  We explore excitation transport within a one-dimensional chain of atoms where
the atomic transition dipoles are coupled to the free radiation field. When the
atoms are separated by distances smaller or comparable to the wavelength of the
transition, the exchange of virtual photons leads to the transport of the
excitation through the lattice. Even though this is a strongly dissipative
system, we find that the transport is subradiant, that is, the excitation
lifetime is orders of magnitude longer than the one of an individual atom. In
particular, we show that a subspace of the spectrum is formed by subradiant
states with a linear dispersion relation, which allows for the dispersionless
transport of wave packets over long distances with virtually zero decay rate.
Moreover, the group velocity and direction of the transport can be controlled
via an external uniform magnetic field while preserving its subradiant
character. The simplicity and versatility of this system, together with the
robustness of subradiance against disorder, makes it relevant for a range of
applications such as lossless energy transport and long-time light storage.

Quantum Physics