Quantum Circuit Rewriting for Non-Destructive Debugging
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Solution Overview
Problem
Standard debugging methods for quantum circuits are not applicable on quantum computers due to the irreversible nature of measurement, which changes the execution outcome, making it impossible to observe the internal state of qubits.
Innovation Solution
A system and method that automates quantum circuit debugging by rewriting source circuits into instrumented circuits with breakpoints, executing these circuits to obtain measurement data, and processing the data to infer internal states and processes without altering the execution result, using techniques like state and process tomography and reconstruction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If measurement is performed to observe internal state of qubits, then debugging information is obtained, but the execution outcome is changed and the process becomes irreversible
Solution Approach 1:
The patent creates multiple copies of the quantum circuit, each instrumented to measure different internal states. Instead of measuring one circuit and losing its execution outcome, multiple copies are executed to gather comprehensive debugging information while each copy preserves its own execution integrity
Solution Approach 2:
The patent applies circuit rewriting rules before execution to automatically insert instrumentation code at strategic locations. This preliminary instrumentation prepares the circuit to capture debugging information without requiring measurement during execution, thus preserving the execution outcome
2Ease of operation
If standard debugging methods are applied to quantum circuits, then code execution can be observed, but the irreversible nature of measurement makes internal state observation impossible
Solution Approach 1:
The patent introduces an intermediary circuit rewriting layer that translates high-level debugging intentions into instrumented quantum circuits. This intermediary handles the complexity of state measurement and reconstruction, making debugging accessible without requiring direct quantum measurement operations
Solution Approach 2:
The patent replaces direct quantum measurement (the mechanical act of observing qubit states) with classical post-processing techniques like state tomography. Instead of measuring qubits directly during execution, the system uses mathematical reconstruction methods to infer internal states from measurement data
3Loss of information
If instrumentation code is inserted into quantum circuits, then debugging information can be obtained, but dead code is generated that needs to be removed
Solution Approach 1:
The patent segments the circuit optimization process into distinct phases: instrumentation insertion, execution, and dead code removal. This segmentation allows each phase to be handled independently with appropriate rules, maintaining debugging information while systematically eliminating dead code
Solution Approach 2:
The patent systematically identifies and removes dead code generated by instrumentation while preserving the essential measurement data. Circuit rewriting rules detect unreachable code paths and eliminate them, recovering from the complexity introduced by instrumentation
Data Source
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AI summary
Techniques for automating quantum circuit debugging are provided that simulate standard debugging behaviors. The technology includes rewriting a source quantum circuit into instrumented circuits based on instrumentation instruction information inserted into software code that corresponds to the source quantum circuit. The instrumented circuits can executed to obtain measurement data corresponding to different state data of qubits within the source quantum circuit. The measurement data can be processed to output generated information corresponding to one or more internal states or processes of a quantum computer associated with the source quantum circuit.