Sampling Groups of Pauli Operators to Enhance Direct Fidelity Estimation

Fuente: arXiv
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Autores principales: Barberà-Rodríguez, Júlia, Navarro, Mariana, Zambrano, Leonardo
Formato: Preprint
Publicado: 2025
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author Barberà-Rodríguez, Júlia
Navarro, Mariana
Zambrano, Leonardo
author_facet Barberà-Rodríguez, Júlia
Navarro, Mariana
Zambrano, Leonardo
contents Direct fidelity estimation is a protocol that estimates the fidelity between an experimental quantum state and a target pure state. By measuring the expectation values of Pauli operators selected through importance sampling, the method is exponentially faster than full quantum state tomography. We propose an enhanced direct fidelity estimation protocol that uses fewer copies of the experimental state by grouping Pauli operators before the sampling process. We derive analytical bounds on the measurement cost and estimator variance, showing improvements over the standard method. Numerical simulations validate our approach, demonstrating that for 8-qubit Haar-random states, our method achieves a one-third reduction in the required number of copies and reduces variance by an order of magnitude using only local measurements. These results underscore the potential of our protocol to enhance the efficiency of fidelity estimation in current quantum devices.
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id arxiv_https___arxiv_org_abs_2501_19228
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Sampling Groups of Pauli Operators to Enhance Direct Fidelity Estimation
Barberà-Rodríguez, Júlia
Navarro, Mariana
Zambrano, Leonardo
Quantum Physics
Direct fidelity estimation is a protocol that estimates the fidelity between an experimental quantum state and a target pure state. By measuring the expectation values of Pauli operators selected through importance sampling, the method is exponentially faster than full quantum state tomography. We propose an enhanced direct fidelity estimation protocol that uses fewer copies of the experimental state by grouping Pauli operators before the sampling process. We derive analytical bounds on the measurement cost and estimator variance, showing improvements over the standard method. Numerical simulations validate our approach, demonstrating that for 8-qubit Haar-random states, our method achieves a one-third reduction in the required number of copies and reduces variance by an order of magnitude using only local measurements. These results underscore the potential of our protocol to enhance the efficiency of fidelity estimation in current quantum devices.
title Sampling Groups of Pauli Operators to Enhance Direct Fidelity Estimation
topic Quantum Physics
url https://arxiv.org/abs/2501.19228