  Almost-dispersionless pulse transfer between the extremal masses of a uniform
harmonic spring-mass chain of arbitrary length can be induced by suitably
modifying two masses and their spring's elastic constant at both extrema of the
chain. It is shown that a deviation (or a pulse) imposed to the first mass
gives rise to a wave packet that, after a time of the order of the chain
length, almost perfectly reproduces the same deviation (pulse) at the opposite
end, with an amplitude loss that is as small as 1.3 % in the infinite-length
limit; such a dynamics can continue back and forth again for several times
before dispersion cleared the effect. The underlying coherence mechanism is
that the initial condition excites a bunch of normal modes with almost equal
frequency spacing. This constitutes a possible mechanism for efficient energy
transfer, e.g., in nanofabricated structures.

Classical Physics;Materials Science;Pattern Formation and Solitons