Scalable simulation of non-Markovian quantum transport by stochastic-phase bath reduction
Abstract
Accurate simulations of non-Markovian quantum transport remain limited to small systems, and a key bottleneck is that each system site requires an independent set of quantum bath orbitals. We introduce the Stochastic Phase Algorithm (SPA), which replaces the independent local Gaussian baths in single-quasiparticle Holstein models by R shared quantum baths with stochastic site-dependent phases. We prove that phase averaging reproduces the target two-point bath correlation matrix for every R, while increasing R systematically suppresses errors from higher-order cross-site correlations. We obtain a fixed-time O(R−1) trace-norm error bound with a prefactor independent of system size and connectivity. This spatial compression applies directly to unitary baths and can be combined with coupled-Lindblad spectral compression [Phys. Rev. Lett. 136, 090403 (2026)], which represents each shared environment by a very small number of coupled, damped quantum modes fitted to its thermal bath correlation over the simulation window. Numerically, SPA converges against direct unitary benchmarks on a 3×3 lattice, enables full-state-vector quantum-bath dynamics on a 100×100 lattice, and, with R=1, closely reproduces near exact benchmarks for exciton populations in bacteriochlorophyll aggregates and carrier mobility in rubrene.
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BibTeX
@misc{huang2026scalable,
title = {{Scalable simulation of non-Markovian quantum transport by stochastic-phase bath reduction}},
author = {Zhen Huang and Lin Lin and Pinchen Xie},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.28318},
eprint = {2609.28318},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.28318},
}
RIS
TY - UNPB
TI - Scalable simulation of non-Markovian quantum transport by stochastic-phase bath reduction
AU - Zhen Huang
AU - Lin Lin
AU - Pinchen Xie
PY - 2026
DA - 2026/09/23
PB - arXiv
DO - 10.48550/arxiv.2609.28318
UR - https://arxiv.org/abs/2609.28318
AB - Accurate simulations of non-Markovian quantum transport remain limited to small systems, and a key bottleneck is that each system site requires an independent set of quantum bath orbitals. We introduce the Stochastic Phase Algorithm (SPA), which replaces the independent local Gaussian baths in single-quasiparticle Holstein models by R shared quantum baths with stochastic site-dependent phases. We prove that phase averaging reproduces the target two-point bath correlation matrix for every R, while increasing R systematically suppresses errors from higher-order cross-site correlations. We obtain a fixed-time O(R^−1) trace-norm error bound with a prefactor independent of system size and connectivity. This spatial compression applies directly to unitary baths and can be combined with coupled-Lindblad spectral compression [Phys. Rev. Lett. 136, 090403 (2026)], which represents each shared environment by a very small number of coupled, damped quantum modes fitted to its thermal bath correlation over the simulation window. Numerically, SPA converges against direct unitary benchmarks on a 3×3 lattice, enables full-state-vector quantum-bath dynamics on a 100×100 lattice, and, with R=1, closely reproduces near exact benchmarks for exciton populations in bacteriochlorophyll aggregates and carrier mobility in rubrene.
ER -