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arXiv:2105.00035

Long-distance quantum key distribution based on the physical loss control

N. S. Kirsanov, N. R. Kenbaev, Asel Sagingalieva, Dmitry Anatolevich Kronberg, V. M. Vinokur, Gordey B. Lesovik

Published Apr 30, 2021• 2 citations
arXivHTMLPDF

Abstract

Existing quantum cryptography is resistant against secrecy-breaking quantum computers but suffers fast decay of the signal at long distances. The various types of repeaters of propagating quantum states have been developed to meet the challenge, but the problem is far from being solved. We step in the breach and put forth long-distance high secrecy optical cryptography, creating the fast quantum key distribution over distances up to 40,000 kilometers. The key element of the proposed protocol is the physical control over the transmission line.

DOI
10.48550/arxiv.2105.00035

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Existing quantum cryptography is resistant against secrecy-breaking quantum computers but suffers fast decay of the signal at long distances. The various types of repeaters of propagating quantum states have been developed to meet the challenge, but the problem is far from being solved. We step in the breach and put forth long-distance high secrecy optical cryptography, creating the fast quantum key distribution over distances up to 40,000 kilometers. The key element of the proposed protocol is the physical control over the transmission line.
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Quantum cryptography revolutionizes secure information transfer, providing defense against both quantum and classical computational attacks. The primary challenge in extending the reach of quantum communication comes from the exponential decay of signals over long distances. We meet this challenge by experimentally realizing the Quantum-Protected Control-Based Key Distribution (QCKD) protocol, utilizing physical control over signal losses. By ensuring significant non-orthogonality of the leaked quantum states, this control severely constrains eavesdroppers' capacities. We demonstrate the performance and scale of our protocol by experiments over a 1707 km long fiber line. The scalability of the QCKD opens the route for globally secure quantum-resistant communication.
Abstract Secure long distance communications protecting the transmitting of sensitive information vital for business and advanced technologies from being accessed by unauthorized individuals, is one of the major challenges of modern life. The existing means of transmitted data protection are vulnerable to upcoming quantum computer attacks. Yet, remarkably, the quantum mechanics that engendered a threat to secure communications offers a guaranteed protection against the malicious attacks allowing to develop novel quantum key distribution (QKD). The major problem of the long-distance transmission arises due to essential signal decay in optical channels occurring at distances about a hundred kilometers. We resolve this problem by an original Terra Quantum QKD (TQ-QKD) protocol using semiclassical pulses containing enough photons for random bit encoding and exploiting erbium amplifiers to retranslate photon pulses and, at the same time, ensuring that at the chosen pulse intensity only a few photons can go outside the channel even at distances of about a hundred meters.As a result, an eavesdropper is incapable to utilize the lost part of the signal. A central component of the TQ-QKD protocol is the end-to-end loss control of the fiber-optic communication line. Our control precision reduces the degree of the signal leak below the detectable level, depriving an eavesdropper any possibility to efficiently utilize the lost part of the signal. Our work experimentally demonstrates the implementation of the TQ-QKD protocol allowing for a fully secure quantum key distribution over 1079 kilometers. Further refining of the transmitting scheme's components will expand the secure transmission scale over the global distances.
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The cryptographic communication has a lot of important applications, particularly in the magnificent prospects of private communication. As one knows, the security of cryptographic channel depends crucially on the secrecy of the key. The Vernam cipher is the only cipher system which has guaranteed security. In that system the key must be as long as the message and most be used only once. Quantum cryptography is a method whereby key secrecy can be guaranteed by a physical law. So it is impossible, even in principle, to eavesdrop on such channels. Quantum cryptography has been developed in recent years. Up to now, many schemes of quantum cryptography have been proposed. Now one of the main problems in this field is how to increase transmission distance. In order to use quantum nature of light, up to now proposed schemes all use very dim light pulses. The average photon number is about 0.1. Because of the loss of the optical fiber, it is difficult for the quantum cryptography based on one photon level or on dim light to realize quantum key-distribution over long distance. A quantum key distribution based on coherent state is introduced in this paper. Here we discuss the feasibility and security of this scheme.
Long-distance communication data cannot be safely sent over the Internet without strong key distribution mechanisms and long-term, secure communication routes. In recent days, distributing a secret key across faraway entities connected by an optical fibre or open space has been the goal of quantum key distribution. The previous quantum method challenge in guaranteeing the integrity of qubits makes long-distance communication a challenging endeavour. With a growing number of cyber dangers, it is more important than ever to guarantee safe interaction. Quantum computers can easily crack traditional key exchange techniques, which create shared secret keys for protection. A quantum key distributionbased secure communication model (QKD-SCM) has been suggested for large-scale networks to rapidly ascertain the bare minimum of quantum repeaters needed to provide end-to-end connections among all end hosts. The suggested QKD-SCM evaluates the safety and efficiency of existing point-to-point QKD systems. The QKD-SCM with Quantum repeaters setup breaks the channel into quantum memory (QM), which is climbable and allows for long-distance quantum communication. The end of the channel is used to produce entangled qubits. Experiments show that QKD-SCM can succeed in making long-distance networks very secure with less communication delay.