Partial Swapping, Unitarity and No-signalling

TL;DR

This paper demonstrates that the impossibility of partially swapping quantum state parameters aligns with fundamental principles like unitarity and no-signalling in quantum mechanics.

Contribution

It shows that the known impossibility of partial parameter swapping is consistent with core quantum principles such as unitarity and no-signalling.

Findings

Partial swapping of quantum parameters is impossible.

Impossibility aligns with unitarity and no-signalling principles.

Reinforces fundamental constraints in quantum information theory.

Abstract

It is a well known fact that an quantum state $|\psi(\theta,\phi)>$ is represented by a point on the Bloch sphere, characterized by two parameters $\theta$ and $\phi$. In a recent work we already proved that it is impossible to partially swap these quantum parameters. Here in this work we will show that this impossibility theorem is consistent with principles like unitarity of quantum mechanics and no signalling principle.