Quantum key distribution over noisy channels by the testing state method

TL;DR

This paper introduces the testing state method, enabling quantum key distribution over various noisy channels without error correction or distillation, regardless of noise strength.

Contribution

The paper proposes a novel testing state method that allows QKD over noisy channels without distillation, applicable to multiple noise types and strengths.

Findings

QKD can be implemented over arbitrarily noisy channels using the testing state method.

The method functions as an error-correcting procedure adaptable to different noise models.

It extends the feasibility of secure quantum communication in practical noisy environments.

Abstract

Quantum key distribution(QKD) might be the most famous application of quantum information theory. The idea of QKD is not difficult to understand but in practical implementations, many problems are needed to be solved, for example, the noise of the channels. Previous works usually discuss the estimate of the channels and employ error-correcting procedures, whose feasibility and efficiency depend on the strength of the noise, or assist with entanglement distillation procedures, which often result in a large consumption of states while not all states can be distilled. This paper aims to study QKD over noisy channels including Pauli noises, amplitude damping noises, phase damping noises, collective noises as well as mixtures of them, in any strength without distillations. We provide a method, called the testing state method, to implement QKD protocols without errors over arbitrarily strength noisy channels. The method can be viewed as an error-correcting procedure, and can also be employed for other tasks.