Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

The Schrödinger Equation as a Transfer Operator on an Action Graph: Discrete Propagator, Rational Unitary Realization, and Continuous Limit

Jonatan P. camargo

Published Apr 3, 2026• 0 citations
Publisher

Abstract

We present a structural derivation of Schrödinger dynamics from a discrete ontology in which physical space is described by an action graph \(G=(V,E)\), rather than a primary continuum. The starting point is not an \emph{a posteriori} numerical discretization of an already assumed continuous differential equation, but the direct definition of a local Hamiltonian on the fundamental network. It is first shown that the exact one-step time evolution is given by a discrete unitary propagator \[ U(\Delta t)=\exp\!\left(-\frac{i\Delta t}{\hbar}\hat H\right). \] In the one-dimensional homogeneous case with nearest-neighbor coupling and constant potential, the exact spatial symbol of this propagator is obtained. Next, we demonstrate that its first-order minimal local expansion produces a three-coefficient bilateral spatial realization, i.e., a minimal FIR. However, it is also proven that this truncated realization is not unitary when iterated, so it cannot represent the exact fundamental dynamics. The structural correction of the problem naturally leads to the Cayley rational unitary realization, \[ U_{\mathrm C}(\Delta t) = \left(I-\frac{i\Delta t}{2\hbar}\hat H\right) \left(I+\frac{i\Delta t}{2\hbar}\hat H\right)^{-1}, \] which preserves the norm exactly at the discrete level and reveals that fundamental quantum evolution cannot be reduced to a strictly local FIR law of finite support. Thus, the rigorous result of this work is twofold: the FIR form appears as a first-order minimal local realization, while unitarity requires an exact operator or a rational unitary one whose realization is no longer of finite spatial support. Finally, we show that the \(\Delta x,\Delta t\to 0\) limit recovers the continuous Schrödinger equation. The central conclusion is that continuous quantum dynamics must be understood as the macroscopic shadow of a discrete unitary propagator on an action graph, and not as an ontologically primary law.

DOI
10.5281/zenodo.19394859

Related papers

Structural Operators as Unitary Filters: Phase, Propagation, and Effective Geometry in the Action--Phase Program

Jonatan P. camargo

In this work, we propose a structural reformulation of the Action--Phase program based on the interpretation of operators as unitary linear filters acting on the physical phase \(\phi = S/\hbar\). The central thesis is that the various effective sectors of physics can be reinterpreted as regimes of operator action on the phase and its gradient, rather than independent collections of final equations. We start from the chain already established in previous works --- action \(\to\) phase \(\to\) episodic compatibility \(\to\) event network \(\to\) structural operator --- and show that the emergent local linear dynamics admits a natural reading in terms of filter theory. In particular, the effective network operator can be seen as a transfer function, whose Cayley realization defines a local unitary all-pass filter of strictly unitary modulus. This structure provides a direct interpretation of unitarity as information conservation. We also show that the spatial variation of the local coefficients of the operator induces modulation of the phase response, leading to the definition of a local quasi-energy \(\Omega(x,k)\). In the slowly varying regime, this structure reproduces an effective dynamics governed by Hamilton--Jacobi-type equations, recovering trajectories previously obtained via the eikonal approach. In this framework, gravity can be reinterpreted as the geometric optics of phase propagation in a structurally inhomogeneous network. As an operational illustration, we present a comparative numerical experiment between discrete unitary evolution (Cayley realization) and explicit integration schemes of the semidiscrete Schrödinger equation. The results show that the unitary formulation preserves the norm at machine-level precision and remains stable in intense potential regimes, while explicit schemes exhibit accumulated drift and more severe time-step restrictions. This evidences that dynamics can be implemented as the iterative application of local unitary operators. The results do not constitute a complete gravitational theory nor do they replace established continuous formulations, but they identify a unifying mathematical structure that organizes the propagation, modulation, and refraction of the phase in a non-ad hoc manner and without circular reasoning. This structure suggests an extension program based on derivations and direct numerical tests, aimed at the explicit recovery of known gravitational results from phase dynamics.

