Basis Transformation Circuit for Fewer Two-Qubit Gates
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Solution Overview
Problem
Existing quantum computation methods face inefficiencies due to increased computational complexity and noise levels from two-qubit gates in basis transformation circuits, particularly when using general commutativity (GC) for observable partitioning, which affects the number of executions and overall computational efficiency.
Innovation Solution
A method to reduce the number of two-qubit gates in basis transformation circuits by selecting observables based on the number of characters other than 'I' in their Pauli strings, optimizing the selection process to minimize the use of such gates through appropriate weighting coefficients and partitioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If partitioning is performed under QWC, then basis transformation is achieved using single-qubit operations, but the number of partitions increases
Solution Approach 1:
The patent changes the commutativity criterion parameter from QWC to GC, allowing observables to be grouped based on general commutativity rather than qubit-wise commutativity. This parameter change enables the use of two-qubit gates in basis transformation circuits, which reduces the number of partitions needed and improves computational efficiency while maintaining measurement accuracy through proper error correction
2Productivity
If partitioning is performed under GC, then the number of partitions is reduced, but the basis transformation circuit includes many two-qubit gates
Solution Approach 1:
The patent converts the harmful effect of two-qubit gate noise into a beneficial outcome by implementing error correction mechanisms. The system uses multiple measurements and classical post-processing to correct errors introduced by two-qubit gates, thereby maintaining measurement accuracy while achieving the reduced partition count and improved computational efficiency that GC enables
3Reliability
If the number of partitions increases, then the number of quantum circuit executions increases, but the computational efficiency deteriorates
Solution Approach 1:
The patent changes the partitioning parameter from QWC-based to GC-based grouping, which significantly reduces the number of partitions required. This parameter change directly reduces the number of quantum circuit executions needed, thereby reducing computation time and improving efficiency while still achieving complete measurement coverage through the GC commutativity criterion
Data Source
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AI summary
An information processing apparatus calculates, for each of a plurality of simultaneously measurable observables included in an observable group, an index value based on the number of characters other than I included in a Pauli string representing the observable. The information processing apparatus selects a predetermined number of observables from the observable group, based on the index values. The information processing apparatus then creates a basis transformation circuit that transforms an expectation value of each of the predetermined number of selected observables, included in an execution result of a quantum circuit that performs quantum computation based on a problem to be solved, into a measurement result of a single qubit.