  Starting from the Quantum-Phase-Estimate (QPE) algorithm, a method is
proposed to construct entangled states that describe correlated many-body
systems on quantum computers. Using operators for which the discrete set of
eigenvalues is known, the QPE approach is followed by measurements that serve
as projectors on the entangled states. These states can then be used as inputs
for further quantum or hybrid quantum-classical processing. When the operator
is associated to a symmetry of the Hamiltonian, the approach can be seen as a
quantum--computer formulation of symmetry breaking followed by symmetry
restoration. The method proposed in this work, called Discrete Spectra Assisted
(DSA), is applied to superfluid systems. By using the blocking technique
adapted to qubits, the full spectra of a pairing Hamiltonian is obtained.
