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Optically induced lensing effect on a Bose-Einstein condensate expanding in a moving lattice
L Fallani1, F S Cataliotti, J Catani
1European Laboratory for Non-Linear Spectroscopy (LENS), INFM and Dipartimento di Fisica, Università di Firenze, via Nello Carrara 1, I-50019 Sesto Fiorentino (FI), Italy. fallani@lens.unifi.it
Physical Review Letters
|December 20, 2003
Summary
We observed a lensing effect on Bose-Einstein condensates in a moving optical lattice. Changing atom velocity focused the condensate, demonstrating a quasimomentum-dependent effective mass.
Area of Science:
- Quantum physics
- Atomic physics
- Condensed matter physics
Background:
- Bose-Einstein condensates (BECs) exhibit quantum phenomena.
- Optical lattices provide periodic potentials for ultracold atoms.
- Controlling BEC expansion in lattices is key to quantum simulations.
Purpose of the Study:
- To experimentally observe and characterize a lensing effect on a Bose-Einstein condensate.
- To investigate the role of effective mass and quasimomentum in BEC dynamics.
- To validate theoretical models with experimental results.
Main Methods:
- Expanding a Bose-Einstein condensate within a moving one-dimensional optical lattice.
- Modulating the atomic velocity relative to the lattice.
- Comparing experimental observations with numerical simulations of an effective 1D model.
- Performing band spectroscopy via real-space wave packet propagation.
Main Results:
- Observed a lensing effect on the expanding Bose-Einstein condensate.
- Demonstrated that the periodic potential leads to a quasimomentum-dependent effective mass.
- Induced condensate focusing by altering the atom-lattice velocity.
- Achieved agreement between experimental data and theoretical predictions.
Conclusions:
- The study confirms the lensing effect on BECs in moving optical lattices.
- Effective mass dependent on quasimomentum governs the observed focusing.
- The findings validate the 1D theoretical model and offer insights into quantum gas dynamics.