Adaptive measurement strategy for quantum subspace methods
Estimation of physical observables for unknown quantum states is an important problem that underlies a wide range of fields, including quantum information processing, quantum physics, and quantum chemistry. In the context of quantum computation, in particular, existing studies have mainly focused on...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
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IOP Publishing
2024-01-01
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| Series: | New Journal of Physics |
| Subjects: | |
| Online Access: | https://doi.org/10.1088/1367-2630/ad2c3b |
| _version_ | 1797258378997661696 |
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| author | Yuma Nakamura Yoshichika Yano Nobuyuki Yoshioka |
| author_facet | Yuma Nakamura Yoshichika Yano Nobuyuki Yoshioka |
| author_sort | Yuma Nakamura |
| collection | DOAJ |
| description | Estimation of physical observables for unknown quantum states is an important problem that underlies a wide range of fields, including quantum information processing, quantum physics, and quantum chemistry. In the context of quantum computation, in particular, existing studies have mainly focused on holistic state tomography or estimation on specific observables with known classical descriptions, while this lacks the important class of problems where the estimation target itself relies on the measurement outcome. In this work, we propose an adaptive measurement optimization method that is useful for the quantum subspace methods, namely the variational simulation methods that utilize classical postprocessing on measurement outcomes. The proposed method first determines the measurement protocol for classically simulatable states, and then adaptively updates the protocol of quantum subspace expansion (QSE) according to the quantum measurement result. As a numerical demonstration, we have shown for excited-state simulation of molecules that (i) we are able to reduce the number of measurements by an order of magnitude by constructing an appropriate measurement strategy (ii) the adaptive iteration converges successfully even for a strongly correlated molecule of H _4 . Our work reveals that the potential of the QSE method can be empowered by elaborated measurement protocols, and opens a path to further pursue efficient quantum measurement techniques in practical computations. |
| first_indexed | 2024-04-24T22:52:35Z |
| format | Article |
| id | doaj.art-69bb2780b7e14ed1b03d65f8a2b09bdb |
| institution | Directory Open Access Journal |
| issn | 1367-2630 |
| language | English |
| last_indexed | 2024-04-24T22:52:35Z |
| publishDate | 2024-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | New Journal of Physics |
| spelling | doaj.art-69bb2780b7e14ed1b03d65f8a2b09bdb2024-03-18T10:26:13ZengIOP PublishingNew Journal of Physics1367-26302024-01-0126303302810.1088/1367-2630/ad2c3bAdaptive measurement strategy for quantum subspace methodsYuma Nakamura0https://orcid.org/0000-0002-4860-380XYoshichika Yano1Nobuyuki Yoshioka2https://orcid.org/0000-0001-6094-8635Healthcare & Life Science, IBM Japan , 19-21 Nihonbashi Hakozaki-cho, Chuo-ku, Tokyo 103-8510, JapanDepartment of Applied Physics, University of Tokyo , 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, JapanDepartment of Applied Physics, University of Tokyo , 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan; Theoretical Quantum Physics Laboratory, RIKEN Cluster for Pioneering Research (CPR) , Wako-shi, Saitama 351-0198, Japan; JST, PRESTO , 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, JapanEstimation of physical observables for unknown quantum states is an important problem that underlies a wide range of fields, including quantum information processing, quantum physics, and quantum chemistry. In the context of quantum computation, in particular, existing studies have mainly focused on holistic state tomography or estimation on specific observables with known classical descriptions, while this lacks the important class of problems where the estimation target itself relies on the measurement outcome. In this work, we propose an adaptive measurement optimization method that is useful for the quantum subspace methods, namely the variational simulation methods that utilize classical postprocessing on measurement outcomes. The proposed method first determines the measurement protocol for classically simulatable states, and then adaptively updates the protocol of quantum subspace expansion (QSE) according to the quantum measurement result. As a numerical demonstration, we have shown for excited-state simulation of molecules that (i) we are able to reduce the number of measurements by an order of magnitude by constructing an appropriate measurement strategy (ii) the adaptive iteration converges successfully even for a strongly correlated molecule of H _4 . Our work reveals that the potential of the QSE method can be empowered by elaborated measurement protocols, and opens a path to further pursue efficient quantum measurement techniques in practical computations.https://doi.org/10.1088/1367-2630/ad2c3bquantum computingobservable estimationquantum subspace expansionclassical shadowspartial tomography |
| spellingShingle | Yuma Nakamura Yoshichika Yano Nobuyuki Yoshioka Adaptive measurement strategy for quantum subspace methods New Journal of Physics quantum computing observable estimation quantum subspace expansion classical shadows partial tomography |
| title | Adaptive measurement strategy for quantum subspace methods |
| title_full | Adaptive measurement strategy for quantum subspace methods |
| title_fullStr | Adaptive measurement strategy for quantum subspace methods |
| title_full_unstemmed | Adaptive measurement strategy for quantum subspace methods |
| title_short | Adaptive measurement strategy for quantum subspace methods |
| title_sort | adaptive measurement strategy for quantum subspace methods |
| topic | quantum computing observable estimation quantum subspace expansion classical shadows partial tomography |
| url | https://doi.org/10.1088/1367-2630/ad2c3b |
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