Universal Optimal Gates Regarding Quantum Entanglement and Discord Generating

TL;DR

This paper investigates the entangling power of two-qubit gates, demonstrating that the  gate maximizes entanglement generation across various purities, complementing prior work on quantum discord.

Contribution

It introduces a comprehensive analysis of the entangling power of two-qubit gates using Cartan decomposition, highlighting the  gate's optimality for entanglement generation.

Findings

 gate produces maximal entanglement for various purities.

Analysis based on Cartan decomposition of two-qubit unitaries.

Complementary to previous work on quantum discord.

Abstract

Fernando Galve \emph{et al.} $[Phys. Rev. Lett. \textbf{110}, 010501 (2013)]$ introduced discording power for a two-qubit unitary gate to evaluate its capability to produce quantum discord, and found that a $\pi/8$ gate has maximal discording power. This work analyzes the entangling power of a two-qubit unitary gate, which reflects its ability to generate quantum entanglement in another way. Based on the renowned Cartan decomposition of two-qubit unitary gates, we show that the magic power of the $\pi/8$ gate produces maximal entanglement for a general value of purities for two-qubit states.