•Apr 3, 2026•0 citations

Part 7_The Structural Origin of Schrödinger-Type Dynamics from JS–SH Discrete Geometry

Seung Woo Hong

This work derives a Schrödinger-type evolution equation from first principles, starting exclusively from a discrete structural framework composed of JS-cells and SH-hub couplings.No quantum-mechanical postulates, complex wavefunctions, canonical quantization rules, or predefined physical constants are assumed at any stage. Each JS-cell carries a minimal two-channel real internal state, and neighboring cells interact locally through SH-hubs.Imposing a single universal requirement — strict conservation of a global quadratic structural norm — uniquely constrains the admissible dynamics. We show that: Norm preservation enforces an internal SO(2) symmetry, The unique generator of this symmetry is a real antisymmetric matrix J, Complex numbers and phase emerge only as a notation, not as assumptions, Local SH-hub connectivity forces a discrete Laplacian structure, The ordered continuum limit uniquely selects a first-order conservative time evolution. Only at the final stage is the resulting continuum equation identified as belonging to the Schrödinger universality class.Planck’s constant, mass, and potential appear as emergent structural parameters, fixed by discrete spatial and temporal scales. The derivation is non-circular, fully constructive, and independent of standard quantum axioms.An optional numerical sanity check confirms exact norm preservation and Schrödinger-class dispersion from the discrete update rule. This work provides a structural explanation for why Schrödinger dynamics exists, rather than assuming it.

•Jan 20, 2026•1 citation

From Nearest-Neighbor Propagation to the Schrödinger Equation: A Rigorous Derivation Based on Step Counting and Fluctuation Corrections

YanZhuang

Abstract Since its introduction in 1926, the Schr¨odinger equation has been regarded as a fundamental postulate of quantum mechanics, with its physical origin—especially the appearance of the imaginary unit i—remaining unexplained. In this paper, within the framework of Marker Ontology and starting from the nearest-neighbor propagation mechanism of spatial primitives, we rigorously prove that the contin uum limit of nearest-neighbor propagation naturally converges to the Schr¨odinger equation. The imaginary unit i is not an introduced mathematical assumption, but rather an imaginary component that emerges naturally from the expansion of the complex representation eiϕ of step counting in the continuum limit. This imaginary component couples with the spatial diffusion term, endowing the effective diffusion coefficient with an intrinsic imaginary part. The non-vanishing of the fluctuation cross-term is numerically verified through Monte Carlo simulation, confirming that the magnitude of the second-order fluctuation term is sufficient to affect the real part of the effective diffusion coefficient, thereby providing numerical support for the cancellation of the real diffusion term and the transition to purely unitary evo lution. We further provide an order-of-magnitude estimate of the characteristic step number N0 (N0 = λ/ℓ0 ∼ 1028) from the properties of the primitive network, and demonstrate the self-consistency relation between N0 and the quantum of action ℏ. This paper provides the Schr¨odinger equation with a physical foundation that has been absent since its inception

•Jun 30, 2026•0 citations

Physical Propagation as Spectral Dynamics of Unitary Operators: Bilocal Structure, Homogeneity, and Spectral Diagonalization

Jonatan P. camargo

We present a structural formulation of physical dynamics in which time evolution is directly described by a unitary propagation operator, rather than being primarily introduced by continuous differential equations. Starting from the relationship between action and phase, $\phi=S/\hbar$, and the variational construction of self-adjoint structural operators, it is shown that propagation can be exactly expressed through a bilocal kernel $W(x,y)$ associated with an operator $\hat W=f(\hat H)$, with $\hat H=\hat H^\dagger$. We demonstrate that the structural homogeneity of the kernel, characterized by the condition $W(x,y)=W(x-y)$, implies the spectral diagonalization of the propagation operator. In this regime, the evolution becomes decoupled between modes, and the absence of spectral mixing provides a minimal structural expression of conservation. It is further shown that the off-diagonal structure of the bilocal kernel completely determines the connectivity of propagation between states, allowing the effective locality of the dynamics to be characterized in terms of the support of $W(x,y)$. The analysis establishes, in a controlled manner, the relationship between the bilocal description and the Lagrangian formulation, indicating that the operatorial structure replaces, at the considered level, the need for a continuous sum over trajectories, without excluding its recovery as an effective limit in appropriate regimes. The obtained results show that dynamics can be entirely organized in terms of the propagation operator and its spectral decomposition, in which the nodal representation and the spectral representation emerge as complementary descriptions of the same structure. The scope of this work is strictly structural: it does not propose a complete reconstruction of quantum mechanics, nor a general gravitational theory, nor a formulation for multiparticle systems or measurement processes. The objective is to establish a minimal layer in which physical propagation is encoded by the unitary operator and its spectral structure.

