Harnessing high-dimensional temporal entanglement using limited interferometric setups

Abstract

High-dimensional entanglement has been shown to provide significant advantages in quantum communication. One of its most promising implementations is available in the time domain routinely produced in spontaneous parametric down-conversion . While advantageous in the sense that only a single detector channel is needed locally, it is notoriously hard to analyze, especially in an assumption-free manner as required for quantum key distribution (QKD) applications. We develop a complete analysis of high-dimensional entanglement in the polarization-time domain and show how to efficiently certify relevant density matrix elements and security parameters for QKD. In addition to putting past experiments on rigorous footing, we also develop a physical noise model and propose a setup that can further enhance the noise resistance of free-space quantum communication.