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Main Authors: Ye, Bin, Chen, Ruitao, Yin, Lei
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2604.03662
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author Ye, Bin
Chen, Ruitao
Yin, Lei
author_facet Ye, Bin
Chen, Ruitao
Yin, Lei
contents We present a unified quantum-mechanical derivation of the Wallis formula from two solvable radial systems: the circular states of the three-dimensional isotropic harmonic oscillator and the lowest-radial-branch states of the planar Fock--Darwin problem, including the lowest Landau level sector. In both cases, the radial probability density has the exact form $P(r)\propto r^νe^{-λr^2}$, which yields the scale-independent reciprocal observable $Q=\langle r\rangle\langle r^{-1}\rangle$. The two systems realize the even and odd half-integer Gamma-function branches of the same moment formula, so that the associated finite Wallis partial products are determined by $Q$ in one case and by $Q^{-1}$ in the other. In the large-angular-momentum regime, the corresponding states become localized on a thin spherical shell or a narrow annulus, with vanishing relative radial width, so that $Q\to1$ and both finite-product representations reduce to the Wallis formula for $π$.
format Preprint
id arxiv_https___arxiv_org_abs_2604_03662
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Quantum Realization of the Wallis Formula
Ye, Bin
Chen, Ruitao
Yin, Lei
Quantum Physics
High Energy Physics - Theory
We present a unified quantum-mechanical derivation of the Wallis formula from two solvable radial systems: the circular states of the three-dimensional isotropic harmonic oscillator and the lowest-radial-branch states of the planar Fock--Darwin problem, including the lowest Landau level sector. In both cases, the radial probability density has the exact form $P(r)\propto r^νe^{-λr^2}$, which yields the scale-independent reciprocal observable $Q=\langle r\rangle\langle r^{-1}\rangle$. The two systems realize the even and odd half-integer Gamma-function branches of the same moment formula, so that the associated finite Wallis partial products are determined by $Q$ in one case and by $Q^{-1}$ in the other. In the large-angular-momentum regime, the corresponding states become localized on a thin spherical shell or a narrow annulus, with vanishing relative radial width, so that $Q\to1$ and both finite-product representations reduce to the Wallis formula for $π$.
title Quantum Realization of the Wallis Formula
topic Quantum Physics
High Energy Physics - Theory
url https://arxiv.org/abs/2604.03662