  In this work, we describe examples for calculating the 1-D circular
convolution of signals represented by 3-qubit superpositions. The case is
considered, when the discrete Fourier transform of one of the signals is known
and calculated in advance and only the QFT of another signal is calculated. The
frequency characteristics of many linear time-invariant systems and filters are
well known. Therefore, the considered method of convolution can be used for
these systems in quantum computation. The ideal low pass and high pass filters
are considered and quantum schemes for convolution are presented. The method of
the Fourier transform is used with one addition qubit to prepare the quantum
superposition for the inverse quantum Fourier transform.
