Suppression of hole decoherence in ultrafast photoionization

Abstract

In simple one-photon ionization, decoherence occurs due to entanglement between ion and photoelectron. Therefore, the preparation of coherent superpositions of electronic eigenstates of the hole in the photoion is extremely difficult. We demonstrate for the xenon atom that the degree of electronic coherence of the photoion in attosecond photoionization can be enhanced if the influence of many-body interactions is properly controlled. A mechanism at low photon energies involving multiphoton ionization is found, suppressing the loss of coherence through ionization into the same photoelectron partial waves. The degree of coherence found between the 4d 0 and 5s hole states is, on the one hand, limited by Auger decay of the 4d 0 hole. On the other hand, increasing the population ratio such that a significant portion of the state is in a true superposition of both states renders the maximization of the degree of coherence difficult.

Ion-photoelectron entanglement in photoionization with chirped laser pulses

“…We may expect quantum entanglement to be very common in attosecond science, since situations abound where photoionization leads to different combinations of cationic internal (electronic, vibrational, rotational) states and their accompanying photoelectron momentum states. Accordingly, several contributions have appeared in the literature pointing to the possible role of quantum entanglement in attosecond pump-probe experiments [13][14][15][16], and we have recently, following a prediction in [17], reported experiments where the degree of vibrational coherence in H 2 + ions formed by photoionization by a sequence of two attosecond XUV pulses (or two attosecond pulse trains) could be controlled by the delay between these two pulses [19].…”

“…Recently, the possible role that quantum entanglement can play in attosecond science, or-more generally-experiments involving photoionization [12], has started drawing increasing attention [13][14][15][16][17]. Attosecond pulses formed by highharmonic generation necessarily have photon energies in the extreme-ultraviolet (XUV) or soft x-ray spectral region [18], and hence are ionizing radiation for any sample.…”