Abstract

Due to interatomic collisions, the ground state of a Bose-Einstein condensate of dilute atoms is not, as is commonly assumed, a coherent state. First recognizing this point, Lewenstein and You¹ concluded that the condensate is actually an amplitude quadrature eigenstate. Including the effect of cubic and quartic fluctuation terms, Dunnmgham et al.² obtained the more physical description of a bent, amplitude-squeezed state with strong number squeezing. Theirs is a symmetry-broken model, with the condensate assumed to be in thermal equilibrium with another much larger condensate providing a reference phase. However, the model includes no description of this coupling and leaves open the question of whether the ground state is a pure state or a mixture.

© 1998 Optical Society of America