We consider a mixture of a superfluid Fermi gas of ultracold atoms and a Bose-Einstein condensate of molecules possessing a continuous U(1) (relative phase) symmetry. We study the effects that a spatially random photo-associative-dissociative symmetr
y breaking coupling of the systems. Such coupling allows to control the relative phase between a superfluid order parameter of the Fermi system and the condensate wavefunction of molecules for temperatures below the BCS critical temperature. The presented mechanism of phase control belongs to the general class of disorder-induced order phenomena that rely on breaking of continuous symmetry.
We propose and analyze a general mechanism of disorder-induced order in two-component Bose-Einstein condensates, analogous to corresponding effects established for XY spin models. We show that a random Raman coupling induces a relative phase of pi/2
between two BECs and that the effect is robust. We demonstrate it in 1D, 2D and 3D at T=0 and present evidence that it persists at small T>0. Applications to phase control in ultracold spinor condensates are discussed.
