  Out-of-time-ordered correlators (OTOC) are a quantifier of quantum
information scrambling and quantum chaos. We propose an efficient quantum
algorithm to measure OTOCs that provides an exponential speed-up over the best
known classical algorithm provided the OTOC operator to be estimated admits an
efficient gate decomposition. We also discuss a scheme to obtain information
about the eigenvalue spectrum and the spectral density of OTOCs.
