Quantum Channel Round-Trip Latency Validation With Alternating Test Signals
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Solution Overview
Problem
In quantum communication systems, determining the precise round-trip latency between remote devices is crucial for accurate qubit projection measurements, but existing methods are inadequate for systems where the distance between sender and receiver nodes is not well-defined, such as due to thermal expansion or contraction of optical fibers.
Innovation Solution
A method involving the transmission of alternating first and second values as test signals, with validation signals, and using shift registers to adjust and refine an estimated round-trip latency value based on comparisons and bit flipping to achieve accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the distance between sender and receiver nodes is not precisely known, then the round-trip latency cannot be accurately determined, but increasing measurement complexity may disrupt quantum state coherence
Solution Approach 1:
The patent segments the round-trip latency measurement into multiple discrete time-bin qubits, where each qubit represents a specific time slot. By dividing the measurement process into sequential time bins rather than attempting a single comprehensive measurement, the system achieves precise latency determination while maintaining quantum coherence throughout the measurement sequence.
Solution Approach 2:
The patent implements preliminary action by pre-establishing synchronized clocks at both sender and receiver nodes before the actual quantum communication begins. This preliminary clock synchronization creates a reference framework that enables accurate round-trip latency measurement without requiring complex real-time adjustments that would disrupt quantum state coherence.
2Measurement precision
If thermal expansion or contraction of optical fibers occurs, then the physical distance changes and latency becomes inaccurate, but frequent remeasurement increases system complexity
Solution Approach 1:
The patent implements feedback through a bidirectional communication protocol where the receiver acknowledges receipt of time-bin qubits and the sender adjusts subsequent transmissions based on measured round-trip latency. This feedback mechanism continuously compensates for thermal expansion or contraction of optical fibers, maintaining latency accuracy without requiring complex manual recalibration or frequent complete remeasurements.
Solution Approach 2:
The patent utilizes parameter changes by encoding information in the temporal domain through time-bin qubits, where the timing parameters of qubit transmission and reception directly reflect the current optical path length. As thermal conditions change the physical distance, the time-bin parameters automatically adjust to reflect the new latency, providing continuous accuracy without additional measurement complexity.
Data Source
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AI summary
The present disclosure relates to a method for determining a round-trip latency of a communication channel in a communication system between a first device located at a first location and a second device located at a second location that is remote from the first location, wherein the communication system comprises a clock unit configured to generate clock cycles, comprising: - setting an estimated round trip latency value by the first device, wherein the estimated round trip latency value is represented as a binary number and represents a latency measured in clock cycles of the clock unit; - generating and sending, during a first period, a first test signal by the first device to the second device, wherein the first test signal comprises alternating first values and second values, wherein first and second values are sent at each clock cycle of the clock unit; - saving by the first device each first and second value of the first test signal for at least a duration that corresponds to the estimated round trip latency value; - receiving the first test signal at the second device; - sending, by the second device to the first device, upon receiving the first test signal, a validating signal that is generated by the second device and is based on the first test signal, wherein the validating signal comprises at least second values when second values from the first test signal are received; - receiving the validating signal at the first device; - comparing the validating signal with the first test signal sent during the first period; and - determining if the estimated round trip latency value is correct based on the comparing of the validating signal and the first test signal.