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arXiv:2511.13256 · Physics Letters A

Depth Optimization of Ansatz Circuits for Variational Quantum Algorithms

Spyros Tserkis, Muhammad Umer, Dimitris G. Angelakis

quant-phSubmitted Nov 17, 2025• Announced Nov 18, 2025• 0 citations
v1 · Nov 17, 2025v2 · Mar 23, 2026
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Abstract

The increasing depth of quantum circuits presents a major limitation for the execution of quantum algorithms, as the limited coherence time of physical qubits leads to noise that manifests as errors during computation. In this work, we focus on circuits relevant to variational quantum algorithms and demonstrate that their depth can be reduced by introducing additional qubits, mid-circuit measurements, and classically controlled operations. As an illustrative example, we consider nonlinear dynamics governed by the one-dimensional Burgers' equation, which has broad applications in computational fluid dynamics. In particular, we show that the proposed non-unitary quantum circuits can efficiently represent fluid flow configurations in both laminar and turbulent regimes. Furthermore, we demonstrate that, when noise is taken into account, these circuits are advantageous in regimes where two-qubit gate error rates are relatively low compared to idling error rates.

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9 pages, 7 figures

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