  This paper focuses on changing Fock matrix elements of two-mode squeezed
vacuum state (TMSVS) by employing three quantum operations in one-sided lossy
channel. These three quantum operations include one-photon replacement (OPR),
one-photon substraction (OPS) and one-photon addition (OPA). Indeed, three
conditional quantum states have been generated from the original TMSVS. Using
the characteristic function (CF) representation of quantum density operator, we
derive the analytical expressions of their Fock matrix elements, which are
dependent on the interaction parameters, including the squeezing parameter of
the input TMSVS, the loss factor and the transmissivity of the variable beam
splitter. For convenience of discussion, we only give the Fock matrices in the
subspace span {|00>,|01>,|10>,|02>,|11>,|20>} for these two-mode states.
Obviously, the TMSVS only has the populations in |00> and |11> in such
subspace. By comparing the generated states with the TMSVS, we find that: (1)
The generated state after OPR will remain the populations in |00> and |11>, and
add the populations in |10> and |20>; (2) The generated state after OPS will
lost the populations in |00> and |11>, but add the populations in |10> and
|20>; (3) The generated state after OPA will remain the population only in |11>
and add the population in |01>.
