Entangling power of two-qubit gates on mixed states

Abstract

The ability to reach a maximally entangled state from a separable one through the use of a two-qubit unitary operator is analyzed for mixed states. This extension from the known case of pure states shows that there are at least two families of gates which are able to give maximum entangling power for all values of purity. It is notable that one of this gates coincides with a maximum discording one. We give analytical proof that such gate is indeed perfect entangler at all purities and give numerical evidence for the existence of the second one. Further, we find that there are other gates, many in fact, which are perfect entanglers for a restricted range of purities. This highlights the fact that many perfect entangler gates could in principle be found if a thorough analysis of the full parameter space is performed.

References in corpus (4)

• Maximally discordant mixed states of two qubits
• Discording power of quantum evolutions
• Entangling characterization of (SWAP)1/m and Controlled unitary gates
• On the distribution of entanglement changes produced by unitary operations

Cited by in corpus (6)

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• High-fidelity and robust controlled-Z gates implemented with Rydberg atoms via echoing rapid adiabatic passage
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• Imperfect Entangling Power of Quantum Gates
• Hierarchies among genuine multipartite entangling capabilities of quantum gates