Self-excited truncated motional squeezed state in a quasi-2D Bose–Einstein condensate

We demonstrate a self-excitation protocol to generate truncated motional squeezed states in a quasi-two-dimensional Bose–Einstein condensate using intrinsic atom–atom interactions. By abruptly relaxing the transverse trapping potential, interaction energy transforms into kinetic energy, exciting a coherent superposition of motional states. The induced dynamic is beyond conventional collective mode approximation. Limited kinetic energy produces a truncated motional squeezed state with a non-Gaussian density distribution suitable for quantum state engineering. Using single-shot in situ absorption imaging, we develop a variance-based quantum tomography method to reconstruct the quantum state. Our experiment realized a self-excited squeezed state with a squeezing parameter χ=0.66±0.05, which is expected to give −5.73±0.4 dB squeezing for full-state. However, truncation reduces the squeezing to −5.03±0.2 dB due to limited Fock states. Interaction-driven self-excitation combined with single shot variance-based tomography provides a versatile mechanism for generating and characterizing non-Gaussian squeezed states in precision quantum metrology.