Optical Signal Timing Alignment via Polarization Control
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Solution Overview
Problem
Conventional continuous-variable quantum key distribution (CV-QKD) systems face challenges in timing alignment between local-frequency optical pulse signals and quantum optical pulse signals, leading to inefficiencies and potential security risks due to interference from local-frequency light, especially when optical fiber lengths between the sender and receiver are not precisely matched.
Innovation Solution
A signal receiving apparatus and method that detects a reference pulse signal to generate a modulation pulse signal, allowing for the creation of a first local-frequency optical pulse signal with aligned timing, which is then used to interfere with both the reference and quantum optical pulse signals, improving timing alignment efficiency and reducing interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If time-division multiplexing is used to separate quantum optical pulse signal and local-frequency optical pulse signal, then crosstalk between signals is reduced, but timing alignment complexity increases
Solution Approach 1:
A polarization controller is introduced as an intermediary device to manage the separation and alignment of quantum optical pulse signals and local-frequency optical pulse signals. The polarization controller adjusts the polarization states to achieve signal separation without requiring complex time-division multiplexing control mechanisms, thereby reducing timing alignment complexity while maintaining crosstalk reduction.
2Adaptability or versatility
If optical fiber lengths are not precisely matched between sender and receiver, then system adaptability improves, but timing alignment accuracy deteriorates
Solution Approach 1:
The system employs dynamic polarization control that can adapt in real-time to varying optical fiber lengths and environmental conditions. The polarization controller dynamically adjusts polarization states to maintain accurate timing alignment between signals regardless of fiber length mismatches, thereby preserving timing alignment accuracy while enhancing system adaptability to different deployment scenarios.
3Measurement precision
If local-frequency light intensity is increased to improve signal detection, then detection accuracy improves, but interference with quantum optical pulse signal increases
Solution Approach 1:
The system applies different polarization states to the local-frequency optical pulse signal and quantum optical pulse signal, creating local quality differences that enable selective detection. By controlling polarization properties locally, the system can enhance detection accuracy through increased local-frequency light intensity while maintaining quantum signal integrity through polarization-based interference rejection.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the accuracy and efficiency of timing alignment between local-frequency and quantum optical pulse signals, resulting in improved interference and secure key generation with reduced vulnerability to local-frequency optical pulse signal attacks.
Implementation Method 1
the signal receiving module uses the first local-frequency optical pulse signal to interfere with the reference pulse signal and the quantum optical pulse signal separately, to obtain a raw key
Implementation Method 2
uses the first local-frequency optical pulse signal to interfere with the reference pulse signal and the quantum optical pulse signal separately
Data Source
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AI summary
Embodiments of this application relate to a signal receiving apparatus and method. The receiving apparatus includes: a signal receiving module, configured to detect a reference pulse signal in a received optical pulse signal, where the optical pulse signal includes the reference pulse signal and a quantum optical pulse signal; and a synchronization clock module, configured to obtain a modulation pulse signal based on the reference pulse signal; where a first intensity modulator in the signal receiving module is configured to obtain, based on the modulation pulse signal, a first local-frequency optical pulse signal having same timing as the optical pulse signal, and the signal receiving module uses the first local-frequency optical pulse signal to interfere with the reference pulse signal and the quantum optical pulse signal separately, to obtain a raw key. Using the receiving apparatus provided in the embodiments of this application can efficiently implement timing alignment between the first local-frequency optical pulse signal and the optical pulse signal, so as to ensure optimum interference between the first local-frequency optical pulse signal and the optical pulse signal, and obtain an accurate raw key.