1. A quantum gate for carrying out a Grover's quantum algorithm using a certain binary function (f) defined on a space having a vector basis of n qubits, comprising a superposition subsystem carrying out a superposition operation on components of input vectors for generating components (O 11, O 12 ;... ; O 81, O 82 ) of superposition vectors on a second vector basis of n&plus;1 qubits, an entanglement subsystem carrying out an entanglement operation on components of said linear superposition vectors for generating components (Q 1,..., Q 8 ) of entanglement vectors, and an interference subsystem carrying out an interference operation on components of said entanglement vectors for generating components of output vectors, comprising at least an adder (HB 25 ), input with signals representative of even or odd components of an entanglement vector (Q 1,..., Q 8 ), generating a sum signal (SQ) representative of a weighted sum with a scale factor (½ n−1 ) of said even or odd components; an array of adders (HB 16,..., HB 23 ), each input with a respective signal representing an even or odd component, respectively, of an entanglement vector (Q 1,..., Q 8 ) and with said sum signal (SQ) and generating, as the difference between said sum signal (SQ) and a signal representing an even or odd component of an entanglement vector (Q 1,..., Q 8 ), a signal representing, an even or odd component, respectively, of an output vector (A 1,..., A 8 ).