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

Figure 2

The collective-mode dispersion of mixture in 2D optical lattice along the positive and negative directions. The filling factors are and . The interaction strength and the temperature are and , respectively. The secular determinant provides the speed of sound to the positive direction , while the speeds of sound to the negative direction is .