This talk is focused on a transfer of information across a many-body system. It will be shown that a single qubit can play the role of an antenna that gathers vast amounts of information from a complex system. Moreover, single-particle measurements performed on this antenna can provide information about the speed of signal propagation in the system. This way, one can access the Lieb-Robinson bound without measuring the two-body correlations.

A condition will be formulated under which the antenna, far apart from the source and embedded in a many-body interacting medium, can still collect the complete information. A striking feature of this setup is that a single-qubit antenna can accommodate even the full signal amplified by the entanglement of the source. In consequence, the retrieval of this information can be performed with simple one-qubit operations on the antenna (which will be fully characterized) rather than multi-qubit measurements of the source.