Local Cloning of Entangled Qubits

TL;DR

This paper investigates the limits of locally cloning entangled qubits, revealing that more entanglement than previously thought is required for certain cloning tasks, especially for nonmaximal states and multiple Bell states.

Contribution

It provides the first detailed analysis of the entanglement needed for local cloning of orthogonal entangled qubits, including nonmaximal states and multiple Bell states.

Findings

More than 1 ebit of entanglement is needed for certain nonmaximal states.

Cloning all three Bell states requires at least log2 3 ebits.

The entanglement cost varies depending on the states being cloned.

Abstract

We discuss the exact cloning of orthogonal but entangled qubits under local operations and classical communication. The amount of entanglement necessary in blank copy is obtained for various cases. Surprisingly this amount is more than 1 ebit for certain set of two nonmaximal but equally entangled states of two qubits system. To clone any three two qubits Bell states at least log2 3 ebit is necessary.