--- _id: '11471' abstract: - lang: eng text: 'Variational quantum algorithms are promising algorithms for achieving quantum advantage on nearterm devices. The quantum hardware is used to implement a variational wave function and measure observables, whereas the classical computer is used to store and update the variational parameters. The optimization landscape of expressive variational ansätze is however dominated by large regions in parameter space, known as barren plateaus, with vanishing gradients, which prevents efficient optimization. In this work we propose a general algorithm to avoid barren plateaus in the initialization and throughout the optimization. To this end we define a notion of weak barren plateaus (WBPs) based on the entropies of local reduced density matrices. The presence of WBPs can be efficiently quantified using recently introduced shadow tomography of the quantum state with a classical computer. We demonstrate that avoidance of WBPs suffices to ensure sizable gradients in the initialization. In addition, we demonstrate that decreasing the gradient step size, guided by the entropies allows WBPs to be avoided during the optimization process. This paves the way for efficient barren plateau-free optimization on near-term devices. ' acknowledgement: "We thank Marco Cerezo, Zoe Holmes, and Nicholas Hunter-Jones for fruitful discussion and valuable feedback. We also acknowledge Adam Smith, Johannes Jakob Meyer, and Victor V. Albert for comments on the paper. The simulations were performed in the Julia programming\r\nlanguage [65] using the Yao module [66]. S.H.S., R.A.M., A.A.M. and M.S. acknowledge support by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (Grant Agreement No. 850899)." article_number: '020365' article_processing_charge: No article_type: original author: - first_name: Stefan full_name: Sack, Stefan id: dd622248-f6e0-11ea-865d-ce382a1c81a5 last_name: Sack orcid: 0000-0001-5400-8508 - first_name: Raimel A full_name: Medina Ramos, Raimel A id: CE680B90-D85A-11E9-B684-C920E6697425 last_name: Medina Ramos orcid: 0000-0002-5383-2869 - first_name: Alexios full_name: Michailidis, Alexios id: 36EBAD38-F248-11E8-B48F-1D18A9856A87 last_name: Michailidis orcid: 0000-0002-8443-1064 - first_name: Richard full_name: Kueng, Richard last_name: Kueng - first_name: Maksym full_name: Serbyn, Maksym id: 47809E7E-F248-11E8-B48F-1D18A9856A87 last_name: Serbyn orcid: 0000-0002-2399-5827 citation: ama: Sack S, Medina Ramos RA, Michailidis A, Kueng R, Serbyn M. Avoiding barren plateaus using classical shadows. PRX Quantum. 2022;3(2). doi:10.1103/prxquantum.3.020365 apa: Sack, S., Medina Ramos, R. A., Michailidis, A., Kueng, R., & Serbyn, M. (2022). Avoiding barren plateaus using classical shadows. PRX Quantum. American Physical Society. https://doi.org/10.1103/prxquantum.3.020365 chicago: Sack, Stefan, Raimel A Medina Ramos, Alexios Michailidis, Richard Kueng, and Maksym Serbyn. “Avoiding Barren Plateaus Using Classical Shadows.” PRX Quantum. American Physical Society, 2022. https://doi.org/10.1103/prxquantum.3.020365. ieee: S. Sack, R. A. Medina Ramos, A. Michailidis, R. Kueng, and M. Serbyn, “Avoiding barren plateaus using classical shadows,” PRX Quantum, vol. 3, no. 2. American Physical Society, 2022. ista: Sack S, Medina Ramos RA, Michailidis A, Kueng R, Serbyn M. 2022. Avoiding barren plateaus using classical shadows. PRX Quantum. 3(2), 020365. mla: Sack, Stefan, et al. “Avoiding Barren Plateaus Using Classical Shadows.” PRX Quantum, vol. 3, no. 2, 020365, American Physical Society, 2022, doi:10.1103/prxquantum.3.020365. short: S. Sack, R.A. Medina Ramos, A. Michailidis, R. Kueng, M. Serbyn, PRX Quantum 3 (2022). date_created: 2022-06-29T20:21:32Z date_published: 2022-06-29T00:00:00Z date_updated: 2023-12-13T14:47:24Z day: '29' ddc: - '530' department: - _id: MaSe doi: 10.1103/prxquantum.3.020365 ec_funded: 1 external_id: arxiv: - '2201.08194' isi: - '000822564300001' file: - access_level: open_access checksum: a7706b28d24a0e32a55ea04b82a2df43 content_type: application/pdf creator: dernst date_created: 2022-06-30T07:14:48Z date_updated: 2022-06-30T07:14:48Z file_id: '11472' file_name: 2022_PRXQuantum_Sack.pdf file_size: 4231591 relation: main_file success: 1 file_date_updated: 2022-06-30T07:14:48Z has_accepted_license: '1' intvolume: ' 3' isi: 1 issue: '2' keyword: - General Medicine language: - iso: eng license: https://creativecommons.org/licenses/by/4.0/ month: '06' oa: 1 oa_version: Published Version project: - _id: 23841C26-32DE-11EA-91FC-C7463DDC885E call_identifier: H2020 grant_number: '850899' name: 'Non-Ergodic Quantum Matter: Universality, Dynamics and Control' publication: PRX Quantum publication_identifier: issn: - 2691-3399 publication_status: published publisher: American Physical Society quality_controlled: '1' related_material: record: - id: '14622' relation: dissertation_contains status: public status: public title: Avoiding barren plateaus using classical shadows tmp: image: /images/cc_by.png legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0) short: CC BY (4.0) type: journal_article user_id: 4359f0d1-fa6c-11eb-b949-802e58b17ae8 volume: 3 year: '2022' ...