Quantum cryptography with polarization, phase and time encoding

TL;DR

This paper introduces a novel quantum cryptography protocol that encodes information in polarization, phase, and time, enabling secure key distribution even under high noise conditions.

Contribution

It presents a new non-interferometric quantum cryptography method using temporal and polarization superpositions to encode information in high-dimensional qudits.

Findings

Allows secret key generation with higher noise tolerance

Uses time-based phase determination instead of interference

Supports complex qudit encoding with D ≥ 4

Abstract

We develop and present a quantum cryptography concept in which phase determinations are made from the time that a photon is detected, as opposed to where the photon is detected, and hence is a non-interferometric process. The phase-encoded quantum information is contained in temporal and polarization superpositions of single photon states, forming a complex qudit of Hilbert dimension D equal to or greater than 4. Based on this, we have developed a new quantum key distribution protocol that allows the generation of secret key in the presence of higher noise than is possible with other protocols.