Symplectic Optimization on Gaussian States

Fuente: arXiv
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Hauptverfasser: Willby, Christopher, Hashizume, Tomohiro, Crain, Jason, Jaksch, Dieter
Format: Preprint
Veröffentlicht: 2026
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author Willby, Christopher
Hashizume, Tomohiro
Crain, Jason
Jaksch, Dieter
author_facet Willby, Christopher
Hashizume, Tomohiro
Crain, Jason
Jaksch, Dieter
contents Computing Gaussian ground states via variational optimization is challenging because the covariance matrices must satisfy the uncertainty principle, rendering constrained or Riemannian optimization costly, delicate, and thus difficult to scale, particularly in large and inhomogeneous systems. We introduce a symplectic optimization framework that addresses this challenge by parameterizing covariance matrices directly as positive-definite symplectic matrices using unit-triangular factorizations. This approach enforces all physical constraints exactly, yielding a globally unconstrained variational formulation of the bosonic ground-state problem. The unconstrained structure also naturally supports solution reuse across nearby Hamiltonians: warm-starting from previously optimized covariance matrices substantially reduces the number of optimization steps required for convergence in families of related configurations, as encountered in crystal lattices, molecular systems, and fluids. We demonstrate the method on weakly dipole-coupled lattices, recovering ground-state energies, covariance matrices, and spectral gaps accurately. The framework further provides a foundation for large-scale approximate treatments of weakly non-quadratic interactions and offers potential scaling advantages through tensor-network enhancements.
format Preprint
id arxiv_https___arxiv_org_abs_2601_20832
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Symplectic Optimization on Gaussian States
Willby, Christopher
Hashizume, Tomohiro
Crain, Jason
Jaksch, Dieter
Quantum Physics
Computing Gaussian ground states via variational optimization is challenging because the covariance matrices must satisfy the uncertainty principle, rendering constrained or Riemannian optimization costly, delicate, and thus difficult to scale, particularly in large and inhomogeneous systems. We introduce a symplectic optimization framework that addresses this challenge by parameterizing covariance matrices directly as positive-definite symplectic matrices using unit-triangular factorizations. This approach enforces all physical constraints exactly, yielding a globally unconstrained variational formulation of the bosonic ground-state problem. The unconstrained structure also naturally supports solution reuse across nearby Hamiltonians: warm-starting from previously optimized covariance matrices substantially reduces the number of optimization steps required for convergence in families of related configurations, as encountered in crystal lattices, molecular systems, and fluids. We demonstrate the method on weakly dipole-coupled lattices, recovering ground-state energies, covariance matrices, and spectral gaps accurately. The framework further provides a foundation for large-scale approximate treatments of weakly non-quadratic interactions and offers potential scaling advantages through tensor-network enhancements.
title Symplectic Optimization on Gaussian States
topic Quantum Physics
url https://arxiv.org/abs/2601.20832