Application of the no-signaling principle to obtain quantum cloners for any allowed value of fidelity

Official URL: http://dx.doi.org/10.1103/PhysRevA.87.042314

Special relativity forbids superluminal influences. Using only the no-signaling principle and an assumption about the form of the Schmidt decomposition, we show that for any allowed fidelity there is a unique approximate qubit cloner which can be written explicitly. We introduce the prime cloners whose fidelities have multiplicative property and show that the fidelity of the prime cloners for the infinite copy limit is 1/2.