Talk by Axel Stenquist

Title:

Entanglement Transfer and Control: In Photoionization from Strong Coupling to Spontaneous Decay

Abstract

In this theoretical work, we consider the ion-electron entanglement generated in photoionization in atoms, followed by strong coupling of the ion by ultrafast coherent Free-Electron-Laser-like pulses. Time-resolved von Neumann entropy is used to quantify the quantum correlation in the system. Using phase-locked pulse sequences, we show that both the buildup of the entanglement and its manifestation can be controlled, finding that the energy of the electron can be directly correlated with the internal states of the ion, which we refer to as amplitude entanglement. This allows for the entanglement to be detected through coincidence measurements. We propose a measure of this amplitude entanglement, which allows us to analyse the complex evolution of the wave packet in a simple way. The amplitude entanglement is found to follow the classical correlation in the ionic state and electron energy basis. After the interaction with the pulse, the ion spontaneously decays, transferring the entanglement from the ion-electron system to the multipartite ion-electron-photon system and finally to the electron-photon pair. The entanglement is found to be fragile to temporal decoherence, requiring attosecond phase stability of the pulse sequence, but robust to spatial decoherence.