  To each 2-dimensional irreducible p-adic representation of Gal(Qpbar/Qp)
which becomes crystalline over an abelian extension of Q_p, we associate a
Banach space B(V) endowed with a linear continuous unitary action of GL_2(Q_p).
When V is moreover phi-semi-simple, we use the (phi,Gamma)-module and the Wach
module associated to V to show that the representation B(V) is nonzero,
topologically irreducible and admissible.
