Enhanced Electron-Electron Entanglement in Few-Cycle Laser-Atom Interactions

The rapid advancements of ultrafast intense laser technology have opened new avenues for investigating entanglement in laser-induced systems. However, the application of these advances in quantum technology requires a reliable and universally applicable method for enhancing and regulating entanglement. Here we demonstrate how a few-cycle intense laser field can significantly enhance the degree of entanglement compared to its multi-cycle counterpart, using the example of electron-electron entanglement of orbital angular momentum (OAM) states in recollision-excitation non-sequential double ionization of Ar atoms. By confining the ionization dynamics to a specific narrow time window, the few-cycle pulse purifies the electron trajectories, thereby ensuring high coherence between entangled OAM channels and enhancing entanglement. Furthermore, the degree of entanglement can be effciently modulated by varying the carrier envelope phase (CEP) of the few-cycle laser pulse, which is achieved by altering the population across OAM channels. Optimizing coherence through electron trajectory purification with a designed specific temporal waveform of laser field provides a general pathway for enhancing entanglement in laser-induced systems.