  Ground-state properties of a few attractively interacting ultra-cold atoms of
different mass confined in a one-dimensional harmonic trap are studied in terms
of the correlation noise. Depending on the mass ratio between the components'
atoms, the inter-particle correlations change their properties significantly
from a strong pair-like correlation to an almost uncorrelated phase. This
change is accompanied by the undergoing change in the structure of the
many-body ground state. A crucial role of the quantum statistics is emphasized
by comparing properties of the Fermi-Fermi mixture with a corresponding
Fermi-Bose system.
