  After introducing a bit-plane quantum representation for a multi-image, we
present a novel way to encrypt/decrypt multiple images using a quantum
computer. Our encryption scheme is based on a two-stage scrambling of the
images and of the bit planes on one hand and of the pixel positions on the
other hand, each time using quantum baker maps. The resulting quantum
multi-image is then diffused with controlled CNOT gates using a sine
chaotification of a two-dimensional H\'enon map as well as Chebyshev
polynomials. The decryption is processed by operating all the inverse quantum
gates in the reverse order.
