Efficient experimental characterization of quantum processes via compressed sensing on an NMR quantum processor

Fuente: arXiv
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Auteurs principaux: Gaikwad, Akshay, Arvind, Dorai, Kavita
Format: Preprint
Publié: 2021
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author Gaikwad, Akshay
Arvind
Dorai, Kavita
author_facet Gaikwad, Akshay
Arvind
Dorai, Kavita
contents We employ the compressed sensing (CS) algorithm and a heavily reduced data set to experimentally perform true quantum process tomography (QPT) on an NMR quantum processor. We obtain the estimate of the process matrix $χ$ corresponding to various two- and three-qubit quantum gates with a high fidelity. The CS algorithm is implemented using two different operator bases, namely, the standard Pauli basis and the Pauli-error basis. We experimentally demonstrate that the performance of the CS algorithm is significantly better in the Pauli-error basis, where the constructed $χ$ matrix is maximally sparse. We compare the standard least square (LS) optimization QPT method with the CS-QPT method and observe that, provided an appropriate basis is chosen, the CS-QPT method performs significantly better as compared to the LS-QPT method. In all the cases considered, we obtained experimental fidelities greater than 0.9 from a reduced data set, which was approximately five to six times smaller in size than a full data set. We also experimentally characterized the reduced dynamics of a two-qubit subsystem embedded in a three-qubit system, and used the CS-QPT method to characterize processes corresponding to the evolution of two-qubit states under various $J$-coupling interactions.
format Preprint
id arxiv_https___arxiv_org_abs_2109_13189
institution arXiv
publishDate 2021
record_format arxiv
spellingShingle Efficient experimental characterization of quantum processes via compressed sensing on an NMR quantum processor
Gaikwad, Akshay
Arvind
Dorai, Kavita
Quantum Physics
We employ the compressed sensing (CS) algorithm and a heavily reduced data set to experimentally perform true quantum process tomography (QPT) on an NMR quantum processor. We obtain the estimate of the process matrix $χ$ corresponding to various two- and three-qubit quantum gates with a high fidelity. The CS algorithm is implemented using two different operator bases, namely, the standard Pauli basis and the Pauli-error basis. We experimentally demonstrate that the performance of the CS algorithm is significantly better in the Pauli-error basis, where the constructed $χ$ matrix is maximally sparse. We compare the standard least square (LS) optimization QPT method with the CS-QPT method and observe that, provided an appropriate basis is chosen, the CS-QPT method performs significantly better as compared to the LS-QPT method. In all the cases considered, we obtained experimental fidelities greater than 0.9 from a reduced data set, which was approximately five to six times smaller in size than a full data set. We also experimentally characterized the reduced dynamics of a two-qubit subsystem embedded in a three-qubit system, and used the CS-QPT method to characterize processes corresponding to the evolution of two-qubit states under various $J$-coupling interactions.
title Efficient experimental characterization of quantum processes via compressed sensing on an NMR quantum processor
topic Quantum Physics
url https://arxiv.org/abs/2109.13189