Quantum Cost Unitary Updates for Low-Noise Combinatorial Optimization
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Solution Overview
Problem
Conventional quantum approximate optimization algorithms face challenges in accurately solving combinatorial optimization problems due to noise in quantum computers, particularly when increasing the number of circuit layers, which leads to errors and reduces the ability to express arbitrary solutions.
Innovation Solution
An information processing method that updates cost unitary operators in a quantum circuit by adding first-order terms with new variational parameters to improve the ability to express arbitrary solutions without increasing the layer count, thereby reducing the likelihood of quantum bit errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of circuit layers is increased to improve the ability to express arbitrary solutions, then the solution accuracy is improved, but the number of quantum bits and circuit complexity increase, leading to more errors due to noise
Solution Approach 1:
The patent modifies the cost unitary operator by adding first-order terms with new variational parameters to the exponent part. This parameter change enhances the operator's ability to express arbitrary solutions without increasing the circuit layer count, thereby improving solution accuracy while avoiding additional noise from extra layers
Solution Approach 2:
The patent selectively updates only those cost unitary operators that correspond to quantum bits without first-order terms in the cost operator. This segmentation approach focuses computational resources on specific parts of the circuit that benefit most from the update, improving efficiency without proportionally increasing overall complexity
2Measurement precision
If the number of circuit layers is increased to improve the ability to express arbitrary solutions, then the solution accuracy is improved, but the reliability decreases due to quantum bit errors
Solution Approach 1:
By modifying the cost unitary operator parameters (adding first-order terms) rather than increasing circuit depth, the patent achieves better solution expression capability while maintaining the same physical circuit depth. This reduces exposure to noise and errors that accumulate with deeper circuits, thereby improving reliability
Solution Approach 2:
The patent creates an enhanced version of the cost unitary operator with additional first-order terms while maintaining the original circuit structure. This allows the system to benefit from the enhanced operator without replicating the entire circuit multiple times, reducing error accumulation
3Device complexity
If conventional cost unitary operators are used without first-order terms, then the circuit structure is simpler, but the ability to express arbitrary solutions is limited, reducing solution accuracy
Solution Approach 1:
The patent enhances the cost unitary operator by adding first-order terms (proportional to σz[i]) with new variational parameters to the exponent part. This parameter modification enriches the operator's functional capability to express arbitrary solutions while maintaining the same circuit layer structure, thus improving solution accuracy without proportionally increasing complexity
Data Source
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AI summary
An information processing device 100 judges, with respect to at least any one of multiple quantum bits in a quantum circuit 110, whether a corresponding first-order term is present in a cost operator 101. When the first-order term corresponding to any one of the plurality of quantum bits is not present the information processing device 100 updates at least any one of the cost unitary operators so that the first-order term corresponding to the any one of the quantum bits and to which a new first variational parameter is assigned is included in the exponent part. The information processing device 100 solves a combinatorial optimization problem based on multiple mixer unitary operators and the multiple cost unitary operators after updating at least the any one of the cost unitary operators.