Quantum Key Distribution Using Decoy State Protocol

Sellami Ali,Shuhairi Saharudin,M.R.B Wahiddin

doi:10.3844/ajeassp.2009.694.698

Sellami Ali, Shuhairi Saharudin + Show 1 more

Open Access

https://doi.org/10.3844/ajeassp.2009.694.698

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Abstract

Problem statement: Quantum key distribution provides unconditional security guaranteed by the fundamental laws of quantum physics. Unfortunately, for real-life experimental set-ups, which mainly based on faint laser pulses, the occasional production of multi-photons and channel loss make it possible for sophisticated eavesdroppers to launch various subtle eavesdropping attacks including the Photon Number Splitting (PNS) attack. The decoy state protocols recently proposed to beat PNS attack and to improve dramatically distance and secure key generation rate of Quantum Key Distribution (QKD). Approach: Objective of this study was experimental implementation of weak decoy + vacuum states QKD for increasing the performance of QKD system. To show conceptually how simple it was to apply the weak decoy + vacuum state idea to a commercial QKD system, we chosen ID-3000 commercial quantum key distribution system manufactured by id quantique. To implement the weak decoy + vacuum state protocol, we had to add some new optical and electronics components to id quantique and to attenuate each signal to the intensity of either signal state or weak decoy or vacuum state randomly. Results: In our implementation, the attenuation will be done by placing a VOA (variable optical attenuator) in Alice’s side. Specifically, our QKD system required the polarizations of 2 pulses from the same signal to be orthogonal. Therefore the VOA must be polarization independent so as to attenuate the two pulses equally. The VOA utilized in experiment to attenuate signals dynamically was Intensity Modulator (IM). We had implemented weak + vacuum protocol on a modified commercial QKD system over a 25 km of telecom fibers with an unconditionally secure key rate of 6.2931×10-4 per pulse. Conclusion: By making simple modifications to a commercial quantum key distribution system, we could achieve much better performance with substantially higher key generation rate and longer distance than QKD system without decoy state.

Highlights

Quantum Key Distribution (QKD) has drawn many attentions from scientists
Different from the classical cryptography, Quantum Key Distribution (QKD)[1,2,3] can help two remote parties to set up the secure key by noncloning theorem[4]
To show conceptually how simple it is to apply the decoy state idea to a commercial QKD system, we chose ID-3000 commercial Quantum Key Distribution system manufactured by id quantique

Summary

Introduction

Quantum Key Distribution (QKD) has drawn many attentions from scientists. Different from the classical cryptography, Quantum Key Distribution (QKD)[1,2,3] can help two remote parties to set up the secure key by noncloning theorem[4]. Proofs for the unconditional security over noisy channel have been given[5,6,7,8]. In view of implementation, “perfect” devices are always very hard to build. Most up-to-date QKD systems substitute the desired perfect single photon sources by heavily attenuated coherent laser sources. QKD can be performed with these laser sources over more than 120 km of telecom fibers[9,10]

Methods

Results

Conclusion