[Paper Review] Continuous variable one-sided device independent quantum key distribution

Nathan Walk, Howard M. Wiseman+1 more|arXiv (Cornell University)|May 26, 2014

Quantum Computing Algorithms and Architecture1 references9 citations

TL;DR

This paper derives secret key rate bounds for continuous-variable quantum key distribution using entropic uncertainty relations in the continuous variable regime, achieving one-sided device independence—enabling secure key exchange with only one trusted device. The approach is experimentally feasible with current technology over realistic channels, even for protocols using only coherent states.

ABSTRACT

By extending recently developed entropic uncertainty relations in the continuous variable regime we derive bounds upon the secret key rate of Gaussian modulated continuous variable quantum key distribution protocols in the limit of long key length. For several protocols the bounds obtained in this manner can be shown to be one sided device independent, including a protocol that uses only coherent states. Though the derived uncertainty relation is not tight, and neither are the subsequent key rates, we find that one-sided device independent schemes are experimentally achievable with existing technology for transmission over realistic channels.

Motivation & Objective

• To extend entropic uncertainty relations to the continuous variable regime for quantum key distribution.
• To derive practical bounds on secret key rates for Gaussian-modulated CV-QKD protocols in the long-key limit.
• To establish one-sided device independence for multiple CV-QKD protocols, including those using only coherent states.
• To demonstrate the feasibility of one-sided device-independent schemes with current experimental technology.
• To analyze the performance of these protocols over realistic, lossy quantum channels.

Proposed method

• Leverages recently developed entropic uncertainty relations tailored for continuous variables.
• Applies these relations to bound the uncertainty of measurement outcomes in Gaussian-modulated CV-QKD protocols.
• Derives secret key rate bounds under the assumption of one trusted device (e.g., sender), enabling one-sided device independence.
• Considers the asymptotic limit of long key lengths to simplify the analysis and improve practicality.
• Evaluates the bounds for protocols using coherent states, showing their compatibility with one-sided device independence.
• Assesses the robustness of the derived bounds under realistic channel conditions, including loss and noise.

Experimental results

Research questions

• RQ1 Can entropic uncertainty relations in the continuous variable regime be used to derive meaningful secret key rate bounds for CV-QKD?
• RQ2 To what extent can one-sided device independence be achieved in Gaussian-modulated CV-QKD protocols?
• RQ3 Are the derived key rate bounds tight enough to be experimentally relevant?
• RQ4 Can protocols using only coherent states achieve one-sided device independence under realistic channel conditions?
• RQ5 What is the practical feasibility of implementing one-sided device-independent CV-QKD with current technology?

Key findings

• The derived secret key rate bounds are one-sided device independent, meaning only one party (e.g., the sender) needs to be trusted.
• The approach applies to multiple CV-QKD protocols, including those based solely on coherent states.
• Although the uncertainty relation and resulting key rates are not tight, they remain experimentally relevant.
• The schemes are feasible with existing technology, particularly over realistic, lossy quantum channels.
• The results demonstrate that one-sided device-independent CV-QKD is achievable in practice, even without full device independence.