Speaker
Description
In most atomic systems, single ionisation- channel continua are the exception, rather than the norm. When multiple ionisation channels are open, the purity of the state density operator can provide information on the electron–Parent Ion (PI) entanglement. Although this informa- tion may not be extracted using only an XUV pump, it can be obtained with the addition of a probe pulse. This is the principle behind pump- probe methods, which allow the for extraction of time-dependent information through varying the pump-probe delay.
One recently developed interferometric pump-probe method aimed at reconstructing the one-photon density operator is known as KvanttillståndstomogRafi av AttoseKundsElektroNvågpaket (KRAKEN). KRAKEN combines an XUV pump with a two-colour IR probe, allowing for interference measurements of the population at any two intermediate energies.
From the point of view of theory, both the one- and two-photon matrix elements can be di- rectly obtained, without the need for any of the assumptions relied on in the KRAKEN protocol. Thus, both the one-photon density matrix and its KRAKEN reconstruction may be calculated — and compared — directly. The present work makes use of Relativistic Random Phase-Approximation with Exchange (RRPAE) to simulate KRAKEN in argon, where the fine-structure splitting of the ground state results in separate ionisation channels. Both the and its KRAKEN reconstruction are calculated and compared to evaluate the assumptions present in the method.
