Technical Program

Paper Detail

Paper Title Secret key distillation over a pure loss quantum wiretap channel under restricted eavesdropping
Paper IdentifierFR4.R4.1
Authors Ziwen Pan, Kaushik P. Seshadreesan, University of Arizona, United States; William Clark, Mark R. Adcock, General Dynamics Mission Systems, United States; Ivan B. Djordjevic, University of Arizona, United States; Jeffrey H. Shapiro, Massachusetts Institute of Technology, United States; Saikat Guha, University of Arizona, United States
Session Secret Keys
Location Odéon, Level 3
Session Time Friday, 12 July, 16:40 - 18:00
Presentation Time Friday, 12 July, 16:40 - 17:00
Manuscript  Click here to download the manuscript
Abstract Quantum cryptography provides absolute security against an all-powerful eavesdropper (Eve). However, in practice Eve’s resources may be restricted to a limited aperture size so that she cannot collect all paraxial light without alerting the communicating parties (Alice and Bob). In this paper we study a quantum wiretap channel in which the connection from Alice to Eve is lossy, so that some of the transmitted quantum information is inaccessible to both Bob and Eve. For a pure loss channel under such restricted eavesdropping, we show that the key rates achievable with a two-mode squeezed vacuum state, heterodyne detection, and public classical communication assistance—given by the Hashing inequality—can exceed the secret key distillation capacity of the channel against an omnipotent eavesdropper. We report upper bounds on the key rates under the restricted eavesdropping model based on the relative entropy of entanglement, which closely match the achievable rates. For the pure-loss channel under restricted eavesdropping, we compare the secret-key rates of continuous-variable (CV) quantum key distribution (QKD) based on Gaussian-modulated coherent states and heterodyne detection with the discrete variable (DV) decoy state BB84 QKD protocol based on polarization qubits encoded in weak coherent laser pulses.