光晶格中非相干超冷原子的密度关联效应

Density correlation effect of incoherent ultracold atoms in an optical lattice

陷俘于光晶格中的Mott绝缘体态原子是非相干物质波波源.这种物质波从光晶格释放后不会出现一阶干涉现象,但是存在二阶干涉(密度关联)效应.针对这一现象,理论上给出了自由膨胀超冷原子气体的密度关联函数,该函数表现出清晰的干涉峰,其条纹结构与光栅衍射谱类似.进一步研究表明,密度关联函数的峰值结构与两探测器的相对位置有关,出现了物质波的"亚波长干涉"现象.

Atoms in the Mott insulator state trapped in an optical lattice are incoherence matter wave source.It is not the first-order,but the second-order interference effect （density correlation） that will appear for this incoherence wave source after being released.A density correlation function of the freely expanding ultracold gases is obtained theoretically,which presents sharp peaks of interference,and the stripes structure is similar to the diffraction gratings.It is further pointed out that the peak structure of the density correlation function depends on the relative position between two detectors.The phenomenon of subwavelength interference of matter waves is also proposed in this paper.