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arXiv:2512.16168 · Physical Review A

Tunneling in double-well potentials within stochastic quantization: Application to ammonia inversion

Danilo F. Schafaschek, Giovani L. Vasconcelos, Antônio M. S. Macêdo

quant-phSubmitted Dec 18, 2025• Announced Dec 19, 2025• 0 citations
v1 · Dec 18, 2025v2 · Feb 26, 2026v3 · Apr 8, 2026
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Abstract

Stochastic quantization - introduced by Nelson in 1966 - describes quantum behavior as a conservative diffusion process in which a particle undergoes Brownian-like motion with a fluctuation amplitude set by Planck's constant. While it fully reproduces conventional quantum mechanics, this approach provides an alternative framework that enables the study of dynamical quantities not easily defined within the standard formulation. In the present work, stochastic quantization is employed to investigate tunneling-time statistics for bound states in double-well potentials. Using first-passage time theory within the stochastic quantization framework, both the mean tunneling time, $\barτ$, and the full probability distribution, $p(τ)$, are computed, and the theoretical predictions are validated through extensive numerical simulations of stochastic trajectories for the two potentials considered as representative cases. For the square double-well potential, analytical expressions for $\barτ$ are derived and show excellent agreement with simulations. In the high-barrier limit, the results reveal a direct relation between the stochastic-mechanical and quantum-mechanical tunneling times, expressed as $τ_{\mathrm{QM}} = (π/2)\barτ$, where $τ_{\mathrm{QM}}$ corresponds to half the oscillation period of the probability of finding the particle in either well. This relation is further confirmed for generic double-well systems through a WKB analysis. As a concrete application, the inversion dynamics of the ammonia molecule is analyzed, yielding an inversion frequency of approximately $24$ GHz, in close agreement with experimental observations. These results highlight the potential of stochastic quantization as a powerful and physically insightful framework for analyzing tunneling phenomena in quantum systems.

DOI
10.1103/zgjd-sp27
Comments
16 pages, 10 figures

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Stochastic quantization - introduced by Nelson in 1966 - describes quantum behavior as a conservative diffusion process in which a particle undergoes Brownian-like motion with a fluctuation amplitude set by Planck's constant. While it fully reproduces conventional quantum mechanics, this approach provides an alternative framework that enables the study of dynamical quantities not easily defined within the standard formulation. In the present work, stochastic quantization is employed to investigate tunneling-time statistics for bound states in double-well potentials. Using first-passage time theory within the stochastic quantization framework, both the mean tunneling time, τˉ\barττˉ, and the full probability distribution, p(τ)p(τ)p(τ), are computed, and the theoretical predictions are validated through extensive numerical simulations of stochastic trajectories for the two potentials considered as representative cases. For the square double-well potential, analytical expressions for τˉ\barττˉ are derived and show excellent agreement with simulations. In the high-barrier limit, the results reveal a direct relation between the stochastic-mechanical and quantum-mechanical tunneling times, expressed as τQM=(π/2)τˉτ_{\mathrm{QM}} = (π/2)\barττQM​=(π/2)τˉ, where τQMτ_{\mathrm{QM}}τQM​ corresponds to half the oscillation period of the probability of finding the particle in either well. This relation is further confirmed for generic double-well systems through a WKB analysis. As a concrete application, the inversion dynamics of the ammonia molecule is analyzed, yielding an inversion frequency of approximately 242424 GHz, in close agreement with experimental observations. These results highlight the potential of stochastic quantization as a powerful and physically insightful framework for analyzing tunneling phenomena in quantum systems.
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The problem of tunneling time associated with the passage of a particle through a tunneling barrier seems very simple. But it turns out to be very deceptive by the lack of a time operator and there is no clear consensus about simple expression for the tunneling time. In this paper we evaluate the tunneling time based on Nelson's quantum stochastic process approach. This approach describes the motion of a particle by a stochastic differentia1 equation and gives a sample paths. The ensemble of the paths reproduce the predictions given by ordinary quantum mechanics in an average. Each sample path has its own time dependent history, which enables us make a virtual quantum experiment. We formulate the tunneling time based on this approach and compare it with the Larmor time estimated from an experimental measurement of Larmor precession angles of tunneling neutrons.