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DOE OSTI · 1853072

Constructing tensor network influence functionals for general quantum dynamics

Ye, Erika·Chan, Garnet Kin-Lic
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Abstract

Here, we describe an iterative formalism to compute influence functionals that describe the general quantum dynamics of a subsystem beyond the assumption of linear coupling to a quadratic bath. We use a space-time tensor network representation of the influence functional and investigate its approximability in terms of its bond dimension and time-like entanglement in the tensor network description. We study two numerical models, the spin-boson model and a model of interacting hard-core bosons in a 1D harmonic trap. We find that the influence functional and the intermediates involved in its construction can be efficiently approximated by low bond dimension tensor networks in certain dynamical regimes, which allows the quantum dynamics to be accurately computed for longer times than with direct time evolution methods. However, as one iteratively integrates out the bath, the correlations in the influence functional can first increase before decreasing, indicating that the final compressibility of the influence functional is achieved via non-trivial cancellation.

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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICSQuantum entanglementcomplex systems theorydynamical correlationmatrix product statenumerical methodsquantum mechanical principlesspin-boson modeltensor network theory

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Ye, Erika, Chan, Garnet Kin-Lic. 2021-07-26. Constructing tensor network influence functionals for general quantum dynamics. https://doi.org/10.1063/5.0047260

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