Secret key distillation from shielded two-qubit states

Abstract

The quantum states corresponding to a secret key are characterized using the so-called private states, where the key part consisting of a secret key is shielded by the additional systems. Based on the construction, it was shown that a secret key can be distilled from bound entangled states. In this work, I consider the shielded two-qubit states in a key-distillation scenario and derive the conditions under which a secret key can be distilled using the recurrence protocol or the two-way classical distillation, advantage distillation together with one-way postprocessing. From the security conditions, it is shown that a secret key can be distilled from bound entangled states in a much wider range. In addition, I consider the case that in which white noise is added to quantum states and show that the classical distillation protocol still works despite a certain amount of noise although the recurrence protocol does not.

5 pages

References in corpus (4)

• Key distillation from quantum channels using two-way communication protocols
• Quantum key distribution based on private states: unconditional security over untrusted channels with zero quantum capacity
• Security of quantum key distribution protocols using two-way classical communication or weak coherent pulses
• Bound entangled states with nonzero distillable key rate

Cited by in corpus (1)

• Low-dimensional quite noisy bound entanglement with cryptographic key