Enhancing quantum cryptography with quantum dot single-photon sources

TL;DR

This paper demonstrates that quantum dot single-photon sources, with tunable coherence, enhance quantum cryptography security and outperform traditional photon sources like lasers and down-conversion in key distribution tasks.

Contribution

It identifies optimal optical pumping schemes for quantum cryptography and benchmarks quantum dot sources against conventional sources, highlighting their security advantages.

Findings

Quantum dot sources offer higher security in quantum cryptography.

Phonon-assisted and two-photon excitation improve performance over resonant excitation.

Benchmarking shows quantum dot sources outperform attenuated lasers and down-conversion sources.

Abstract

Quantum cryptography harnesses quantum light, in particular single photons, to provide security guarantees that cannot be reached by classical means. For each cryptographic task, the security feature of interest is directly related to the photons' non-classical properties. Quantum dot-based single-photon sources are remarkable candidates, as they can in principle emit deterministically, with high brightness and low multiphoton contribution. Here, we show that these sources provide additional security benefits, thanks to the tunability of coherence in the emitted photon-number states. We identify the optimal optical pumping scheme for the main quantum-cryptographic primitives, and benchmark their performance with respect to Poisson-distributed sources such as attenuated laser states and down-conversion sources. In particular, we elaborate on the advantage of using phonon-assisted and two-photon excitation rather than resonant excitation for quantum key distribution and other primitives. The presented results will guide future developments in solid-state and quantum information science for photon sources that are tailored to quantum communication tasks.