Figure 1

Band structure for a $4E_{\mathrm{r}}$ deep lattice in the repeated-zone scheme. The dotted lines represent the free particle parabolae to which the bands adiabatically connect as $V\to 0$. The region in dark gray corresponds to the first Brillouin zone. The region in light gray corresponds to the second Brillouin zone.Reuse & Permissions

Figure 2

(Color) Dragging of atoms in a moving lattice followed by a sudden turn off of the lattice. (a) presents the time sequence. (b) shows the absorption image of the cloud after a $1.5\mathrm{ms}$ time of flight following a sudden turn off of the lattice for different lattice velocities $v$, related to the quasimomentum by $q=-Mv$. The numbers on the vertical axis refer to the atomic velocity in units of $v_{\mathrm{r}}$. The average velocity of the atoms in the laboratory frame, deduced from (b), is shown in (c) vs the velocity of the lattice. The initial velocity of the condensate in the magnetic trap fluctuates with an rms value of $0.03v_{\mathrm{r}}$. The mean velocity, after suddenly turning off the lattice, thus exhibits the same fluctuations. The solid curve is the mean velocity of the atoms calculated from the band structure for a $4E_{\mathrm{r}}$ deep lattice.Reuse & Permissions

Figure 3

(Color) Dragging of atoms in a moving lattice followed by an adiabatic turn off of the lattice. (a) presents the time sequence. (b) shows the absorption image of the cloud after a $1.5\mathrm{ms}$ time of flight following the adiabatic turn off of the lattice for different lattice velocities. The numbers on the vertical axis refer to the atomic velocity in units of $v_{\mathrm{r}}$.Reuse & Permissions

Figure 4

(Color) Acceleration of atoms in the ground state $(n=0)$ band starting from $q=0$. The lattice is adiabatically raised up to $13E_{\mathrm{r}}$, accelerated and then adiabatically turned off at constant velocity. (a) shows images of the condensate after time of flight for increasing final lattice velocities. (b) shows the position of the center of mass of the cloud in the laboratory frame. The circles are the positions measured in (a), whereas the crosses represent the position of the cloud minus the displacement due to the dragging of the lattice. It therefore gives the momentum of the atoms.Reuse & Permissions

Figure 5

(Color) Acceleration of the lattice with atoms initially loaded into the band $n=1$, starting from $q=1.5\hslash k$. The $13E_{\mathrm{r}}$ lattice is raised adiabatically, accelerated, and then turned off adiabatically. (a) shows the images of the cloud in the laboratory frame after a $1.2\mathrm{ms}$ time of flight for various final lattice velocities. (b) presents the momentum deduced from the positions of the cloud, after correction for the dragging.Reuse & Permissions

Figure 6

Same experiment as in Figs. 4, 5. Velocity of the atoms in the lattice frame after acceleration of the lattice for different final lattice velocities. The velocities are deduced from Figs. 4b, 5b by subtracting the velocity of the lattice. In (a) the atoms are prepared in the ground state band, whereas they are prepared in the first band for the results of (b). The plain lines are the theoretical group velocity calculated for a $0.1E_{\mathrm{r}}$ deep lattice.Reuse & Permissions

Figure 7

Dephasing of a condensate sitting in a $5E_{\mathrm{r}}$ deep lattice for a time $t$. The time-of-flight has the same $3\mathrm{ms}$ duration for all the images. The right column shows the density profiles of the images in the left column, integrated perpendicular to the axis of the lattice. In (a), no lattice was applied. In (b) the lattice was suddenly switched off. In (c) and (d) the cloud stays in the lattice for 0.5 and $9\mathrm{ms}$, respectively.Reuse & Permissions

Figure 8

Evolution of the rms value of the observed the quasimomentum distribution of the atoms as a function of the time spent by the atoms in the lattice. The dotted line represents the expected width when we convolve the distribution of Fig. 7a with a uniformly populated first Brillouin zone.Reuse & Permissions

Figure 9

Acceleration of a cloud of incoherent atoms in a $5E_{\mathrm{r}}$ deep lattice. The circles represent the momentum of the center of mass of the cloud, in the laboratory frame, after acceleration of the lattice. The adiabatic ramp down is followed by a $3\mathrm{ms}$ time of flight. The line represents the velocity of the lattice.Reuse & Permissions