Simulation of open quantum systems by automated compression of arbitrary environments
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Studies of the dynamics of open quantum systems are limited by the large Hilbert space of typical environments, which is too large to be treated exactly. In some cases, approximate descriptions of the system are possible, for example when the environment has a short memory time or only interacts weakly with the system. Accurate numerical methods exist but these are typically restricted to baths with Gaussian correlations, such as non-interacting bosons. Here we present a method for simulating open quantum systems with arbitrary environments that consist of a set of independent degrees of freedom. Our approach automatically reduces the large number of environmental degrees of freedom to those which are most relevant. Specifically, we show how the process tensor describing the effect of the environment can be iteratively constructed and compressed using matrix product state techniques. We demonstrate the power of this method by applying it to a range of open quantum systems, including with bosonic, fermionic, and spin environments. The versatility and efficiency of our automated compression of environments method provides a practical general-purpose tool for open quantum systems.
Cygorek , M , Cosacchi , M , Vagov , A , Axt , V M , Lovett , B W , Keeling , J & Gauger , E M 2022 , ' Simulation of open quantum systems by automated compression of arbitrary environments ' , Nature Physics , vol. 18 , no. 6 , pp. 662-668 . https://doi.org/10.1038/s41567-022-01544-9
Copyright © 2022 The Author(s), under exclusive licence to Springer Nature Limited. This work has been made available online in accordance with publisher policies or with permission. Permission for further reuse of this content should be sought from the publisher or the rights holder. This is the author created accepted manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at https://doi.org/10.1038/s41567-022-01544-9.
DescriptionFunding: M. Co. and V. M. A. are grateful for funding by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under project No. 419036043. A. V. acknowledges the support from the Russian Science Foundation under the Project 18-12-00429. M. Cy. and E. M. G. acknowledge funding from EPSRC grant no. EP/T01377X/1. B.W. L. and J. K. were supported by EPSRC grant no. EP/T014032/1.
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