Exact minimum and maximum of yield with a finite number of decoy light intensities

TL;DR

This paper derives exact bounds for the yield in decoy state quantum key distribution when using a finite set of light intensities, improving the precision of yield estimation in quantum communication.

Contribution

It introduces exact minimum and maximum yield bounds for finite decoy intensities, enhancing the accuracy of quantum key distribution security analysis.

Findings

Exact bounds are achieved when all intensities are ≤ 1

Improved upper and lower bounds for asymptotic yield y_n

Bounds are exact for specific light intensity conditions

Abstract

In this paper, for the decoy state method using a finite number of decoy light intensities, we present an improved upper and lower bounds for the asymptotic yield y_n for n-photon states. In particular if all the light intensities are less than or equal to one, they are not only a lower or upper bound, but in fact are the exact minimum or maximum.