# Transient responses of double core-holes generation in all-attosecond pump-probe spectroscopy

## TL;DR

This paper explores how all-attosecond XFEL pump-probe spectroscopy can reveal the dynamics of double core-holes in neon, offering insights into electron correlations and coherence.

## Contribution

The study introduces a novel method using non-Hermitian dynamics simulations to analyze DCHs with attosecond precision.

## Key findings

- Population transfer to DCHs is observed through sequential irradiation by pump and probe lasers.
- Stark shifts and quantum path interference emerge at specific pulse intervals.
- Non-perturbation absorption/emission confirms the interchangeable role of pulses at higher intensities.

## Abstract

Double core-holes (DCHs) show remarkable and sensitive effects for understanding electron correlations and coherence. With advanced modulation of x-ray free-electron laser (XFEL) facility, we propose the forthcoming all-attosecond XFEL pump-probe spectroscopy can decipher the hidden photon-initiated dynamics of DCHs. The benchmark case of neon is investigated, and norm-nonconserving Monte-Carlo wavefunction method simulates non-Hermitian dynamics among vast states, which shows superiority in efficiency and reliability. In our scheme, population transfer to DCHs is sequentially irradiated by pump and probe laser. By varying time delay, Stark shifts and quantum path interference of resonant lines sensitively emerge at specific interval of two pulses. These ubiquitous multi-channel effects are also observed in phase-fluctuating pulses, derived from extra phases of impulsive Raman processes by pump laser. Non-perturbation absorption/emission verifies the uniquely interchangeable role of two pules in higher intensity. Our results reveal sensitive and robust responses on pulse parameters, which show potential capacity for XFEL attosecond pulse diagnosis and further attosecond-timescale chemical analysis.