Quantum Circuit Segmentation for Mid-Circuit Measurement Verification
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Solution Overview
Problem
Quantum circuits that cannot return to an initial state due to mid-circuit measurements pose challenges in evaluating correctness and optimizing parameters, leading to suboptimal execution results.
Innovation Solution
Divide the quantum circuit into partial circuits, add inverse circuits to each, and execute sub-circuits multiple times with varying parameters to evaluate and optimize parameter settings based on input-output state comparisons.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a quantum circuit includes mid-circuit measurements, then measurement capability is improved, but the ability to return to initial state is lost
Solution Approach 1:
The quantum circuit is divided into multiple segments or blocks. Inverse circuits are added to specific segments rather than the entire circuit, allowing partial reversibility. This segmentation enables correctness evaluation of individual segments while preserving mid-circuit measurements in other parts of the circuit.
Solution Approach 2:
Inverse circuits are constructed to reverse the operations of the original quantum circuit segments. By applying inverse operations (U†) to segmented portions of the circuit, the system can return to intermediate states and evaluate correctness without requiring the entire circuit to be reversible.
2Reliability
If inverse circuits are added to verify correctness, then correctness evaluation is improved, but circuit depth increases
Solution Approach 1:
Instead of adding inverse circuits to the entire quantum circuit, the method segments the circuit and adds inverse operations only to specific segments. This reduces the overall circuit depth increase while still enabling correctness evaluation of the critical segments.
Solution Approach 2:
The method applies inverse circuits partially rather than completely to the entire circuit. By selecting only critical segments for inversion and verification, the approach achieves sufficient correctness evaluation without the excessive circuit depth that would result from inverting the entire circuit.
3Reliability
If classical simulation is used to verify quantum computation, then correctness verification is improved, but scalability deteriorates
Solution Approach 1:
The patent introduces an intermediary verification mechanism using inverse circuits and mid-circuit measurements. This intermediary approach provides a middle ground between full classical simulation (which is accurate but uns scalable) and no verification (which is scalable but unreliable). The inverse circuit technique enables efficient verification that scales with the quantum circuit.
4Productivity
If parameter optimization is performed without correctness evaluation, then execution efficiency is improved, but computation accuracy deteriorates
Solution Approach 1:
The method performs preliminary correctness evaluation using inverse circuits and mid-circuit measurements before final parameter optimization. This preliminary verification ensures that parameter optimization is based on accurate correctness assessments, preventing degradation of computation accuracy while maintaining execution efficiency.
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AI summary
a quantum computation support program causing a computer to execute a process includes dividing a quantum circuit to be executed by a quantum computer into a plurality of partial circuits, generating, with respect to each of the plurality of partial circuits, a sub-circuit obtained by adding, after the partial circuit, an inverse circuit that causes the quantum computer to execute an inverse arithmetic operation of an arithmetic operation of the partial circuit, setting, with respect to each of a plurality of candidate values of a parameter set for causing the quantum computer to execute the quantum circuit, the candidate value as the parameter, and causing the quantum computer to execute the sub-circuit generated from each of the plurality of partial circuits a plurality of times, and determining, based on a comparison result between an input state and an output state when the sub-circuit is executed, a value to be set as the parameter in the execution of the quantum circuit from among the plurality of candidate values.