6 Revisiting impossible quantum operations using principle of no - signalling and conservation of entanglement under LOCC

In this letter, we show the impossibility of the general operation introduced by Pati using two different but consistent principles (i) no-signalling (ii) conservation of entanglement under LOCC. Further, we define Hadamard operation for an arbitrary qubit and show its impossibility with the aid of the above two principles. The rules of quantum mechanics makes certain processes impossible. Neither we can clone an quantum state [1] nor we can delete one of the two identical copies of a arbitrary quantum state [2]. Operations like cloning, conjugation, complementing etc comes under the broad heading 'General Impossible operation' [3]. In the recent past impossibility of operations like cloning ,flipping and deletion had been shown from two fundamental principles namely (i) principle of no-signalling and(ii) conservation of entanglement under LOCC [4,5,6]. In this letter we show that 'General Impossible Operations'[3] which will act on the tensor product of an unknown quantum state and blank state at the input port to produce the