Entanglement, discord and the power of quantum computation

Abstract

We show that the ability to create entanglement is necessary for execution of bipartite quantum gates even when they are applied to unentangled states and create no entanglement. Starting with a simple example we demonstrate that to execute such a gate bi-locally the local operations and classical communications (LOCC) should be supplemented by shared entanglement. Our results point to the changes in quantum discord, which is a measure of quantumness of correlations even in the absence of entanglement, as the indicator of failure of a LOCC implementation of the gates.

Published version. More results are added

References in corpus (4)

• Quantum discord and the power of one qubit
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• Quantum discord and local demons
• How state preparation can affect a quantum experiment: Quantum process tomography for open systems

Cited by in corpus (8)

• Quantum discord for general two--qubit states: Analytical progress
• Experimentally Witnessing the Quantumness of Correlations
• Correlation approach to work extraction from finite quantum systems
• Quantum discord for the general two-qubit case
• Nonclassicality and criticality in symmetry-protected magnetic phases
• Theoretical insights on measuring quantum correlations
• Non-Gaussian features from Excited Squeezed Vacuum State
• On the Physical Explanation for Quantum Computational Speedup