Quantum Time Measurement Using Shared Clock and Bit String Extraction
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Solution Overview
Problem
Existing time measurement methods for photons, such as TDC modules, face challenges with drift due to temperature changes, requiring extensive computing resources and complicating high-speed system operations in quantum communication systems.
Innovation Solution
A method and apparatus that receive START and STOP signals, convert them into bit strings, extract rising edges, and determine time intervals using a shared clock, eliminating the need for delay chains and external TDC modules, thereby improving integration and meeting high-speed requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If TDC module uses delay chains to measure time of arrival, then measurement function is achieved, but temperature drift occurs and requires real-time correction consuming computing resources
Solution Approach 1:
The patent extracts the time measurement function from the complex TDC module with delay chains and separates it into a dedicated time measurement unit. This unit uses a simple counter to count clock cycles between START and STOP signals, eliminating the need for temperature correction systems while maintaining measurement functionality.
Solution Approach 2:
The patent creates a simplified copy of the time measurement function that uses a counter and clock signal instead of the original delay chain mechanism. This copy performs the essential time measurement task without the temperature sensitivity and correction requirements of the original TDC module.
2Measurement precision
If TDC module performs real-time temperature correction, then measurement accuracy is maintained, but computing resources are heavily consumed
Solution Approach 1:
The time measurement unit is designed to be self-sufficient by using a stable internal clock signal and counter mechanism that does not require external temperature correction. The system serves itself by relying on the inherent stability of the clock signal rather than requiring additional correction computations.
3Stability of the object's composition
If TDC module implements temperature correction, then drift is compensated, but system speed is reduced
Solution Approach 1:
The patent uses a stable clock signal as a preliminary reference that inherently resists temperature drift. By establishing this stable time reference in advance and using it for measurement, the system achieves both stability and high-speed operation without requiring real-time correction during the measurement process.
Data Source
AI summary
A method and apparatus for measuring time, and a programmable controller for a quantum communication device are provided. The method includes: receiving a START signal and a STOP signal; sampling the START signal and the STOP signal by using a same clock to generate a START bit string corresponding to the START signal and a STOP bit string corresponding to the STOP signal; extracting a rising edge of the START signal from the START bit string, and extracting a rising edge of the STOP signal from the STOP bit string; and determining a time interval between the START signal and the STOP signal based on a count of bits between the rising edge of the START signal and the rising edge of the STOP signal and based on a period of the clock.