Review on recent groundbreaking experiments on quantum communication with orthogonal states

TL;DR

This paper reviews recent experimental advances in quantum communication, focusing on two novel cryptographic schemes that challenge traditional resource requirements for secure quantum key distribution.

Contribution

It presents experimental results on two innovative quantum cryptographic protocols that operate with minimal assumptions and resources, expanding understanding of secure quantum communication.

Findings

Orthogonal-state-based protocol detects eavesdropping despite cloneability.

Counterfactual protocol enables communication without photon transmission.

Experimental validation of protocols challenging conventional QKD assumptions.

Abstract

In recent years Quantum Key Distribution (QKD) has emerged as the most paradigmatic example of Quantum technology allowing the realization of intrinsically secure communication links over hundreds of kilometers. Beyond its commercial interest QKD also has high conceptual relevance in the study of quantum information theory and the foundations of quantum mechanics. In particular, the discussion on the minimal resources needed in order to obtain absolutely secure quantum communication is yet to be concluded. Here we present an overview on our last experimental results concerning two novel quantum cryptographic schemes which do not require some of the most widely accepted conditions for realizing QKD. The first is Goldenberg-Vaidman protocol \cite{v}, in which even if only orthogonal states (that in general can be cloned without altering the state) are used, any eavesdropping attempt is detectable. The second is N09 protocol \cite{no} which, being based on the quantum counterfactual effect, does not even require any actual photon transmission in the quantum channel between the parties for the communication.