Quantum locking of classical correlations and quantum discord of classical-quantum states

Abstract

A locking protocol between two parties is as follows: Alice gives an encrypted classical message to Bob which she does not want Bob to be able to read until she gives him the key. If Alice is using classical resources, and she wants to approach unconditional security, then the key and the message must have comparable sizes. But if Alice prepares a quantum state, the size of the key can be comparatively negligible. This effect is called quantum locking. Entanglement does not play a role in this quantum advantage. We show that, in this scenario, the quantum discord quantifies the advantage of the quantum protocol over the corresponding classical one for any classical-quantum state.

10 pages, submitted to IJQI special issue

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• Quantum discord as a resource in quantum communication
• Quantum Correlations in Large-Dimensional States of High Symmetry
• Criteria for measures of quantum correlations
• The quantumness of correlations revealed in local measurements exceeds entanglement
• Monogamy of Quantum Discord by Multipartite Correlations
• A pedagogical overview of quantum discord
• Light Cone-Like Behavior of Quantum Monogamy Score and Multisite Entanglement
• Non-Gaussian quantum discord for Gaussian states
• Quantum Coherence and Intrinsic Randomness
• Improving the performance of quantum cryptography by using the encryption of the error correction data
• Maximally dense coding capable quantum states
• Discording power of quantum evolutions
• Quantum enigma machines and the locking capacity of a quantum channel
• Quantum discord amplification induced by quantum phase transition via a cavity-Bose-Einstein-condensate system
• Constructive Feedback of Non-Markovianity on Resources in Random Quantum States
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• Maxwell's demons in multipartite quantum correlated systems
• Continuous-variable quantum enigma machines for long-distance key distribution
• Shielding quantum discord through continuous dynamical decoupling
• Channel discrimination power of bipartite quantum states
• Approximate broadcasting of quantum correlations
• Time-invariant Discord: High Temperature Limit and Initial Environmental Correlations
• Frozen and Invariant Quantum Discord under Local Dephasing Noise
• Approximation, Proof Systems, and Correlations in a Quantum World
• Dephasing effects on quantum correlations and teleportation in presence of state dependent bath
• Quantum Discord and Entanglement of Quasi-Werner States based on Entangled Coherent States
• Quantum Discord Dynamics for Two-Level Atom Initially in Thermal Equilibrium Interacting with n-Photon State