  A previous publication [Europhysics Letters 78, 10009 (2007)] suggested to
coherently generate mesoscopic superpositions of a two-component Bose-Einstein
condensate in a double well under perfectly symmetric conditions. However,
already tiny asymmetries can destroy the entanglement properties of the ground
state. Nevertheless, even under more realistic conditions, the scheme is
demonstrated numerically to generate mesoscopic superpositions.
