Quantum Chip Qubit Routing to Minimize SWAP Gates
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Solution Overview
Problem
In quantum computing, the qubit allocation problem arises when qubits are not sufficiently near to interact effectively, necessitating the movement of information across qubits, which is computationally expensive and error-prone due to the need for additional SWAP gates, increasing computation time and error likelihood.
Innovation Solution
A method is developed to construct a routed circuit for qubit allocation on a quantum chip structure using a graph representation, employing a scoring system with discounted and not discounted scores, and dynamic programming to minimize the number of SWAP gates required, optimizing qubit placement and routing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If SWAP gates are inserted to move qubit information to enable interaction, then qubit connectivity is improved, but computation time increases and error likelihood increases
Solution Approach 1:
The patent applies preliminary action by performing qubit placement and routing optimization before the quantum circuit execution. The system analyzes the quantum circuit graph and quantum chip graph in advance to determine optimal qubit-to-physical-qubit mappings and necessary SWAP gate sequences, thereby minimizing computation time during actual execution while ensuring qubit connectivity requirements are met.
Solution Approach 2:
The patent segments the quantum circuit into a graph representation where qubits and gates are nodes and operations are edges. This segmentation allows the system to independently optimize placement and routing for different circuit portions, identifying minimal SWAP gate sequences needed for each segment while maintaining overall circuit functionality and reducing total computation time.
2Adaptability or versatility
If SWAP gates are inserted to move qubit information to enable interaction, then qubit connectivity is improved, but the number of gates increases
Solution Approach 1:
The system performs preliminary analysis of the quantum circuit and chip architecture to pre-determine optimal qubit mappings and minimal SWAP gate sequences before circuit compilation. This advance planning reduces the number of SWAP gates needed compared to runtime decisions, thereby reducing circuit complexity while maintaining necessary qubit connectivity.
Solution Approach 2:
The patent employs dynamic programming to explore multiple placement and routing configurations, dynamically selecting the optimal sequence of SWAP gates that achieves required qubit connectivity with minimal gate count. The algorithm adapts its search strategy based on circuit characteristics and chip topology, reducing unnecessary SWAP operations and overall circuit complexity.
3Adaptability or versatility
If SWAP gates are inserted to move qubit information to enable interaction, then qubit connectivity is improved, but error likelihood increases
Solution Approach 1:
The system performs preliminary optimization of qubit placement and routing to minimize the number of SWAP gates required before circuit execution. By pre-calculating optimal mappings between logical qubits and physical qubits based on circuit structure and chip topology, the system reduces the total number of error-prone SWAP operations, thereby improving computation reliability while maintaining necessary qubit connectivity.
Solution Approach 2:
The patent incorporates feedback mechanisms where the system evaluates different placement and routing configurations, selecting sequences that minimize SWAP gate count. The algorithm uses cost functions that weigh connectivity requirements against error probabilities, providing feedback-driven optimization that reduces error likelihood while achieving required qubit interactions.
Data Source
AI summary
The present disclosure may include methods, devices, and systems for constructing a routed circuit to allocate information qubits. The routed circuit may comprise at least one two-qubit gate and zero or more one-qubit gates on a quantum chip structure represented by a graph comprising vertices and edges.