Expandable multi-user quantum key distribution network system and key distribution method thereof

Abstract

The invention discloses an expandable multi-user quantum key distribution network system and a key distribution method thereof; wherein the system comprises a point-to-multipoint quantum key distribution system composed of a quantum key transmitting terminal and a plurality of quantum key receiving terminals. The key distribution method includes the steps: firstly, the quantum key transmitting terminal namely the transmitter and a plurality of quantum key receiving terminals namely the receivers carry out quantum key distribution, the transmitter and each receiver all share a random quantum key; secondly, any two receivers send a request to the transmitter, the transmitter compares the two quantum keys shared with the receivers bit by bit and sends the comparison result to the two receivers, and the two receivers can obtain the quantum key shared by the transmitter and the other receiver by combining the own quantum key shared with the transmitter. The invention is reasonable in design and convenient in use and operation, and has strong user capacity expansion capability, long transmission distance and good user functionality; and any two legal receivers can share the key.

Description

technical field [0001] The invention belongs to the technical field of quantum key distribution, and in particular relates to an expandable multi-user quantum key distribution network system and a key distribution method thereof. Background technique [0002] Quantum key distribution provides an absolutely secure random sequence for both sides of legal communication in different places, usually called quantum key. The security of quantum key is proved to be absolutely safe in theory, even if the advent of quantum computer does not pose a threat to it . This is because a single quantum state is used as an information carrier to transmit information, usually called a qubit. The security of this qubit is guaranteed by the uncertainty principle in quantum mechanics and the no-cloning theorem of unknown quantum states. therefore. This absolutely secure quantum key will first be used in military, national security and other fields, and become a new battlefield for scientists fro...

AI Technical Summary

Problems solved by technology

The disadvantage is: the security of the network system depends on the trustworthiness of the nodes, that is, each node is trustworthy

However, its disadvantages are as follows: First, the service scope is small: nodes do not have the relay amplification function, and can only serve metropolitan or local areas; Second, the network capacity is poorly scalable: the network capacity is limited by device parameters, Moreover, these two types of optical devices have a large insertion loss. As the capacity of network users increases, they can only be expanded by cascading optical devices, so the insertion loss also increases, which will shorten the quantum key distribution transmission. distance, and reduce the rate at which quantum keys are generated

Disadvantages: 1. Small service range: nodes do not have relay amplification function, and can only serve metropolitan or local areas; 2. Poor user functions: only one-to-multi-point key distribution can be realized in the network; , the expansion performance is poor, and the expansion of the user capacity of the network seriously affects the transmission distance and distribution rate of the quantum key

Disadvantages: technical implementation is currently difficult

However, under the existing experimental conditions, it is not yet possible to achieve

[0008] In summary, the existing multi-user quantum key distribution system based on optical beam splitters has the following disadvantages: 1. Poor user functions: only one-to-multi-point key distribution can be realized in the network; 2. User capacity expansion performance Poor: The expansion of capacity reduces the transmission distance and generation efficiency of the key; three, the transmission distance is short

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