An Atom Laser is not monochromatic

We study both numerically and analytically the possibility of using an adiabatic passage control method to construct a Mach-Zehnder interferometer (MZI) for Bose-Einstein condensates (BECs) in the time domain, in exact one-to-one correspondence with the traditional optical MZI that involves two beam splitters and two mirrors. The interference fringes one obtains from such a minimum-disturbance set up clearly demonstrates that, fundamentally, an atom laser is not monochromatic due to interatomic interactions. We also consider how the amount of entanglement in the system correlates to the interference fringes.