Emulation of the dynamics of bound electron exposed to strong oscillatory laser field with Bose-Einstein Condensates

This paper employs a Bose-Einstein condensates to simulate the dynamical response of bound electrons in a strongly oscillating pulsed laser field. We investigate the excitation dynamics of Bose-Einstein condensates with repulsive interaction confined in a potential well with finite depth and width driven by a strong oscillatory pulse field. By numerically solving the Gross-Pitaevskii equation with Crank-Nicolson method and split operator method, we obtain the time-dependent wavefunction and therefore the evolution of density distribution in real space and that in momentum space, and the occupation distribution in energy space. It is shown that cold atoms with weak interaction oscillate as a whole body in a finite space when the amplitude of pulse drive is not strong enough. During the evolution atoms occupy the bound states with larger probability. Increasing the driving strength or atomic interactions promotes the excitation of atoms into continuum states and their diffusion out of the potential well, leading to complex structures or even interference-like patterns in the momentum distribution. The number of cycles in the pulse envelope plays a crucial role in the dynamical behavior: High-frequency driving can suppress diffusion and maintain localization. Furthermore, repulsive atomic interactions can enhance high-harmonic generation yields by several orders of magnitude. This study offers a new perspective for quantum simulations of ultrafast dynamics in strong fields and reveals the regulatory role of interactions in condensates on non-equilibrium dynamical processes.

💡 Research Summary

In this work the authors present a comprehensive quantum‑simulation study of the ultrafast dynamics of a bound electron exposed to a strong oscillatory laser field, using a Bose‑Einstein condensate (BEC) as an analog system. The BEC is initially confined in a finite‑depth Gaussian potential well, V_ext(x)=−V₀ exp(−x²/2r₀²), which mimics the bound‑state potential of an electron in an atom. A strong, time‑dependent electric field is then applied in the dipole approximation, modeled as V_drive(x,t)=x F sin²(ωt/2n_c) sin(ωt). The parameters F (field amplitude), n_c (number of carrier cycles in the pulse envelope), and g (effective 1‑D contact interaction strength) are varied systematically.

The dynamics of the condensate are governed by the one‑dimensional Gross‑Pitaevskii equation (GPE)
i∂_tψ =