Superactivation of multipartite unlockable bound entanglement

Area of Science:

• Quantum Information Science
• Quantum Optics
• Entanglement Theory

Background:

• Multipartite bound entanglement (BE) is a quantum resource.
• Superactivation is a protocol to distill entanglement from BE states.
• Previous work proposed superactivation theoretically by Shor et al. in 2003.

Purpose of the Study:

• To experimentally realize the superactivation of multipartite bound entanglement.
• To demonstrate the distillation of Einstein-Podolsky-Rosen (EPR) entangled states from two multipartite BE states.
• To show the superadditivity of quantum entanglement.

Main Methods:

• Generation of two four-partite unlockable BE states in a continuous-variable regime.
• Coupling thermal states with Gaussian noise into submodes of EPR entangled states using beam splitters.
• Performing a superactivation operation involving measurements and feedback on the two BE states.

Main Results:

• The first experimental realization of multipartite bound entanglement superactivation.
• Successful distillation of an EPR entangled state between two designated parties.
• Demonstration that two BE states are required for distillation, highlighting entanglement superadditivity.

Conclusions:

• The experiment confirms the feasibility of entanglement superactivation.
• Quantum entanglement exhibits superadditivity, where multiple states can yield a distillable entangled state that individual states cannot.
• This work opens avenues for enhanced entanglement distillation protocols in quantum information processing.