Fig. 1

Diagram summarising our method of generalising the classical irreversible neuron with Heaviside activation function, first to a reversible neuron represented by a permutation matrix (P), and finally to a quantum reversible computation, represented by a unitary operator (U). The top neuron is a classical neuron taking two inputs in₁ and in₂ and giving a corresponding output out.¹ \(a_j^{(l)}\) labels the output of the j-th neuron in the l-th layer of the network