental contributions to the development of a calcium ultracold platform, laying the groundwork toward the study of the direct laser cooling of Rydberg atoms in future research lines.
Theoretically, this work investigates autoionization, the current bottleneck preventing the laser cooling of Rydberg atoms, and addresses
whether this decay process can be effectively suppressed. The autoionization rates were systematically calculated for core-excited Rydberg states of Mg, Ca, and Sr, in the range 20 ≤ n ≤ 65, revealing a strong dependence of them on the orbital quantum number, ℓ. The analysis of these results provided the justification for selecting calcium as the optimal candidate for experimental implementation.
Experimentally, a complete apparatus dedicated to ultracold Rydberg
physics was designed, built, and benchmarked against state-of-the-art
implementations. The setup comprises an atomic oven reaching
∼ 500 ºC; a passive Zeeman slower based on permanent magnets to
reduce the velocity of the atoms from ∼ 650 m/s to ∼ 35 m/s; a
calcium magneto-optical trap (MOT) that cools the ground-state Ca
atoms to T ∼ 1 mK and confines them for an average time τ = 16 ms;
and an electrode-stack for the ionization and detection of the Rydberg
atoms. High-resolution spectroscopy of the ultracold Ca Rydberg atoms with 30 ≤ n ≤ 80 was performed to characterize their radiative lifetimes and quadratic polarizabilities.

Jury members :

Prof. Matthieu Génévriez (UCLouvain) (Supervisor)
Prof. Xavier Urbain (UCLouvain) (Supervisor)
Prof. Arnaud Delcorte (UCLouvain) (Chairperson)
Prof. Clément Lauzin (UCLouvain) (Secretary)
Prof. Thierry Bastin (ULiège)
Dr. Patrick Cheinet (Université Paris-Saclay)

Pay attention : the public defense of Eduardo Marin Bujedo will also take place in the form of a videoconference