Almost-classical quantum computers

By means of a subgroup of the 2 X 2 unitary matrices, i.e. a subgroup Q of U(2), acting on a single qubit, we create a group X, acting on w qubits. If Q equals the group of order 2 consisting of the follower and the inverter, we recover S_{2^w}, i.e. the permutation matrices describing a classical reversible computer acting on w bits. If Q is another group of two 2 X 2 matrices, then a new kind of computing appears.

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