Quantum Optical Communication Using Photon Pair Segmentation
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Solution Overview
Problem
Conventional optical communication methods for quantum cryptography allow eavesdroppers to measure photons, even if their presence is detected, resulting in potential information leakage.
Innovation Solution
An optical communication system and method utilizing a photon pair generator, a polarizer, and a shutter to create correlated photon pairs with predetermined polarizations, making it difficult for eavesdroppers to intercept information by blocking one photon and detecting the other, with the polarizer direction set based on transmission information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If phase modulation is used to transmit information through photons, then information transmission capability is improved, but vulnerability to eavesdropping increases
Solution Approach 1:
The information transmission is divided into multiple time slots, with transmission periods alternating with non-transmission periods. During non-transmission periods, no photons are sent even though the polarizer direction may be set, creating gaps that prevent continuous eavesdropping while maintaining information transmission capability during active periods.
Solution Approach 2:
The polarizer direction is set in advance during non-transmission periods before actual photon transmission begins. This preliminary configuration of the transmission state without emitting photons allows the system to prepare information-carrying states while minimizing exposure to potential eavesdroppers.
2Productivity
If photons are transmitted continuously for efficient communication, then productivity is improved, but ease of detecting eavesdropping deteriorates
Solution Approach 1:
The system employs periodic transmission with alternating transmission and non-transmission time slots. This periodic pattern creates predictable gaps in photon emission that facilitate eavesdropping detection mechanisms while maintaining sufficient overall transmission efficiency through the structured rhythm of active communication periods.
3Adaptability or versatility
If the polarizer direction is changed frequently to encode information, then adaptability is improved, but device complexity increases
Solution Approach 1:
The polarizer direction is determined and set in advance during non-transmission periods before photons are emitted. This preliminary determination separates the decision-making process from the transmission act itself, allowing flexible information encoding through polarizer orientation while simplifying the real-time transmission control mechanism.
Solution Approach 2:
The control of polarizer direction is segmented into discrete time slots corresponding to individual photon transmissions or groups of photons. Rather than continuous adjustment, the polarizer orientation is changed in stepped increments at defined intervals, reducing control complexity while maintaining encoding flexibility.
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
Significantly hampers eavesdropping attempts by ensuring that only predetermined photons are transmitted, reducing the likelihood of information interception and allowing for secure communication.
Implementation Method 1
a photon pair generator which generates a correlated photon pair
Implementation Method 2
a polarizer which is provided on an optical path of one photon of the correlated photon pair and direction of which is changeable based on information to be transmitted
Implementation Method 3
a shutter which is provided between the photon pair generator and the polarizer on the optical path of the one photon of the correlated photon pair and which is capable of blocking the one photon of the correlated photon pair
Implementation Method 4
a photon detector which is provided on an optical path of another photon of the correlated photon pair
Data Source
AI summary
The present invention provides an optical communication method and an optical communication system in which eavesdropping is more difficult than in conventional techniques. An optical communication system in one embodiment of the present invention comprises: a photon pair generator which generates a correlated photon pair; a polarizer which is provided on an optical path of one photon of the correlated photon pair and direction of which is changeable based on information to be transmitted; a shutter which is provided between the photon pair generator and the polarizer on the optical path of the one photon of the correlated photon pair and which is capable of blocking the one photon of the correlated photon pair; and a photon detector which is provided on an optical path of another photon of the correlated photon pair.