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It may provide new answers to difficult questions, such as whether nonlinear measurements can compensate for linear, constrained control. Here we show that reinforcement learning can successfully discover such feedback strategies, without prior knowledge. We illustrate this for state preparation in a cavity subject to quantum-non-demolition detection of photon number, with a simple linear drive as control. Fock states can be produced and stabilized at very high fidelity. It is even possible to reach superposition states, provided the measurement rates for different Fock states can be controlled as well.<\/jats:p>","DOI":"10.22331\/q-2022-06-28-747","type":"journal-article","created":{"date-parts":[[2022,7,4]],"date-time":"2022-07-04T14:17:11Z","timestamp":1656944231000},"page":"747","update-policy":"https:\/\/doi.org\/10.22331\/q-crossmark-policy-page","source":"Crossref","is-referenced-by-count":63,"title":["Deep Reinforcement Learning for Quantum State Preparation with Weak Nonlinear Measurements"],"prefix":"10.22331","volume":"6","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-7632-6141","authenticated-orcid":false,"given":"Riccardo","family":"Porotti","sequence":"first","affiliation":[{"name":"Max Planck Institute for the Science of Light, Erlangen, Germany"},{"name":"Department of Physics, Friedrich-Alexander Universit\u00e4t Erlangen-N\u00fcrnberg, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Antoine","family":"Essig","sequence":"additional","affiliation":[{"name":"Univ Lyon, ENS de Lyon, CNRS, Laboratoire de Physique,F-69342 Lyon, France"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9848-3658","authenticated-orcid":false,"given":"Benjamin","family":"Huard","sequence":"additional","affiliation":[{"name":"Univ Lyon, ENS de Lyon, CNRS, Laboratoire de Physique,F-69342 Lyon, France"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4566-1753","authenticated-orcid":false,"given":"Florian","family":"Marquardt","sequence":"additional","affiliation":[{"name":"Max Planck Institute for the Science of Light, Erlangen, Germany"},{"name":"Department of Physics, Friedrich-Alexander Universit\u00e4t Erlangen-N\u00fcrnberg, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"9598","published-online":{"date-parts":[[2022,6,28]]},"reference":[{"key":"0","doi-asserted-by":"publisher","unstructured":"Navin Khaneja, Timo Reiss, Cindie Kehlet, Thomas Schulte-Herbr\u00fcggen, and Steffen J. 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