Emergence of noise-induced barren plateaus in arbitrary layered noise models

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Hauptverfasser: Schumann, Marco, Wilhelm, Frank K., Ciani, Alessandro
Format: Preprint
Veröffentlicht: 2023
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author Schumann, Marco
Wilhelm, Frank K.
Ciani, Alessandro
author_facet Schumann, Marco
Wilhelm, Frank K.
Ciani, Alessandro
contents In variational quantum algorithms the parameters of a parameterized quantum circuit are optimized in order to minimize a cost function that encodes the solution of the problem. The barren plateau phenomenon manifests as an exponentially vanishing dependence of the cost function with respect to the variational parameters, and thus hampers the optimization process. We discuss how, and in which sense, the phenomenon of noise-induced barren plateaus emerges in parameterized quantum circuits with a layered noise model. Previous results have shown the existence of noise-induced barren plateaus in the presence of local Pauli noise [arXiv:2007.14384]. We extend these results analytically to arbitrary completely-positive trace preserving maps in two cases: 1) when a parameter-shift rule holds, 2) when the parameterized quantum circuit at each layer forms a unitary $2$-design. The second example shows how highly expressive unitaries give rise not only to standard barren plateaus [arXiv:1803.11173], but also to noise-induced ones. In the second part of the paper, we study numerically the emergence of noise-induced barren plateaus in QAOA circuits focusing on the case of MaxCut problems on $d$-regular graphs and amplitude damping noise.
format Preprint
id arxiv_https___arxiv_org_abs_2310_08405
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Emergence of noise-induced barren plateaus in arbitrary layered noise models
Schumann, Marco
Wilhelm, Frank K.
Ciani, Alessandro
Quantum Physics
In variational quantum algorithms the parameters of a parameterized quantum circuit are optimized in order to minimize a cost function that encodes the solution of the problem. The barren plateau phenomenon manifests as an exponentially vanishing dependence of the cost function with respect to the variational parameters, and thus hampers the optimization process. We discuss how, and in which sense, the phenomenon of noise-induced barren plateaus emerges in parameterized quantum circuits with a layered noise model. Previous results have shown the existence of noise-induced barren plateaus in the presence of local Pauli noise [arXiv:2007.14384]. We extend these results analytically to arbitrary completely-positive trace preserving maps in two cases: 1) when a parameter-shift rule holds, 2) when the parameterized quantum circuit at each layer forms a unitary $2$-design. The second example shows how highly expressive unitaries give rise not only to standard barren plateaus [arXiv:1803.11173], but also to noise-induced ones. In the second part of the paper, we study numerically the emergence of noise-induced barren plateaus in QAOA circuits focusing on the case of MaxCut problems on $d$-regular graphs and amplitude damping noise.
title Emergence of noise-induced barren plateaus in arbitrary layered noise models
topic Quantum Physics
url https://arxiv.org/abs/2310.08405