An integrated optical circuit for an optical neural network, the optical circuit being configured: to process a plurality of phase-encoded optical input signals (N in); and to provide a phase-encoded optical output signal (N out) as a function of the phase-encoded optical input signals (N in), the phase-encoded optical output signal (N out) emulating a neuron functionality with respect to the plurality of phase-encoded optical input signals (N in); the integrated optical circuit comprising: a reference waveguide configured to carry an optical reference signal (S r); a plurality of input waveguides configured to receive the plurality of phase-encoded optical input signals (N in), wherein phase differences (φ) between the optical reference signal (S r) and the optical input signals (N in) represent the respective phase of the respective phase-encoded optical input signal (N in); an output waveguide; an optical interferometer system configured: to superimpose the plurality of optical input signals (N in) and the optical reference signal (S r) into a plurality of first interference signals (I, I 1, I 2); and to superimpose the plurality of first interference signals (I, I 1, I 2) into a second interference signal (I 4); and a phase-shifting device configured to provide the phase-encoded optical output signal (N out) as a function of the second interference signal (I 4). to process a plurality of phase-encoded optical input signals (N in); and to provide a phase-encoded optical output signal (N out) as a function of the phase-encoded optical input signals (N in), the phase-encoded optical output signal (N out) emulating a neuron functionality with respect to the plurality of phase-encoded optical input signals (N in); the integrated optical circuit comprising: a reference waveguide configured to carry an optical reference signal (S r); a plurality of input waveguides configured to receive the plurality of phase-encoded optical input signals (N in), wherein phase differences (φ) between the optical reference signal (S r) and the optical input signals (N in) represent the respective phase of the respective phase-encoded optical input signal (N in); an output waveguide; an optical interferometer system configured: to superimpose the plurality of optical input signals (N in) and the optical reference signal (S r) into a plurality of first interference signals (I, I 1, I 2); and to superimpose the plurality of first interference signals (I, I 1, I 2) into a second interference signal (I 4); and a reference waveguide configured to carry an optical reference signal (S r); a plurality of input waveguides configured to receive the plurality of phase-encoded optical input signals (N in), wherein phase differences (φ) between the optical reference signal (S r) and the optical input signals (N in) represent the respective phase of the respective phase-encoded optical input signal (N in); an output waveguide; an optical interferometer system configured: to superimpose the plurality of optical input signals (N in) and the optical reference signal (S r) into a plurality of first interference signals (I, I 1, I 2); and to superimpose the plurality of first interference signals (I, I 1, I 2) into a second interference signal (I 4); and to superimpose the plurality of optical input signals (N in) and the optical reference signal (S r) into a plurality of first interference signals (I, I 1, I 2); and to superimpose the plurality of first interference signals (I, I 1, I 2) into a second interference signal (I 4); and