SARG04

SARG04 is a quantum cryptography protocol derived from the first protocol of that kind, BB84.

Origin

Researchers built SARG04 when they noticed that by using the four states of BB84 with a different information encoding they could develop a new protocol which would be more robust when attenuated laser pulses are used instead of single-photon sources. SARG04 was defined by Scarani et al. in 2004 in Physical Review Letters as a prepare and measure version (in which it is equivalent to BB84 when viewed at the level of quantum processing).[1]

An entanglement-based version has been defined as well.[1]

Intended use

The intended use of SARG04 is in situations where the information is originated by a Poissonian source producing weak pulses (this means: mean number of photons < 1) and received by an imperfect detector.[1]

Modus operandi

The modus operandi of SARG04 is based on the principle that the hardware must remain the same (as prior protocols) and the only change must be in the protocol itself.[1]

In the original "prepare and measure" version, SARG04's two conjugated bases are chosen with equal probability.[1]

Double clicks are important for comprehending SARG04: double clicks work differently in BB84 and SARG04.[1]

Security

Kiyoshi Tamaki and Hoi-Kwong Lo were successful in proving security for one and two-photon pulses using SARG04.[1]

It has been confirmed that SARG04 is more robust than BB84 against incoherent PNS attacks.[1]

Unfortunately an incoherent attack has been identified which performs better than a simple phase-covariant cloning machine, and SARG04 has been found to be particularly vulnerable in single-photon implementations when Q >= 14.9%.[1]

Comparison with BB84

In single-photon implementations, SARG04 was theorised to be equal with BB84, but experiments shown that it is inferior.[1]

Bibliography

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 http://arxiv.org/abs/quant-ph/0505035

See also