Research Article

Collective Modes of an Ultracold 6Li-40K Mixture in an Optical Lattice

Figure 3

The collective-mode dispersion (triangles) calculated by the Bethe-Salpeter formalism for a 2D system with , , , , , , and . The speed of sound to the direction of the -axis is . The squire points are calculated by secular determinant used in [13], and the corresponding speed of sound is .