In August 2003 my two brothers and I (Servaas Kokkelmans) started our pelgrimage to Santiago de Compostella. Here are some pictures.

First part: Le Puy en Velay to Nasbinals.

Second part: Nasbinals to Cahors.

Third part: Cahors to Eauze.

Fourth part: Eauze to St Jean Pied de Port

Fifth part: St Jean Pied de Port to Logrono

Sixth part: Logrono to Fromista


Latest News:

Trapped electrons in the quantum degenerate regime

A full strength Coulomb interaction between trapped electrons can be felt only in absence of a neutralizing background. In order to study quantum degenerate electrons without such a background, an external trap is needed to compensate for the strong electronic repulsion. As a basic model for such a system, we study a trapped electron pair in a harmonic trap with an explicit inclusion of its Coulomb interaction. We find the eigenenergies of the system for any value of the trapping strength. The problem is solved either numerically or by using approximate methods. As function of the trapping strength a crossover can be made from the strongly to the weakly-coupled regime, and we show that in both regimes perturbative methods based on a pair-wise electron description would be effective for a many-particle trapped electron system.   arXiv:1508.00365

Stability of triplet rubidium ground-state molecules

Experiments involving ultracold molecules require sufficiently long lifetimes, which can be very short for excited rovibrational states in the molecular potentials. For alkali atoms such as rubidium, molecular, rovibrational ground-states can both be found in the electronic singlet and triplet configurations. The molecular singlet ground state is absolutely stable, however, the triplet ground state can decay to a deeper bound singlet molecule due to a radiative decay mechanism that involves the interatomic spin-orbit interaction. We investigate this mechanism, and find the lifetime of rubidium molecules in the triplet rovibrational ground-state to be about 13 minutes. This is sufficiently long for experimental purposes.   arXiv:1412.5799