A1 Refereed original research article in a scientific journal

Learning to Measure: Adaptive Informationally Complete Generalized Measurements for Quantum Algorithms




AuthorsGarcía-Pérez Guillermo, Rossi Matteo AC, Sokolov Boris, Tacchino Francesco, Barkoutsos Panagiotis K, Mazzola Guglielmo, Tavernelli Ivano, Maniscalco Sabrina

PublisherAMER PHYSICAL SOC

Publication year2021

JournalPRX Quantum

Journal name in sourcePRX QUANTUM

Journal acronymPRX QUANTUM

Article numberARTN 040342

Volume2

Issue4

Number of pages17

DOIhttps://doi.org/10.1103/PRXQuantum.2.040342

Self-archived copy’s web addresshttps://research.utu.fi/converis/portal/detail/Publication/68194224


Abstract
Many prominent quantum computing algorithms with applications in fields such as chemistry and materials science require a large number of measurements, which represents an important roadblock for future real-world use cases. We introduce a novel approach to tackle this problem through an adaptive measurement scheme. We present an algorithm that optimizes informationally complete positive operator-valued measurements (POVMs) on the fly in order to minimize the statistical fluctuations in the estimation of relevant cost functions. We show its advantage by improving the efficiency of the variational quantum eigensolver in calculating ground-state energies of molecular Hamiltonians with extensive numerical simulations. Our results indicate that the proposed method is competitive with state-of-the-art measurement-reduction approaches in terms of efficiency. In addition, the informational completeness of the approach offers a crucial advantage, as the measurement data can be reused to infer other quantities of interest. We demonstrate the feasibility of this prospect by reusing ground-state energy-estimation data to perform high-fidelity reduced state tomography.

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