•Apr 12, 2026•0 citations

Position--Momentum Duality as Spectral Diagonalization of Bilocal Propagation A Continuation of the Action--Phase Program

Jonatan P. camargo

The objective of this work is to investigate whether the position--momentum duality can be reformulated, without ad hoc hypotheses and without circular reasoning, as a direct consequence of the spectral structure of bilocal unitary propagation. We start from the architecture already established in the Action--Phase program: the physical phase is given by \(\phi=S/\hbar\); self-adjoint structural operators organize the dynamics on a discrete lattice; such operators admit interpretation as unitary filters via Cayley realization; and the discrete unitary evolution can be written exactly as propagation by a bilocal kernel \(W(x,y)\). The central question is to determine under what hypotheses this bilocal kernel can be represented as a function of a self-adjoint structural operator, \[ \hat W=f(\hat H), \qquad \hat H=\hat H^\dagger, \] and how this structure implies the existence of an intrinsic spectral basis in which the propagation becomes diagonal. It is shown, step by step, that the spectral decomposition of \(\hat H\) induces a corresponding decomposition of the kernel, \[ W(x,y)=\sum_n f(\lambda_n)\,\phi_n(x)\phi_n^*(y), \] so that the unitary evolution begins to act multiplicatively on the spectral modes, \[ \widetilde\Psi_n(t+\Delta t)=f(\lambda_n)\widetilde\Psi_n(t), \] without the introduction of additional structures. In the homogeneous case, it is demonstrated that the eigenfunctions of the structural operator are discrete Fourier modes and that the continuous spectral parameter coincides with the usual wavenumber. In this regime, the spectral representation exactly reproduces the momentum sector of standard quantum mechanics. Outside this case, ``momentum'' is reinterpreted more generally as the spectral coordinate of the operator generating the propagation. The result of this stage is, therefore, conceptually precise: the position--momentum duality does not need to be postulated as an ontological duplication, but emerges as a duality between the nodal basis and the spectral basis of the same structural operator that governs the unitary propagation. The work does not intend, at this stage, to completely reconstruct the theory of canonical observables, nor to definitively resolve multiparticle systems or formulate a general covariant theory. Its role is to establish the minimum layer in which the spectral structure of propagation provides the mathematical origin of position--momentum duality, opening a controlled continuation program for these problems.

•Apr 6, 2026•0 citations

The Vacuum as a Unitary Adaptive Convolution Operator: A Variational Extension of the Action--Phase Program Beyond the Local Formulation

