Quantum Circuit Gate Reduction for Lower-Noise VQE
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Solution Overview
Problem
Existing quantum computers face challenges in reducing the number of quantum gates to mitigate noise accumulation, which affects the accuracy of variational quantum eigensolver (VQE) calculations, particularly in quantum chemical calculations.
Innovation Solution
An information processing method that identifies and deletes gate elements from a quantum circuit where the second qubit to be operated has a predetermined relationship with a first qubit specified by an observable, generating a new quantum circuit with reduced gates while maintaining calculation accuracy by updating rotation angles of remaining gate elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of quantum gates is increased to improve calculation accuracy in VQE, then the precision of quantum chemical calculations is improved, but noise accumulation increases making correct computation results more difficult to obtain
Solution Approach 1:
The patent extracts and removes unnecessary gate elements from the quantum circuit that do not contribute to the calculation of the target observable. By identifying and deleting gates where the second qubit has a predetermined relationship with the first qubit specified by the observable, the circuit is simplified to contain only essential gates, reducing noise accumulation while preserving calculation accuracy.
Solution Approach 2:
The patent changes the parameters of the quantum circuit by selectively removing gate elements based on their relationship to the observable. This parameter change optimizes the circuit by eliminating redundant operations, thereby reducing the total number of gates and the associated noise while maintaining the necessary computational precision.
2Object-affected harmful factors
If the number of quantum gates is reduced to decrease noise accumulation, then noise in VQE calculations is reduced, but calculation accuracy may deteriorate
Solution Approach 1:
The patent selectively extracts only the harmful unnecessary gates from the circuit while preserving all gates that contribute to the observable calculation. This extraction process reduces noise by minimizing the gate count while maintaining calculation accuracy through intelligent selection of which gates to remove based on their relationship to the target observable.
3Device complexity
If gate elements are deleted from the quantum circuit, then the number of quantum gates is reduced, but the complexity of identifying removable gates increases
Solution Approach 1:
The patent applies a self-service approach where the quantum circuit itself provides the criteria for gate removal. By using the predetermined relationship between the second qubit of each gate and the first qubit specified by the observable, the system automatically identifies removable gates without requiring external complex analysis, thus reducing circuit complexity while keeping the identification process manageable.
4Measurement precision
If rotation angles of remaining gate elements are updated to maintain calculation accuracy after gate deletion, then computation precision is maintained, but the complexity of the information processing increases
Solution Approach 1:
The patent updates the rotation angles of remaining gate elements as a systematic parameter change process. This involves recalculating and adjusting the parameters of the surviving gates to compensate for the removal of other gates, thereby maintaining computation precision through controlled parameter optimization rather than complex structural modifications.
Data Source
AI summary
An information processing apparatus identifies a first gate element from a first quantum circuit including a plurality of gate elements each corresponding to a single electron excitation operator or a double electron excitation operator. The first gate element is a gate element in which a second qubit to be operated has a predetermined relationship with a first qubit specified by an observable to be calculated. Then, the information processing apparatus generates a second quantum circuit by deleting the identified first gate element from the first quantum circuit.