Determination of optimal chain coupling made by embedding in D-wave quantum annealer

초록

The qubits in a D-wave quantum annealer (D-wave QA) are designed on a Pegasus graph that is different from the structure of a combinatorial optimization problem. This situation requires embedding with the chains connected by ferromagnetic coupling Jc between the qubits. Weak and strong Jc values induce chain breaking and enforcement of chain energy, which reduce the accuracy of quantum annealing (QA) measurements, respectively. In addition, we confirmed that even though the D-wave Ocean package provides a default coupling J(c)(default), it is not an optimal coupling J(c)(optimal) that maximizes the possible correct rate of QA measurements. In this paper, we present an algorithm how J(c)(optimal) with the maximum probability p for observing the possible lowest energy is determined. Finally, we confirm that the extracted J(c)(optimal) shows much better p than J(c)(default) in QA measurements of various parameters of frustrated and fully connected combinatorial optimization problems. The open code is available in https://github.com/HunpyoLee/OptimizeChainStrength. (C) 2024 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).https://doi.org/10.1116/5.0205511

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