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 <EOS>