arXiv subjects

J. Szczepkowski

Publications and source records attributed to J. Szczepkowski.

3 recordsLinked to original sources

arXiv2025

The double minimum E(3)$^1Σ^{+}_{\mathrm{u}}$ state in Cs$_2$

The double minimum E$^1Σ^{+}_{\mathrm{u}}$ state in caesium dimer was investigated by analysing spectra of the E$^1Σ^{+}_{\mathrm{u}}$ $\leftarrow$ X$^1Σ^{+}_{\mathrm{g}}$ band system, simplified by polarisation labelling. A total of 6727 rotationally resolved transitions to levels situated in the inner well and above the internal barrier were identified and a potential energy curve allowing to reproduce their energies was constructed using the Fourier grid Hamiltonian and inverted perturbation approach methods. The unambiguousness of the potential curve in view of lack of data related to levels located in the outer well is discussed.

physics.atom-ph↗

arXiv2008

Analysis and calibration of absorptive images of Bose-Einstein condensate at non-zero temperatures

We describe the method allowing quantitative interpretation of absorptive images of mixtures of BEC and thermal atoms which reduces possible systematic errors associated with evaluation of the contribution of each fraction. By using known temperature dependence of the BEC fraction, the analysis allows precise calibration of the fitting results. The developed method is verified in two different measurements and compares well with theoretical calculations and with measurements performed by another group.

cond-mat.other↗

arXiv2008

Free-fall expansion of finite-temperature Bose-Einstein condensed gas in the non Thomas-Fermi regime

We report on our study of the free-fall expansion of a finite-temperature Bose-Einstein condensed cloud of 87Rb. The experiments are performed with a variable total number of atoms while keeping constant the number of atoms in the condensate. The results provide evidence that the BEC dynamics depends on the interaction with thermal fraction. In particular, they provide experimental evidence that thermal cloud compresses the condensate.

cond-mat.other↗