Quantum Cryptography Synchronization via Optical Axis
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Solution Overview
Problem
Quantum cryptography communication systems face challenges in mobile applications, such as satellite communication, due to the need for phase synchronization and accurate clock alignment, which are difficult to maintain when relative positions between the transmitter and receiver change, and the inability to detect polarization axes and synchronize signals effectively.
Innovation Solution
A quantum cryptography communication apparatus and method that transmits strong pulse light communication signals and weak quantum cryptography signals on the same optical axis, allowing for synchronization without a classical communication path, and uses counters to detect relative time delays, enabling polarization axis detection and adjustment, even in mobile scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If phase synchronization is performed using synchronization signals for loopback, then synchronization between transmitter and receiver is achieved, but a classical communication path (optical fiber) becomes essential, preventing application to mobile communication
Solution Approach 1:
The invention extracts the synchronization function from the classical communication path and implements it directly in the quantum communication channel. The receiver generates loopback synchronization signals and sends them back through the quantum channel itself, eliminating the dependency on separate optical fiber infrastructure and enabling mobile communication applications.
Solution Approach 2:
The quantum communication channel is given multiple functions: it simultaneously transmits quantum cryptography signals and carries synchronization signals for loopback. This multi-functionality eliminates the need for separate classical communication paths and enables the system to work in mobile scenarios where dedicated optical fibers are unavailable.
2Measurement precision
If synchronization pulses are exchanged and phase is locked, then detection of weak quantum signals is ensured, but the loopback transmission path becomes essential, preventing mobile communication application
Solution Approach 1:
The invention removes the requirement for a dedicated loopback transmission path by implementing phase locking directly within the quantum communication channel. The receiver generates and returns synchronization pulses through the same quantum channel used for cryptography, enabling precise phase detection without infrastructure constraints.
3Loss of time
If the same optical clock signal is received in transmitter and receiver, then timing synchronization is achieved, but the method cannot cope with cases where clock signal is a data signal
Solution Approach 1:
The invention segments the communication signal into distinct components: data signal portions and synchronization signal portions. The synchronization signals are embedded within the overall communication stream at specific intervals, allowing the system to maintain timing synchronization while the main channel carries arbitrary data signals without conflict.
4Adaptability or versatility
If polarization base axis detection is performed between movable bodies, then quantum cryptography can be applied to mobile communication, but accurate time adjustment between transmission and reception systems becomes difficult
Solution Approach 1:
The invention performs preliminary time adjustment by having the receiver generate synchronization signals with predetermined timing relationships before actual quantum cryptography communication begins. This preliminary synchronization establishes a reference frame that accounts for system time differences, enabling accurate polarization base axis detection and subsequent mobile communication operations.
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
Enables quantum cryptography communication in mobile settings like satellite communication without the need for optical fibers, allowing for synchronization and polarization axis detection, thus overcoming previous limitations in phase synchronization and clock alignment.
Implementation Method 1
transmitter transmits relatively strong pulse light as a communication signal and relatively weak quantum cryptography signal to a receiver
Implementation Method 2
detecting an optical clock with a photodetector and inputting the output of the detection to a synthesizer
Data Source
AI summary
A quantum cryptography communication apparatus performs quantum cryptography communication between a transmitter and a receiver. The quantum cryptography communication apparatus includes first communicating unit transmitting and receiving a communication signal including relatively strong pulse light between the transmitter and the receiver, and second communicating unit transmitting and receiving a relatively weak quantum cryptography signal between the transmitter and the receiver in a period in which the communication signal is off and the attitude axis for the receiver can be adjusted to that for the transmitter by the second communicating unit.