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Volume 39, Issue 6
The Random Batch Method for $N$-Body Quantum Dynamics

François Golse, Shi Jin & Thierry Paul

J. Comp. Math., 39 (2021), pp. 897-922.

Published online: 2021-10

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  • Abstract

This paper discusses a numerical method for computing the evolution of large interacting system of quantum particles. The idea of the random batch method is to replace the total interaction of each particle with the $N-1$ other particles by the interaction with $p\ll N$ particles chosen at random at each time step, multiplied by $(N-1)/p$. This reduces the computational cost of computing the interaction potential per time step from $O(N^2)$ to $O(N)$. For simplicity, we consider only in this work the case $p=1$ — in other words, we assume that $N$ is even, and that at each time step, the $N$ particles are organized in $N/2$ pairs, with a random reshuffling of the pairs at the beginning of each time step. We obtain a convergence estimate for the Wigner transform of the single-particle reduced density matrix of the particle system at time $t$ that is both uniform in $N>1$ and independent of the Planck constant $\hbar$. The key idea is to use a new type of distance on the set of quantum states that is reminiscent of the Wasserstein distance of exponent $1$ (or Monge-Kantorovich-Rubinstein distance) on the set of Borel probability measures on $\mathbf{R}^d$ used in the context of optimal transport.

  • AMS Subject Headings

82C10, 82C22 (65M75)

  • Copyright

COPYRIGHT: © Global Science Press

  • Email address

francois.golse@polytechnique.edu (François Golse)

shijin-m@sjtu.edu.cn (Shi Jin)

thierry.paul@upmc.fr (Thierry Paul)

  • BibTex
  • RIS
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@Article{JCM-39-897, author = {Golse , FrançoisJin , Shi and Paul , Thierry}, title = {The Random Batch Method for $N$-Body Quantum Dynamics}, journal = {Journal of Computational Mathematics}, year = {2021}, volume = {39}, number = {6}, pages = {897--922}, abstract = {

This paper discusses a numerical method for computing the evolution of large interacting system of quantum particles. The idea of the random batch method is to replace the total interaction of each particle with the $N-1$ other particles by the interaction with $p\ll N$ particles chosen at random at each time step, multiplied by $(N-1)/p$. This reduces the computational cost of computing the interaction potential per time step from $O(N^2)$ to $O(N)$. For simplicity, we consider only in this work the case $p=1$ — in other words, we assume that $N$ is even, and that at each time step, the $N$ particles are organized in $N/2$ pairs, with a random reshuffling of the pairs at the beginning of each time step. We obtain a convergence estimate for the Wigner transform of the single-particle reduced density matrix of the particle system at time $t$ that is both uniform in $N>1$ and independent of the Planck constant $\hbar$. The key idea is to use a new type of distance on the set of quantum states that is reminiscent of the Wasserstein distance of exponent $1$ (or Monge-Kantorovich-Rubinstein distance) on the set of Borel probability measures on $\mathbf{R}^d$ used in the context of optimal transport.

}, issn = {1991-7139}, doi = {https://doi.org/10.4208/jcm.2107-m2020-0306}, url = {http://global-sci.org/intro/article_detail/jcm/19946.html} }
TY - JOUR T1 - The Random Batch Method for $N$-Body Quantum Dynamics AU - Golse , François AU - Jin , Shi AU - Paul , Thierry JO - Journal of Computational Mathematics VL - 6 SP - 897 EP - 922 PY - 2021 DA - 2021/10 SN - 39 DO - http://doi.org/10.4208/jcm.2107-m2020-0306 UR - https://global-sci.org/intro/article_detail/jcm/19946.html KW - Time-dependent Schrödinger equations, Random batch method, Mean-field limit, Wasserstein distance. AB -

This paper discusses a numerical method for computing the evolution of large interacting system of quantum particles. The idea of the random batch method is to replace the total interaction of each particle with the $N-1$ other particles by the interaction with $p\ll N$ particles chosen at random at each time step, multiplied by $(N-1)/p$. This reduces the computational cost of computing the interaction potential per time step from $O(N^2)$ to $O(N)$. For simplicity, we consider only in this work the case $p=1$ — in other words, we assume that $N$ is even, and that at each time step, the $N$ particles are organized in $N/2$ pairs, with a random reshuffling of the pairs at the beginning of each time step. We obtain a convergence estimate for the Wigner transform of the single-particle reduced density matrix of the particle system at time $t$ that is both uniform in $N>1$ and independent of the Planck constant $\hbar$. The key idea is to use a new type of distance on the set of quantum states that is reminiscent of the Wasserstein distance of exponent $1$ (or Monge-Kantorovich-Rubinstein distance) on the set of Borel probability measures on $\mathbf{R}^d$ used in the context of optimal transport.

François Golse, Shi Jin & Thierry Paul. (2021). The Random Batch Method for $N$-Body Quantum Dynamics. Journal of Computational Mathematics. 39 (6). 897-922. doi:10.4208/jcm.2107-m2020-0306
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