Quantum entanglement during single-cycle nonsequential ionization

TL;DR

This study investigates the ultrafast entanglement dynamics of two electrons in helium during nonsequential ionization driven by a single-cycle laser pulse, revealing how the carrier-envelope phase influences entanglement strength.

Contribution

It introduces a method to resolve electron entanglement on a sub-cycle timescale and demonstrates control of entanglement via laser phase tuning, a novel insight into electron correlation mechanisms.

Findings

Entanglement varies with carrier-envelope phase (CEP) tuning.

Up to 20% enhancement in peak entanglement achieved by CEP control.

Established links between entanglement, probability current, and electron momentum correlation.

Abstract

In order to elucidate the correlated motion of atomic electrons, we investigate the attosecond-scale dynamics of their entanglement arising due to nonsequential ionization driven by a strong, linearly-polarized laser field. The calculation is based on numerical integration of the time-dependent Schr\"{o}dinger equation for helium irradiated by a one-cycle, near-infrared field whose intensity is in the neighborhood of $1\textrm{ PW/cm}^2$. The entanglement measure (Schmidt weight) is resolved on a sub-cycle timescale, and its key dependency on the field profile is exposed for the first time by tuning the carrier-envelope phase (CEP) to control the ionization-recollision timing. We find that between CEP cases, this can result in a $20\%$ enhancement in the peak entanglement. A connection is made between the entanglement, the probability current, and the correlation coefficient for the two electron momenta, providing new insights into the nonsequential ionization mechanism.