AWhat changed
Ben Dahan and colleagues prepared ultracold cesium atoms in the lowest band of a standing-wave optical potential and applied an inertial force by accelerating the lattice. After different evolution times they switched off the potential and measured atomic momentum distributions. The distributions recurred with the predicted Bloch period, while their inferred mean velocities yielded positive and negative band effective masses at different quasimomenta.
Scientific scope
Ben Dahan and colleagues prepared ultracold cesium atoms in the lowest band of a standing-wave optical potential and applied an inertial force by accelerating the lattice. After different evolution times they switched off the potential and measured atomic momentum distributions. The distributions recurred with the predicted Bloch period, while their inferred mean velocities yielded positive and negative band effective masses at different quasimomenta. This experiment observes an ensemble of atoms in an engineered optical lattice, not individual electron trajectories or a new Bloch theory. A sufficiently weak acceleration and adiabatic loading limit transfers to higher bands; the observed momentum distributions and effective masses depend on the experimental preparation, force, readout and band model. The inferred position amplitude is not a direct position measurement. The experiment is distinct from the earlier semiconductor optical-signal measurements and from later atomic-recoil fine-structure determinations.
Evidence
The linked original works support the scoped statement and contribution attribution. WRS has not independently replayed experiments or reconstructed a full mathematical proof. This experiment observes an ensemble of atoms in an engineered optical lattice, not individual electron trajectories or a new Bloch theory. A sufficiently weak acceleration and adiabatic loading limit transfers to higher bands; the observed momentum distributions and effective masses depend on the experimental preparation, force, readout and band model. The inferred position amplitude is not a direct position measurement. The experiment is distinct from the earlier semiconductor optical-signal measurements and from later atomic-recoil fine-structure determinations.
Contributors
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