Four-qubit photonic system for publicly verifiable quantum random numbers and generation of public and private key

TL;DR

This paper presents a four-qubit photonic system capable of generating publicly verifiable quantum random numbers and secure keys, demonstrated experimentally with high verification rates and practical encryption applications.

Contribution

It introduces a configurable four-qubit photonic architecture for real-time quantum random number generation, entanglement verification, and key generation, with experimental validation and noise modeling.

Findings

Generated random bits at 185 kbps with 97.9% passing entanglement verification

Simultaneous public and private key generation from the same system

Experimental results align with theoretical noise models

Abstract

We theoretically propose and experimentally demonstrate the use of a configurable four-qubit photonic system to generate a publicly verifiable quantum random numbers, to perform entanglement verification, and to generate secure public and private key. Quantum circuits, to generate the desired four-qubit states and its experimental realization in the photonic architecture is carried out using photon pairs entangled in polarization and path degree of freedom. By performing measurements on the four-qubit system and accessing partial information of the four-qubit state for public verification, we generate publicly verified and purely secured random bits at the rate of 185 kbps from collective data of 370 kbps. When the system is used for generating public and private keys, an equal number of public and private keys are generated simultaneously. We also record about 97.9% of sampled bits from four-qubit states passing entanglement verification and demonstrate the use of public and private key generated for image encryption-decryption. The theoretical model of noise on the four-qubit state and its effect on the generation rate of verified and secured bits are in perfect agreement with the experimental results. This demonstrates the practical use of the small-scale multi-qubit photonic system for quantum-safe applications by providing the option for real-time verification of the security feature of the quantum system.