Mutual information superadditivity and unitarity bounds

Understand

We derive the property of strong superadditivity of mutual information arising from the Markov property of the vacuum state in a conformal field theory and strong subadditivity of entanglement entropy.

• We show this inequality encodes unitarity bounds for different types of fields.
• These unitarity bounds are precisely the ones that saturate for free fields.
• This has a natural explanation in terms of the possibility of localizing algebras on null surfaces.