Entanglement catalysis and resilience of entangled systems to local noise




Centre of New Technologies, University of Warsaw

March 29, 2023 12:30 PM

Quantum entanglement of pure states is usually quantified via the entanglement entropy, the von Neumann entropy of the reduced state. Entanglement entropy is closely related to entanglement distillation, a process for converting quantum states into singlets, which can then be used for various quantum technological tasks. The relation between entanglement entropy and entanglement distillation has been known only for the asymptotic setting, and the meaning of entanglement entropy in the single-copy regime has so far remained open. We close this gap by considering entanglement catalysis. We prove that entanglement entropy completely characterizes state transformations in the presence of entangled catalysts. The inverse process of distillation is entanglement dilution: singlets are converted into quantum states with less entanglement. While the usefulness of distillation is apparent, practical applications of entanglement dilution are less obvious. We show that entanglement dilution can increase the resilience of entangled quantum states to local noise. The increased resilience is observed even if diluting singlets into states with arbitrarily little entanglement.

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