Interference of an Array of Independent Bose-Einstein Condensates

We have observed high-contrast matter wave interference between 30 Bose-Einstein condensates with uncorrelated phases. Interferences were observed after the independent condensates were released from a one-dimensional optical lattice and allowed to overlap. This phenomenon is explained with a simple theoretical model, which generalizes the analysis of the interference of two condensates.

Figure 1

Interference of Bose-Einstein condensates with uncorrelated phases. (a) A deep 1D optical lattice splits a cigar-shaped condensate into 30 independent BECs. (b) Absorption image of the cloud after 22 ms of expansion from the lattice. The density distribution shows clear interference fringes of high contrast. (c) Axial density profile of the cloud, radially averaged over the central $25\mu \mathrm{m}$. The fit described in the text gives a fringe amplitude $A_1=0.64$ for this image.

Figure 2

Polar plots of the fringe amplitudes and phases $(A_1,B_1)$ for 200 images obtained under the same experimental conditions. (a) Phase-uncorrelated condensates. (b) Phase-correlated condensates. Insets: Axial density profiles averaged over the 200 images.

Figure 3

Axial size of the cloud after 22 ms of expansion as a function of the lattice depth $V_0$. Inset: Zoom-in on the region where an unexplained heating of the cloud occurs. For all data points the lattice was raised in ${\tau }_{\mathrm{r}\mathrm{a}\mathrm{m}\mathrm{p}}=200\mathrm{m}\mathrm{s}$ and left on for ${\tau }_{\mathrm{h}\mathrm{o}\mathrm{l}\mathrm{d}}=500\mathrm{m}\mathrm{s}$ before TOF. Error bars are statistical. Outside the heating region, the slow increase of the axial size matches the expected dependence $Z_0\propto 1/\ell \propto V_0^{1/4}$.