  The spin wave excitations emerging from the chiral helically modulated
120$^{\circ}$ magnetic order in a langasite Ba$_3$NbFe$_3$Si$_2$O$_{14}$
enantiopure crystal were investigated by unpolarized and polarized inelastic
neutron scattering. A dynamical fingerprint of the chiral ground state is
obtained, singularized by (i) spectral weight asymmetries answerable to the
structural chirality and (ii) a full chirality of the spin correlations
observed over the whole energy spectrum. The intrinsic chiral nature of the
spin waves elementary excitations is shown in absence of macroscopic time
reversal symmetry breaking.
