Quantum-Logic Circuit Verification via Direct-Sum Invariance Groups

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Solution Overview

Problem

Testing quantum-logic circuits with multiple states is resource-intensive due to the need to verify numerous input combinations, unlike binary logic, which limits the efficiency of conventional testing methods.

Innovation Solution

The use of direct sums and invariance groups to identify permutations that do not change the output of partially symmetric quantum-logic circuits, allowing for the reduction of the number of necessary tests by grouping inputs and generating a direct sum of permutation operations that preserve the circuit's functionality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional testing methods are used on quantum-logic circuits with multiple states, then complete verification of all input combinations is achieved, but the resource cost and complexity of testing increases prohibitively

Engineering Contradiction:
Improveverification completenessVSAvoidtesting complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the set of all possible input combinations into equivalence classes based on symmetry relationships. Instead of testing every individual input combination, the testing process is divided into testing one representative from each equivalence class. This segmentation reduces the testing scope from exponential to polynomial complexity while maintaining complete verification through the use of invariance groups that capture symmetric relationships among inputs.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent creates invariance groups that serve multiple functions: they identify symmetric relationships among inputs, define equivalence classes of input combinations, and generate test suites that automatically cover all symmetric variants. These groups act as universal structures that can be applied to any quantum-logic circuit with symmetric properties, making the testing methodology broadly applicable and efficient.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If the number of input states in quantum-logic circuits increases, then the computational power and functionality are improved, but the number of required tests increases exponentially

Engineering Contradiction:
Improvecircuit functionalityVSAvoidtesting efficiency
Core Design Contradiction:
Adaptability or versatilityVSProductivity

Solution Approach 1:

The patent changes the parameter of interest from individual input combinations to symmetry-based equivalence classes. By transforming the testing problem from state-space enumeration to group-theoretic analysis, the methodology achieves polynomial scaling with respect to the number of inputs and states. The invariance groups capture the essential functional relationships without requiring exponential sampling of the state space.

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If all possible input combinations are tested to ensure correct operation, then testing accuracy is maximized, but the time and resources required become prohibitively expensive

Engineering Contradiction:
Improvetesting accuracyVSAvoidtesting time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent performs preliminary analysis to identify invariance groups and symmetry relationships among circuit inputs before the actual testing begins. This preliminary action involves analyzing the circuit's functional properties to determine which input permutations produce equivalent outputs. By pre-computing these symmetry relationships, the methodology eliminates redundant tests while ensuring complete coverage of functionally distinct input combinations, thereby maintaining testing accuracy without the exponential time cost.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentUS10393807B2Reducing complexity when testing quantum-logic circuits
Publication Date: 2019.08.27 KYNDRYL INC
  • US10393807B2 patent drawing
  • US10393807B2 patent drawing

AI summary

A method and associated systems for using direct sums and invariance groups to optimize the testing of partially symmetric quantum-logic circuits is disclosed. A test system receives information that describes the architecture of a quantum-logic circuit to be tested. The system uses this information to organize the circuit's inputs into two or more mutually exclusive subsets of inputs. The system computes a direct sum of a set of groups associated with the subsets in order to generate an invariance group that contains one or more invariant permutations of the circuit's inputs. These invariant permutations can be used to reduce the number of tests required to fully verify the circuit for all possible input vectors. Once one specific input vector has been verified, there is no need to test other vectors that can be generated by performing any one of the invariant permutations upon the previously verified vector.