Controlled rotation

Patent Granted PROBLEM TO BE SOLVED: To constitute a controlled rotation operation in a short exchange gate row in a three-quantum bit decoherence-free subspace/system. ; SOLUTION: The quantum state that is expressed as the source of a four-dimensional Hilbert space is mapped to the source of the four-dimensional Hilbert space. There are 19 gate rows (t1 to t7, t2', t3', t5' and t7') for making the rotational angle of the controlled rotation gates to be a predetermined rotational angle.