Speaker
Description
We report on experiments with highly intense femtosecond laser pulses with tailored polarization to study entanglement of spatially separated atoms on femtosecond time scales.
Previously, it has been shown that circularly polarized light favors electrons with a certain magnetic quantum number in strong field ionization [1]. This preference was used to prepare and detect ring currents in single argon ions [2,3].
Building on these insights, we use a pump-probe scheme to prepare and detect ring currents in dissociating oxygen molecules. The laser pulses have intensities on the order of $10^{14}$ W/cm$^2$.
The pump pulse excites a ring current in molecular oxygen and simultaneously triggers the dissociation of the molecule into two spatially separated entangled oxygen atoms. The probe pulse allows us to investigate this pair of atoms on femtosecond time scales. We find that the valence electrons of the two atoms are entangled in their magnetic quantum number [5].
The momenta of the liberated electrons and the ions are measured in coincidence using cold-target recoil-ion momentum spectroscopy (COLTRIMS) reaction microscopes [4].
[1] I. Barth, O. Smirnova, Phys. Rev. A 84, 063415, (2012)
[2] T. Herath et al., Phys. Rev. Lett. 109, 043004, (2012)
[3] S. Eckart et al., Nat. Phys. 14, 701, (2018)
[4] J. Ullrich et al., Rep. Prog. Phys. 66, 1463, (2003)
[5] S. Eckart et al., Science Advances 9, eabq8227, (2023)
