  While the size of functional elements in memristors becomes of the orders of
nano-meters or even smaller, the quantum effects in their dynamics can
significantly influence their transport properties, consistent with recent
experimental observations of conductance quantisation in memristors. This
requires the development of experimentally realizable procedures to detect
quantumness of memristors. Here we developed an experimental protocol allowing
us to find evidence that the memristor can be in a superposition of states with
different memristivities. We simulate the nonlinearity induced in the quantum
memristive system via periodic projective measurements, observing how it
manifests itself in the emergence of additional spectral components in the
response to the harmonic signal. Moreover, the response demonstrates a resonant
behaviour when the frequency of the projective measurements commensurates with
the frequency of the input. We demonstrate that observation of such harmonic
mixing can be used as experimental evidence of quantum effects in memristors.
