Randomized Quantum Gate Benchmarking for Error Source Separation
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Solution Overview
Problem
Existing benchmarking techniques for quantum computers are limited in their universality and cannot effectively evaluate the fidelity of arbitrary quantum circuits, particularly failing to distinguish between infidelity caused by qubit decoherence and state preparation and measurement errors.
Innovation Solution
The implementation of fully-randomized benchmarking methods that generate and apply sequences of random unitary quantum gates with recovery gates to assess the fidelity of quantum gates, allowing for the separation of decoherence-induced infidelity from other error sources, thereby enhancing the universality of benchmarking across various quantum computing systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If existing benchmarking techniques are used, then the benchmarking process can be performed, but the techniques cannot be universally applied to arbitrary quantum circuits and cannot distinguish between different error sources
Solution Approach 1:
The patent segments the quantum gate sequence into distinct components: random unitary gates, the target quantum gate under test, and recovery gates. This segmentation allows separate measurement of different error contributions - specifically separating decoherence effects (which affect the entire sequence) from state preparation and measurement errors (which affect specific operations), thereby enabling universal benchmarking with precise error source identification
Solution Approach 2:
The patent introduces random unitary gates as intermediary elements between the target quantum gate and the measurement process. These intermediary gates serve as a buffer that allows the separation of error sources: by comparing sequences with and without the target gate surrounded by random unitary gates, the method can isolate decoherence effects from other error sources, achieving both universality and measurement precision
2Measurement precision
If fully-randomized benchmarking with multiple gate sequences is implemented, then accurate fidelity evaluation is achieved, but the complexity of generating and executing benchmark sequences increases
Solution Approach 1:
The patent creates a universal benchmarking framework where the same basic sequence structure (random unitary gates + target gate + recovery gate) can evaluate any arbitrary quantum gate. The method uses a standardized approach with configurable parameters (number of random gates m1, number of measurements) that can adapt to different quantum circuits without requiring complex gate-specific procedures, thus achieving high measurement precision with manageable complexity
Solution Approach 2:
The patent controls complexity through parameter optimization - specifically by selecting an appropriate number of random unitary gates (m1) and measurements that balances accuracy with computational feasibility. The method allows adjusting these parameters based on available resources, enabling accurate fidelity evaluation while managing the complexity of sequence generation and execution
Data Source
AI summary
Methods, apparatuses, and systems include: based on a parameter of a quantum gate, generating representations of mi random unitary quantum gates; determining a representation of a first quantum-gate sequence equivalent to an identity operator; determining a representation of a second quantum-gate sequence equivalent to the identity operator; sending, to a quantum computing device, hardware instructions corresponding to the representation of the first quantum-gate sequence the second quantum-gate sequence; receiving a first number of measurements of a qubit after applying the first quantum-gate sequence to the qubit for the first number of times by the quantum computing device and a second number of measurements of the qubit after applying the second quantum-gate sequence to the qubit for the second number of times by the quantum computing device; and determining a fidelity value of the quantum gate based on a first probability and a second probability.