Eavesdropping on the BB84 Protocol using Phase-Covariant Cloning: Experimental Results

TL;DR

This paper experimentally investigates the security of the BB84 quantum key distribution protocol under realistic noisy conditions by measuring how much information an eavesdropper can gain using phase-covariant cloning.

Contribution

It introduces a reproducible test to assess BB84 security in practical noisy environments and provides experimental estimates of eavesdropper information gain.

Findings

Eavesdropper can obtain significant information using phase-covariant cloning.

Security thresholds depend on noise levels in the quantum channel.

The test helps evaluate BB84 security in real-world conditions.

Abstract

Though the BB84 protocol has provable security over a noiseless quantum channel, the security is not proven over current noisy technology. The level of tolerable error on such systems is still unclear, as is how much information about a raw key may be obtained by an eavesdropper. We develop a reproducible test to determine the security--or lack thereof--of the protocol in practice. This enables us to obtain an experimental estimate of the information that can be obtained using asymmetric phase-covariant cloning to eavesdrop on the BB84 protocol.