Fault tolerant quantum key distribution based on quantum dense coding with collective noise

TL;DR

This paper introduces two quantum key distribution protocols that are resilient to collective noise by using three-qubit entangled states and quantum dense coding, enabling secure communication with reduced measurement complexity.

Contribution

It proposes novel QKD protocols utilizing logical qubits and Bell-state analysis to combat collective noise, simplifying measurement requirements compared to previous methods.

Findings

Protocols effectively counteract collective noise effects.

Securely transmit two bits of information per two physical qubits.

Potential for direct secret message transmission in low-loss channels.

Abstract

We present two robust quantum key distribution protocols against two kinds of collective noise, following some ideas in quantum dense coding. Three-qubit entangled states are used as quantum information carriers, two of which forming the logical qubit which is invariant with a special type of collective noise. The information is encoded on logical qubits with four unitary operations, which can be read out faithfully with Bell-state analysis on two physical qubits and a single-photon measurement on the other physical qubit, not three-photon joint measurements. Two bits of information are exchanged faithfully and securely by transmitting two physical qubits through a noisy channel. When the losses in the noisy channel is low, these protocols can be used to transmit a secret message directly in principle.