Optimizing QUBO on a quantum computer by mimicking imaginary time evolution

Fuente: arXiv
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Hauptverfasser: Chai, Yahui, Di Tucci, Alice
Format: Preprint
Veröffentlicht: 2025
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author Chai, Yahui
Di Tucci, Alice
author_facet Chai, Yahui
Di Tucci, Alice
contents We propose a hybrid quantum-classical algorithm for solving QUBO problems using an Imaginary Time Evolution-Mimicking Circuit (ITEMC). The circuit parameters are optimized to closely mimic imaginary time evolution, using only single- and two-qubit expectation values. This significantly reduces the measurement overhead by avoiding full energy evaluation. By updating the initial state based on results from last step iteratively, the algorithm quickly converges to the low-energy solutions. With a pre-sorting step that optimizes quantum gate ordering based on QUBO coefficients, the convergence is further improved. Our classical simulations achieve approximation ratios above 0.99 up to 150 qubits. Furthermore, the linear scaling of entanglement entropy with system size suggests that the circuit is challenging to simulate classically using tensor networks. We also demonstrate hardware runs on IBM's device for 40, 60, and 80 qubits, and obtain solutions compatible with that from simulated annealing.
format Preprint
id arxiv_https___arxiv_org_abs_2505_22924
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Optimizing QUBO on a quantum computer by mimicking imaginary time evolution
Chai, Yahui
Di Tucci, Alice
Quantum Physics
We propose a hybrid quantum-classical algorithm for solving QUBO problems using an Imaginary Time Evolution-Mimicking Circuit (ITEMC). The circuit parameters are optimized to closely mimic imaginary time evolution, using only single- and two-qubit expectation values. This significantly reduces the measurement overhead by avoiding full energy evaluation. By updating the initial state based on results from last step iteratively, the algorithm quickly converges to the low-energy solutions. With a pre-sorting step that optimizes quantum gate ordering based on QUBO coefficients, the convergence is further improved. Our classical simulations achieve approximation ratios above 0.99 up to 150 qubits. Furthermore, the linear scaling of entanglement entropy with system size suggests that the circuit is challenging to simulate classically using tensor networks. We also demonstrate hardware runs on IBM's device for 40, 60, and 80 qubits, and obtain solutions compatible with that from simulated annealing.
title Optimizing QUBO on a quantum computer by mimicking imaginary time evolution
topic Quantum Physics
url https://arxiv.org/abs/2505.22924