Efficient quantum cryptography network without entanglement and quantum memory

TL;DR

This paper introduces an efficient quantum cryptography network protocol that uses d-dimensional polarized photons, avoiding entanglement and quantum memory, and employs nonorthogonal coding for security, making it more practical with current technology.

Contribution

The proposed protocol enables secure quantum communication without entanglement or quantum memory, utilizing single photons and decoy-photon techniques for enhanced practicality.

Findings

Protocol avoids entanglement and quantum memory requirements

Uses nonorthogonal coding for security against eavesdropping

Compatible with faint laser pulse implementation

Abstract

An efficient quantum cryptography network protocol is proposed with d-dimension polarized photons, without resorting to entanglement and quantum memory. A server on the network, say Alice, provides the service for preparing and measuring single photons whose initial state are |0>. The users code the information on the single photons with some unitary operations. For preventing the untrustworthy server Alice from eavesdropping the quantum lines, a nonorthogonal-coding technique (decoy-photon technique) is used in the process that the quantum signal is transmitted between the users. This protocol does not require the servers and the users to store the quantum state and almost all of the single photons can be used for carrying the information, which makes it more convenient for application than others with present technology. We also discuss the case with a faint laser pulse.