Jonatan P. camargo

This work develops the direct continuation of the Action--Phase program following the reinterpretation of structural operators as unitary filters and the derivation of the scalar delay equation. The objective is to establish, without ad hoc introductions, circular reasoning, or undue duplication of degrees of freedom, the minimal bilocal formulation in which discrete unitary propagation is treated as the action of a spatial convolution kernel. Starting from the chain \[ \text{action} \;\Longrightarrow\; \text{phase} \;\Longrightarrow\; \text{structural operator} \;\Longrightarrow\; \text{unitary filter}, \] it is initially shown that the Cayley realization of a self-adjoint structural operator admits an exact rewriting as propagation by a strictly unitary bilocal kernel \(W(x,y)\) on a discrete spatial basis. Next, this kernel is identified as the minimal structural variable of the new formulation, strictly distinguishing it from the propagated state \(\Psi\), the local scalar field \(\Theta(x)\), and the quasi-energy \(\Omega(x,k)\), which are now understood at different levels of the theory's physical hierarchy. Under hypotheses of minimal bilocal locality, structural hermiticity, coercivity, minimal differential order, and minimal coupling to the phase state, the variational functional of the kernel is constructed and the corresponding Euler--Lagrange equation is derived. Finally, it is shown that the previous scalar delay theory does not constitute an independent construction but arises as the local/diagonal sector of the bilocal structure obtained here. The result of this stage is, therefore, precise and limited: to establish the minimal bilocal layer of adaptive unitary propagation over a structural network. The work does not intend, at this stage, to provide a complete theory of multipartite entanglement, turbulence, strong gravitational regimes, or covariant extensions. Its role is more fundamental: to provide the explicit variational basis from which such problems can be reformulated and investigated within a unified framework of discrete unitary propagation.

