Theoretical Interpretation of Strong‑Field Stabilization in Shaken Bose-Einstein Condensates

We present a theoretical study of strong‑field stabilization in shaken Bose–Einstein condensates confined in a focused Gaussian‑beam optical trap, in the low‑frequency regime where the drive frequency is comparable to the trap’s harmonic confinement. Time‑dependent Gross–Pitaevskii simulations reproduce key experimental observations and reveal distinct dynamical regimes as the shaking amplitude α₀ is increased to values nearly an order of magnitude larger than the Gaussian beam waist w₀, which sets the characteristic spatial scale of the trap.

For small amplitudes, the condensate follows the instantaneous trapping potential, and atom loss occurs primarily at the instantaneous peaks of the shaking field, analogous to strong‑field ionization. As α₀ increases, the loss rate rises monotonically until shortly after α₀ exceeds w₀/2, where it saturates and then decreases sharply, indicating strong‑field stabilization. At these large amplitudes, the condensate begins to follow the cycle‑averaged trap; near β = α₀ / w₀ ≈ 8/9, the averaged potential bifurcates into a double well, and the density reorganizes accordingly.