Analysis of N-qubit perfectly controlled teleportation schemes from the controller's point of view

TL;DR

This paper evaluates the control power in N-qubit controlled teleportation schemes, establishing the minimum control required for authority and analyzing various schemes to ensure fidelity and control power.

Contribution

It introduces a quantitative measure of control power in N-qubit teleportation and revisits schemes to determine the minimum control needed for authority.

Findings

Controllers must control at least N bits for N-qubit teleportation.

Minimum control power is necessary to prevent unauthorized teleportation.

General rules for ensuring fidelity and control power are discussed.

Abstract

We quantitatively analyze and evaluate the controller's power in $N$-qubit controlled teleportation schemes. We calculate the minimum control power required to ensure the controller's authority such that the teleportation fidelity without the controller's permission is no more than the classical bound. We revisit several typical controlled teleportation schemes from the controller's point of view and evaluate the control power in these schemes. We find that for teleporting arbitrary N-qubit states, each controller should control at least N bits of useful information to ensure his/her authority over the protocol. We also discuss the general rules that must be satisfied by controlled teleportation schemes to ensure both teleportation fidelity and control power.