Single top-quark production cross section at the LHC in ATLAS

Measurements of the single top-quark production cross-sections with the ATLAS detector in $pp$ collisions at the Large Hadron Collider (LHC) are presented. Results of measurements and searches for single top-quark production in the $t$-, $Wt$- and $s$-channel, as well as the determination of the CKM matrix element $\left|V_{tb}\right|$ are shown. Further, the separate measurement of the top- and antitop-quark $t$-channel production cross-section and the ratio of the two are presented, and several searches for exotic processes in single top-quark production are discussed. The latter include results from searches for flavour changing neutral currents, extra heavy charged gauge bosons ($W^\prime$), exited quarks, and searches for anomalous CP-violating couplings in the $Wtb$ vertex.