Characterizing randomness in parameterized quantum circuits through expressibility and average entanglement

Fuente: arXiv
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Auteurs principaux: Correr, Guilherme Ilário, Medina, Ivan, Azado, Pedro C., Drinko, Alexandre, Soares-Pinto, Diogo O.
Format: Preprint
Publié: 2024
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author Correr, Guilherme Ilário
Medina, Ivan
Azado, Pedro C.
Drinko, Alexandre
Soares-Pinto, Diogo O.
author_facet Correr, Guilherme Ilário
Medina, Ivan
Azado, Pedro C.
Drinko, Alexandre
Soares-Pinto, Diogo O.
contents While scalable error correction schemes and fault tolerant quantum computing seem not to be universally accessible in the near sight, the efforts of many researchers have been directed to the exploration of the contemporary available quantum hardware. Due to these limitations, the depth and dimension of the possible quantum circuits are restricted. This motivates the study of circuits with parameterized operations that can be classically optimized in hybrid methods as variational quantum algorithms (VQAs), enabling the reduction of circuit depth and size. The characteristics of these Parameterized Quantum Circuits (PQCs) are still not fully understood outside the scope of their principal application, motivating the study of their intrinsic properties. In this work, we analyse the generation of random states in PQCs under restrictions on the qubits connectivities, justified by different quantum computer architectures. We apply the expressibility quantifier and the average entanglement as diagnostics for the characteristics of the generated states and classify the circuits depending on the topology of the quantum computer where they can be implemented. As a function of the number of layers and qubits, circuits following a Ring topology will have the highest entanglement and expressibility values, followed by Linear/All-to-all almost together and the Star topology. In addition to the characterization of the differences between the entanglement and expressibility of these circuits, we also place a connection between how steep is the increase on the uniformity of the distribution of the generated states and the generation of entanglement. Circuits generating average and standard deviation for entanglement closer to values obtained with the truly uniformly random ensemble of unitaries present a steeper evolution when compared to others.
format Preprint
id arxiv_https___arxiv_org_abs_2405_02265
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Characterizing randomness in parameterized quantum circuits through expressibility and average entanglement
Correr, Guilherme Ilário
Medina, Ivan
Azado, Pedro C.
Drinko, Alexandre
Soares-Pinto, Diogo O.
Quantum Physics
While scalable error correction schemes and fault tolerant quantum computing seem not to be universally accessible in the near sight, the efforts of many researchers have been directed to the exploration of the contemporary available quantum hardware. Due to these limitations, the depth and dimension of the possible quantum circuits are restricted. This motivates the study of circuits with parameterized operations that can be classically optimized in hybrid methods as variational quantum algorithms (VQAs), enabling the reduction of circuit depth and size. The characteristics of these Parameterized Quantum Circuits (PQCs) are still not fully understood outside the scope of their principal application, motivating the study of their intrinsic properties. In this work, we analyse the generation of random states in PQCs under restrictions on the qubits connectivities, justified by different quantum computer architectures. We apply the expressibility quantifier and the average entanglement as diagnostics for the characteristics of the generated states and classify the circuits depending on the topology of the quantum computer where they can be implemented. As a function of the number of layers and qubits, circuits following a Ring topology will have the highest entanglement and expressibility values, followed by Linear/All-to-all almost together and the Star topology. In addition to the characterization of the differences between the entanglement and expressibility of these circuits, we also place a connection between how steep is the increase on the uniformity of the distribution of the generated states and the generation of entanglement. Circuits generating average and standard deviation for entanglement closer to values obtained with the truly uniformly random ensemble of unitaries present a steeper evolution when compared to others.
title Characterizing randomness in parameterized quantum circuits through expressibility and average entanglement
topic Quantum Physics
url https://arxiv.org/abs/2405.02265