Hybrid Quantum-Classical System for Reducing Circuit Depth
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Solution Overview
Problem
Near-term quantum computers face challenges in initial state preparation due to noisy quantum gates, limiting the depth of quantum circuits and accuracy of simulations, particularly for NISQ computers.
Innovation Solution
A method is introduced to reduce the depth of quantum circuits by recursively removing redundant gates and re-optimizing circuit parameters, utilizing a hybrid quantum-classical approach to select and tune parameters, thereby reducing the number of non-trivial operations and improving state preparation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the depth of quantum circuit is increased to improve state preparation accuracy, then the accuracy of simulation is improved, but the noise from quantum gates increases and the circuit becomes more complex
Solution Approach 1:
The patent extracts and removes redundant gates from the quantum circuit through recursive analysis. The system identifies gates that do not contribute to the final state preparation and eliminates them, thereby reducing circuit depth while preserving the essential functionality needed for accurate state preparation.
Solution Approach 2:
The patent changes the parameters of the quantum circuit by re-optimizing the remaining gates after removal. The system adjusts gate parameters and re-tunes the circuit to maintain preparation accuracy despite the reduced depth, effectively finding optimal parameter configurations for the simplified circuit architecture.
2Manufacturing precision
If the number of gates in quantum circuit is increased to improve state preparation, then the accuracy is improved, but the number of non-trivial operations increases leading to more noise
Solution Approach 1:
The patent removes unnecessary gates that contribute to noise without affecting the core state preparation functionality. By extracting only the essential gates and eliminating redundant operations, the system reduces the total number of non-trivial operations and thereby decreases the cumulative noise in the quantum circuit.
Solution Approach 2:
The patent discards redundant gates that do not contribute to the final state, and recovers or compensates for their functional contribution by re-optimizing the remaining essential gates. This ensures that the state preparation accuracy is maintained while using fewer total gates, thus reducing noise accumulation.
3Reliability
If the circuit depth is reduced to decrease noise, then the reliability is improved, but the state preparation accuracy deteriorates
Solution Approach 1:
The patent re-optimizes the parameters of the remaining gates after depth reduction to compensate for the loss of functionality. By carefully adjusting gate parameters and re-tuning the circuit, the system maintains state preparation accuracy even with reduced circuit depth, effectively decoupling the relationship between depth and accuracy.
Solution Approach 2:
The patent employs iterative optimization where the circuit is repeatedly analyzed, gates are removed, parameters are re-optimized, and performance is evaluated. This feedback loop ensures that the reduced-depth circuit achieves the desired state preparation accuracy by continuously adjusting parameters based on performance measurements.
4Productivity
If redundant gates are removed to reduce circuit depth, then the productivity is improved, but the initial state preparation becomes more challenging
Solution Approach 1:
The patent segments the quantum circuit into essential and non-essential components through systematic analysis. By dividing the circuit into functional modules and identifying which gates are critical versus redundant, the system can selectively remove gates while preserving the essential state preparation functionality, making the optimization process more manageable and effective.
Data Source
AI summary
A method includes improved techniques for preparing the initial state of a quantum computer by reducing the number of redundant or unnecessary gates in a quantum circuit. Starting from an initial state preparation circuit ansatz, the method recursively removes gates and re-optimizes the circuit parameters to generate a reduced-depth state preparation.