QKD Trusted-Area Transmission for Longer Distance and Key Rate
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Solution Overview
Problem
Existing Quantum Key Distribution (QKD) systems face limitations in achievable key rates and communication distances due to high propagation losses and noise, particularly in long-distance satellite and fibre-based communications, with single-photon requirements posing bottlenecks and vulnerabilities to multiphoton states.
Innovation Solution
A QKD transmission system that transmits multiphoton pulses within a trusted area extending from the transmitter to a defined distance, allowing high-energy pulses to propagate to a receiver, with active monitoring to ensure security, enabling a controllable tradeoff between communication distance and key rate by ensuring single-photon conditions at the receiver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If single-photon pulses are transmitted to ensure security, then security is maintained, but communication distance and key rate are limited due to propagation losses
Solution Approach 1:
The transmission path is segmented into a trusted area (where multiphoton pulses can propagate) and an untrusted area (where single-photon conditions must be maintained). This segmentation allows the system to use high-energy multiphoton pulses for distance extension while maintaining single-photon security requirements at the receiver end.
Solution Approach 2:
The system dynamically adjusts the trusted area distance parameter to optimize the tradeoff between communication distance and key rate. By changing this parameter, the system can adapt to different security requirements and channel conditions, allowing multiphoton transmission within the trusted area while ensuring single-photon conditions at the receiver.
2Length of stationary object
If transmission power is increased to extend communication distance, then communication distance improves, but security is compromised due to multiphoton states
Solution Approach 1:
The system establishes a trusted area in advance where multiphoton pulses can propagate securely. By pre-defining this trusted region and calculating its maximum distance based on security requirements, the system enables high-power transmission within this area while guaranteeing that single-photon conditions are maintained at the receiver boundary.
Solution Approach 2:
The trusted area acts as an intermediary zone that mediates between the high-power multiphoton transmission needs and the single-photon security requirements. Within this intermediate region, the system can use multiphoton states, but the design ensures that by the time pulses reach the receiver, they satisfy single-photon conditions.
3Reliability
If single-photon conditions are enforced throughout the entire transmission path, then security is maximized, but communication distance is limited due to exponential propagation losses
Solution Approach 1:
The transmission path is divided into a trusted area where relaxed security conditions allow multiphoton transmission, and an untrusted area where strict single-photon conditions apply. This segmentation enables distance extension by allowing higher energy transmission in the trusted zone while maintaining security in the untrusted zone.
Solution Approach 2:
Different security requirements are applied to different regions of the transmission path. The trusted area near the transmitter allows multiphoton states with relaxed security monitoring, while the region near the receiver maintains strict single-photon conditions. This local differentiation optimizes both distance and security.
Data Source
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AI summary
The present invention concerns a Quantum Key Distribution (QKD) transmission system (2,3) comprising a transmitter (31) and a receiver (32), wherein the transmitter (31) is configured to transmit a multiphoton pulse to the receiver (32) through a trusted area (23,33) that extends from the transmitter (31) towards the receiver (32) up to a trusted distance (D) from the transmitter (31); wherein the transmitter (31) is configured to transmit the multiphoton pulse with a transmission power such that a single-photon pulse propagates out from the trusted area (23,33) up to reach the receiver (32).