Quantum Circuit Equivalents for Non-Clifford Error Mitigation
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Solution Overview
Problem
Current quantum computers using noisy intermediate-scale quantum (NISQ) devices struggle to correct errors due to non-Clifford gates, limiting the effectiveness of quantum error mitigation techniques like randomized compiling (RC), which are only applicable to Clifford gates.
Innovation Solution
A method to convert non-Clifford gates into equivalent circuits using both Clifford and non-Clifford gates, enabling quantum error mitigation by executing multiple equivalent quantum circuits and averaging their results to mitigate errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If randomized compiling (RC) is applied to mitigate quantum errors, then coherent errors are reduced, but the technique is only applicable to Clifford gates and not non-Clifford gates
Solution Approach 1:
The patent segments the quantum gate operation into multiple equivalent circuits. Specifically, a single non-Clifford gate operation is divided into multiple alternative circuit implementations, each using different combinations of Clifford and non-Clifford gates. This segmentation allows RC to be applied to subsets of the circuit while maintaining overall functionality, thereby extending error mitigation capabilities to circuits containing non-Clifford gates.
Solution Approach 2:
The patent changes the parameter representation of quantum gates by introducing equivalent circuits with different gate compositions. Instead of treating each gate type as a fixed operation, the system represents gates as multiple equivalent circuit configurations with varying proportions of Clifford and non-Clifford gates. This parameter transformation enables the application of RC techniques to previously intractable non-Clifford gate operations.
2Reliability
If Clifford gates are used in quantum circuits for error mitigation, then quantum error mitigation can be applied, but the number of two-qubit gates increases
Solution Approach 1:
The patent applies partial RC techniques rather than requiring complete conversion to Clifford gates. By applying RC to only certain portions of the quantum circuit or to subsets of equivalent circuits, the system achieves error mitigation benefits without the excessive overhead of fully converting all gates to Clifford equivalents. This partial application reduces the number of additional two-qubit gates required while maintaining meaningful error mitigation capability.
Data Source
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AI summary
An information processing apparatus generates a second quantum circuit by replacing a first two-qubit gate in a first quantum circuit with a first equivalent circuit including a second two-qubit gate that performs a gate operation for a phase rotation with a first rotation angle. The information processing apparatus generates a third quantum circuit by replacing the first two-qubit gate in the first quantum circuit with a second equivalent circuit including a third two-qubit gate that performs a gate operation for a phase rotation with a second rotation angle. The information processing apparatus causes a quantum computer to execute the second quantum circuit and the third quantum circuit, and outputs the mean of the execution results as the execution result of the first quantum circuit.