  The concept of non-Markovianity (NM) in quantum dynamics is still an open
debate. Understanding how to generate and measure NM in specific models may aid
in this quest. In quantum optics, an engineered electromagnetic environment
coupled to a single atom can induce NM. The most common scenario of structured
electromagnetic environment is an optical cavity, composed by a pair of
mirrors. Here, we show how to generate and measure NM on a two-level system
coupled to a one-dimensional waveguide with no mirrors required. The origin of
the non-Markovian behavior lies in the initial state of the field, prepared as
a single-photon packet. We analyze how NM depends on two experimentally
controllable parameters, namely, the linewidth of the packet and its central
frequency. We relate the presence of NM to a $\pi$-phase shift between incoming
and emitted fields. We also show how the two output channels of the waveguide
provide distinct signatures of NM, both experimentally accessible.
