Quantum Circuit Compilation via Non-Intersecting Subtree Selection
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Solution Overview
Problem
Quantum computing faces challenges in efficiently implementing quantum circuits for surface code architectures due to the need for error correction and manipulation of qubits beyond their coherence time.
Innovation Solution
A method is proposed to optimize the implementation of quantum circuits using a directed acyclic graph (DAG) to select a subset of rotations that maximize the number of involved rotations or qubits without intersecting subtrees, thereby reducing the number of time steps required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If quantum circuits are implemented using surface code architecture for error correction, then reliability is improved, but the number of time steps required increases
Solution Approach 1:
The quantum circuit is segmented into multiple layers of rotations, where each layer contains a subset of rotations that can be implemented in parallel. This segmentation allows the circuit to be executed in fewer time steps by processing multiple rotation layers simultaneously without compromising error correction reliability
Solution Approach 2:
The method dynamically selects which rotations to execute in each time step based on the quantum circuit's structure and error correction requirements. By adaptively choosing rotation subsets that maximize parallelization while maintaining subtree non-intersection, the system optimizes execution time without sacrificing reliability
2Productivity
If more rotations are selected in parallel, then productivity is improved, but device complexity increases due to subtree intersection constraints
Solution Approach 1:
Before executing rotations in parallel, the method performs preliminary analysis of the quantum circuit structure to identify rotation subsets that can be safely executed simultaneously. This preliminary action involves analyzing the tree structure and selecting rotation subsets that will not cause subtree intersections, thereby maximizing productivity while avoiding complexity issues
Solution Approach 2:
The method creates a simplified representation (copy) of the quantum circuit's tree structure to analyze and select parallel rotation subsets. By working with this copied structure rather than the full complex circuit directly, the system can efficiently identify parallel execution opportunities without being overwhelmed by the full circuit complexity
Data Source
AI summary
A technique for implementing a quantum circuit is provided, where the quantum circuit includes qubits and operators executed on the qubits. The operators include a sequence of π/4 Pauli rotation gates. A surface code layout includes an arrangement of the quantum circuit on a quantum chip, where the arrangement includes at least a tree with a plurality of subtrees, each rotation gate corresponding to a subtree. The technique includes iteratively generating a directed acyclic graph (DAG) of the quantum circuit, where a front layer of the DAG is a set of rotations that can be effectively implemented at each iteration. The technique includes selecting a subset of the rotations (a “selected subset”) in the front layer in which the subtrees are arranged not to intersect (“non intersecting subsets”).