A computer implemented method for encoding bits by qubits to perform information-theoretically secure quantum gate computation, according to which pairs of quantum bits consisting of a first qubit as an encoding of “0” and a second qubit as an encoding of “1” are randomly selected, such that the first and second qubits are orthogonal to each other as quantum states and are interchanged by a NOT gate. Each qubit rotating to a desired initial direction and then each rotated qubit is further rotated to its antipodal direction by applying a quantum NOT or CNOT gate to the each rotated qubit, without any knowledge about the desired direction. A unitary gate is further applied over the qubits, using an ancillary |0 qubit that creates an equally weighted superposition of the qubits.