  In this work we show that the most general class of anti-unitary operators
are nonphysical in nature through the existence of incomparable pure bipartite
entangled states. It is also shown that a large class of
inner-product-preserving operations defined only on the three qubits having
spin-directions along x, y and z are impossible. If we perform such an
operation locally on a particular pure bipartite state then it will exactly
transform to another pure bipartite state that is incomparable with the
original one. As subcases of the above results we find the nonphysical nature
of universal exact flipping operation and existence of universal Hadamard gate.
Beyond the information conservation in terms of entanglement, this work shows
how an impossible local operation evolve with the joint system in a nonphysical
way.
