Figure 3: Veselago lensing in one dimension.
From: Veselago lensing with ultracold atoms in an optical lattice
(a) Schematic of the relevant part of the atomic dispersion for a vanishing splitting between first (red) and second (blue) excited Bloch bands with the corresponding group velocities indicated. (b) Temporal sequence of absorption images for the case of such an ultrarelativistic dispersion in the lattice. After 1.3 ms a π-pulse is applied, leading to a refocusing. The false-colour images give the optical column density of atoms in the mF=−1 spin projection, as detected by a combination of a short microwave pulse transferring the population to the upper (F=2) hyperfine ground state and then applying a standard absorption imaging technique. The used temporal bin widths in the left panel is 100 μs, and the white lines are calculated trajectories for kx={±0.05,±0.1,±0.2}κ respectively. (c) Variation of the atomic cloud width versus time. (d,e) Corresponding data for a nonvanishing splitting between the Bloch bands, which leads to less perfect refocusing. For the data shown in the left panel, ΔE=0.28 Er. The shown error bars are given by the standard deviation of the mean, as determined by Gaussian fits to the atomic density distribution for three corresponding data sets.
