Tensor Product Scheme for Computing Bound States of the Quantum Mechanical Three-Body Problem

TL;DR

This paper introduces a tensor-based computational method for efficiently calculating bound states and energies in low-dimensional quantum three-body problems, significantly improving speed and accuracy over existing methods.

Contribution

The authors develop a novel tensor product scheme combined with a specialized preconditioner and parallel implementation for solving three-body quantum problems in low dimensions.

Findings

Faster computation of three-body energies compared to existing methods.

High accuracy in calculating bound states in one and two dimensions.

Applicable to ultracold atomic gases and quantum sensors.

Abstract

We develop a computationally and numerically efficient method to calculate binding energies and corresponding wave functions of quantum mechanical three-body problems in low dimensions. Our approach exploits the tensor structure of the multidimensional stationary Schr\"odinger equation, being expressed as a discretized linear eigenvalue problem. In one spatial dimension, we solve the three-body problem with the help of iterative methods. Here the application of the Hamiltonian operator is represented by dense matrix-matrix products. In combination with a newly-designed preconditioner for the Jacobi-Davidson QR, our highly accurate tensor method offers a significantly faster computation of three-body energies and bound states than other existing approaches. For the two-dimensional case, we additionally make use of a hybrid distributed/shared memory parallel implementation to calculate the corresponding three-body energies. Our novel method is of high relevance for the analysis of few-body systems and their universal behavior, which is only governed by the particle masses, overall symmetries, and the spatial dimensionality. Our results have straightforward applications for ultracold atomic gases that are widespread and nowadays utilized in quantum sensors.