Nonlinear self-trapping of matter waves in periodic potentials

Area of Science:

• Atomic Physics
• Quantum Mechanics
• Condensed Matter Physics

Background:

• Bose-condensed atoms in optical potentials exhibit quantum phenomena.
• Nonlinear dynamics in Bose-Einstein condensates are crucial for understanding quantum systems.
• Self-trapping is a predicted phenomenon in nonlinear atomic systems.

Purpose of the Study:

• To experimentally observe and confirm nonlinear self-trapping of Bose-condensed atoms.
• To investigate the transition from diffusive expansion to self-trapping by varying nonlinearity.
• To compare experimental data with theoretical models.

Main Methods:

• Utilized Bose-condensed Rubidium-87 atoms in a one-dimensional waveguide.
• Superimposed a deep periodic potential onto the waveguide.
• Directly imaged atomic spatial distribution to observe trapping effects.
• Varied the nonlinearity of the system to study different regimes.

Main Results:

• First experimental observation of nonlinear self-trapping in Bose-condensed 87Rb atoms.
• Demonstrated a transition from diffusive expansion to a finite-width self-trapping regime with increased nonlinearity.
• Experimental data quantitatively matched solutions of the discrete nonlinear equation.

Conclusions:

• Nonlinear self-trapping in this system is a local effect.
• The observed phenomenon is analogous to predicted macroscopic self-trapping in double-well systems.
• Provides experimental validation for theoretical models of nonlinear atom dynamics.