Seminarium KMMF "Teoria Dwoistości"

This talk is focused on a transfer of information across a many-bodysystem. It will be shown that a single qubit can play the role of anantenna that gathers vast amounts of information from a complex system.Moreover, single-particle measurements performed on this antenna canprovide information about the speed of signal propagation in the system.This way, one can access the Lieb-Robinson bound without measuring thetwo-body correlations.A condition will be formulated under which the antenna, far apart fromthe source and embedded in a many-body interacting medium, can stillcollect the complete information. A striking feature of this setup isthat a single-qubit antenna can accommodate even the full signalamplified by the entanglement of the source. In consequence, theretrieval of this information can be performed with simple one-qubitoperations on the antenna (which will be fully characterized) ratherthan multi-qubit measurements of the source.