Quantum Gate Fusion and Decomposition for Error Reduction
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Solution Overview
Problem
Current quantum computing systems face challenges in reducing errors, particularly in distributed systems where inter-module communication leads to lower fidelity due to increased error-proneness and decoherence, with existing solutions primarily focusing on reordering qubit indices without modifying the quantum gate sequence.
Innovation Solution
Implementing 'fuse-and-decompose' operations in a quantum computing compiler, where many quantum gates are fused into a unitary operation and then decomposed into alternative sequences to reduce algorithm error and complexity, thereby minimizing inter-module communication and error rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If quantum gates are executed in distributed quantum systems with frequent inter-module communication, then quantum computations can be performed across multiple modules, but error rates increase and fidelity decreases
Solution Approach 1:
The patent combines multiple quantum gates into a single composite gate operation. By merging sequential gate operations into one unified quantum operation, the system reduces the number of times qubits need to be transferred between modules, thereby maintaining distributed computing capability while minimizing communication-induced errors and decoherence events.
Solution Approach 2:
The patent performs preliminary compilation and optimization of quantum gate sequences before execution. By pre-processing the quantum circuit to identify and combine gates that operate on the same qubits, the system prepares an optimized gate sequence that minimizes inter-module communication requirements before the actual quantum computation begins.
2Reliability
If quantum gates are fused and decomposed to reduce inter-module communication, then error rates decrease and fidelity improves, but gate sequence complexity increases
Solution Approach 1:
The patent segments the quantum gate sequence into groups of gates that operate on the same qubits or overlapping qubit sets. Each segment is then combined into a composite gate, and segments are arranged to minimize cross-module communication. This segmentation approach reduces overall complexity by creating modular, self-contained gate groups rather than dealing with the full complex sequence at once.
Solution Approach 2:
The patent changes the parameter representation of quantum gates by combining multiple gate parameters into a single composite gate operation. Instead of specifying individual gate parameters (rotation angles, axes, etc.) for each sequential gate, the system represents the combined effect as a single unitary transformation with its own set of parameters, simplifying the overall gate sequence description.
3Reliability
If qubit indices are reordered without modifying gate sequences, then some error reduction is achieved, but the potential for error reduction through gate fusion is lost
Solution Approach 1:
The patent performs preliminary analysis and reordering of quantum gates during the compilation stage, before the quantum computation is executed. By identifying gates that can be combined and repositioning them optimally in the gate sequence, the system prepares a configuration that maximizes error reduction opportunities while maintaining the original computational logic and functionality.
Solution Approach 2:
The patent introduces dynamic reconfiguration of the gate sequence based on the physical layout of qubits across modules. Instead of using a fixed gate sequence, the system dynamically adjusts the ordering and grouping of gates to optimize for the specific hardware architecture, enabling adaptive error reduction while preserving computational correctness.
Data Source
AI summary
Apparatus and method for error reduction in distributed quantum computing via fusing-and-decomposing gates. For example, one embodiment of an apparatus comprises: a quantum module comprising a plurality of qubits; unitary generation logic to combine a group of quantum gates to form at least one unitary operation; decomposition logic to decompose the unitary operation into multiple alternative gate sequences comprising either exact gate sequences or approximate gate sequences; and selection logic to evaluate the multiple alternative gate sequences based on a cost function to identify at least one of the gate sequences.