Quantum Communication System Using Intensity-Multiplexed Reference Pulses
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Quantum communication systems face challenges in maintaining stability and identifying errors due to phase and polarization drifts, which can be caused by eavesdropping or system variations, leading to increased bit error rates and difficulty in detecting unauthorized access.
Innovation Solution
A quantum communication system that uses pulses of different intensities, where reference pulses with higher intensity are intermixed with data pulses to enable active stabilization and calibration, allowing real-time correction of phase and polarization drifts, and providing a code division technique to differentiate between data and reference signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If calibration is performed periodically to maintain phase stability, then phase drift is corrected, but system dead time increases and productivity decreases
Solution Approach 1:
The patent embeds reference pulses within the continuous data pulse stream, allowing phase calibration to occur continuously throughout operation rather than requiring periodic interruptions. This enables the system to maintain phase stability without creating dead time, as the reference pulses are transmitted concurrently with data pulses through the same quantum channel.
Solution Approach 2:
The patent uses periodic reference pulses interspersed with data pulses to provide continuous calibration feedback. By repeating the reference pulse pattern at regular intervals within the data stream, the system achieves continuous phase monitoring and correction without stopping data transmission, thereby eliminating dead time while maintaining stability.
2Stability of the object's composition
If separate reference pulses are transmitted to enable real-time stabilization, then phase and polarization drift are corrected, but device complexity increases
Solution Approach 1:
The patent merges the reference pulse transmission and data pulse transmission into a single integrated quantum channel. By multiplexing reference and data pulses in the time domain within the same physical channel, the system eliminates the need for separate reference channels and associated synchronization equipment, thereby reducing overall device complexity while enabling real-time stabilization.
Solution Approach 2:
The patent makes the quantum channel universal by serving dual purposes: transmitting both data pulses and reference pulses through the same channel. This multi-functional approach eliminates the need for dedicated reference pulse transmission infrastructure, reducing system complexity while maintaining the ability to perform real-time phase and polarization calibration.
3Measurement precision
If reference pulses are sent with higher intensity to improve detection, then calibration accuracy improves, but photon number splitting attack vulnerability increases
Solution Approach 1:
The patent uses partial action by transmitting reference pulses with moderate intensity—higher than data pulses for detectability, but not excessively high. This balanced approach provides sufficient signal strength for accurate calibration while avoiding the extreme intensity levels that would create significant vulnerability to photon number splitting attacks. The reference pulses are intense enough for reliable detection but controlled to maintain security.
Data Source
AI summary
A quantum communication system including a sending unit and a receiving unit, said sending unit comprising a photon source assembly configured to output a stream of pulses of light having at least two different intensities and a memory configured to store information for determining which pulses should be reference pulses and which pulses should be data pulses, the average intensity of reference pulses being different to the average intensity of data pulses, the receiving unit comprising a memory for storing information for identifying the position of reference pulses within the stream of pulses and a processor for determining the calibration of the quantum communication system from the reference pulses.