•Apr 6, 2026•0 citations
We present a structural derivation of Schrödinger dynamics from a discrete ontology in which physical space is described by an action graph (G=(V,E)), rather than a primary continuum. The starting point is not an \emph{a posteriori} numerical discretization of an already assumed continuous differential equation, but the direct definition of a local Hamiltonian on the fundamental network. It is first shown that the exact one-step time evolution is given by a discrete unitary propagator [ U(\Delta t)=\exp!\left(-\frac{i\Delta t}{\hbar}\hat H\right). ] In the one-dimensional homogeneous case with nearest-neighbor coupling and constant potential, the exact spatial symbol of this propagator is obtained. Next, we demonstrate that its first-order minimal local expansion produces a three-coefficient bilateral spatial realization, i.e., a minimal FIR. However, it is also proven that this truncated realization is not unitary when iterated, so it cannot represent the exact fundamental dynamics. The structural correction of the problem naturally leads to the Cayley rational unitary realization, [ U_{\mathrm C}(\Delta t) = \left(I-\frac{i\Delta t}{2\hbar}\hat H\right) \left(I+\frac{i\Delta t}{2\hbar}\hat H\right)^{-1}, ] which preserves the norm exactly at the discrete level and reveals that fundamental quantum evolution cannot be reduced to a strictly local FIR law of finite support. Thus, the rigorous result of this work is twofold: the FIR form appears as a first-order minimal local realization, while unitarity requires an exact operator or a rational unitary one whose realization is no longer of finite spatial support. Finally, we show that the (\Delta x,\Delta t\to 0) limit recovers the continuous Schrödinger equation. The central conclusion is that continuous quantum dynamics must be understood as the macroscopic shadow of a discrete unitary propagator on an action graph, and not as an ontologically primary law.
In this work, we propose a structural reformulation of the Action--Phase program based on the interpretation of operators as unitary linear filters acting on the physical phase ϕ=S/ℏ\phi = S/\hbarϕ=S/ℏ. The central thesis is that the various effective sectors of physics can be reinterpreted as regimes of operator action on the phase and its gradient, rather than independent collections of final equations. We start from the chain already established in previous works --- action →\to→ phase →\to→ episodic compatibility →\to→ event network →\to→ structural operator --- and show that the emergent local linear dynamics admits a natural reading in terms of filter theory. In particular, the effective network operator can be seen as a transfer function, whose Cayley realization defines a local unitary all-pass filter of strictly unitary modulus. This structure provides a direct interpretation of unitarity as information conservation. We also show that the spatial variation of the local coefficients of the operator induces modulation of the phase response, leading to the definition of a local quasi-energy Ω(x,k)\Omega(x,k)Ω(x,k). In the slowly varying regime, this structure reproduces an effective dynamics governed by Hamilton--Jacobi-type equations, recovering trajectories previously obtained via the eikonal approach. In this framework, gravity can be reinterpreted as the geometric optics of phase propagation in a structurally inhomogeneous network. As an operational illustration, we present a comparative numerical experiment between discrete unitary evolution (Cayley realization) and explicit integration schemes of the semidiscrete Schrödinger equation. The results show that the unitary formulation preserves the norm at machine-level precision and remains stable in intense potential regimes, while explicit schemes exhibit accumulated drift and more severe time-step restrictions. This evidences that dynamics can be implemented as the iterative application of local unitary operators. The results do not constitute a complete gravitational theory nor do they replace established continuous formulations, but they identify a unifying mathematical structure that organizes the propagation, modulation, and refraction of the phase in a non-ad hoc manner and without circular reasoning. This structure suggests an extension program based on derivations and direct numerical tests, aimed at the explicit recovery of known gravitational results from phase dynamics.
This work derives a Schrödinger-type evolution equation from first principles, starting exclusively from a discrete structural framework composed of JS-cells and SH-hub couplings.No quantum-mechanical postulates, complex wavefunctions, canonical quantization rules, or predefined physical constants are assumed at any stage. Each JS-cell carries a minimal two-channel real internal state, and neighboring cells interact locally through SH-hubs.Imposing a single universal requirement — strict conservation of a global quadratic structural norm — uniquely constrains the admissible dynamics. We show that: Norm preservation enforces an internal SO(2) symmetry, The unique generator of this symmetry is a real antisymmetric matrix J, Complex numbers and phase emerge only as a notation, not as assumptions, Local SH-hub connectivity forces a discrete Laplacian structure, The ordered continuum limit uniquely selects a first-order conservative time evolution. Only at the final stage is the resulting continuum equation identified as belonging to the Schrödinger universality class.Planck’s constant, mass, and potential appear as emergent structural parameters, fixed by discrete spatial and temporal scales. The derivation is non-circular, fully constructive, and independent of standard quantum axioms.An optional numerical sanity check confirms exact norm preservation and Schrödinger-class dispersion from the discrete update rule. This work provides a structural explanation for why Schrödinger dynamics exists, rather than assuming it.
Abstract Since its introduction in 1926, the Schr¨odinger equation has been regarded as a fundamental postulate of quantum mechanics, with its physical origin—especially the appearance of the imaginary unit i—remaining unexplained. In this paper, within the framework of Marker Ontology and starting from the nearest-neighbor propagation mechanism of spatial primitives, we rigorously prove that the contin uum limit of nearest-neighbor propagation naturally converges to the Schr¨odinger equation. The imaginary unit i is not an introduced mathematical assumption, but rather an imaginary component that emerges naturally from the expansion of the complex representation eiϕ of step counting in the continuum limit. This imaginary component couples with the spatial diffusion term, endowing the effective diffusion coefficient with an intrinsic imaginary part. The non-vanishing of the fluctuation cross-term is numerically verified through Monte Carlo simulation, confirming that the magnitude of the second-order fluctuation term is sufficient to affect the real part of the effective diffusion coefficient, thereby providing numerical support for the cancellation of the real diffusion term and the transition to purely unitary evo lution. We further provide an order-of-magnitude estimate of the characteristic step number N0 (N0 = λ/ℓ0 ∼ 1028) from the properties of the primitive network, and demonstrate the self-consistency relation between N0 and the quantum of action ℏ. This paper provides the Schr¨odinger equation with a physical foundation that has been absent since its inception
We present a structural formulation of physical dynamics in which time evolution is directly described by a unitary propagation operator, rather than being primarily introduced by continuous differential equations. Starting from the relationship between action and phase, ϕ=S/ℏ\phi=S/\hbarϕ=S/ℏ, and the variational construction of self-adjoint structural operators, it is shown that propagation can be exactly expressed through a bilocal kernel W(x,y)W(x,y)W(x,y) associated with an operator W^=f(H^)\hat W=f(\hat H)W^=f(H^), with H^=H^†\hat H=\hat H^\daggerH^=H^†. We demonstrate that the structural homogeneity of the kernel, characterized by the condition W(x,y)=W(x−y)W(x,y)=W(x-y)W(x,y)=W(x−y), implies the spectral diagonalization of the propagation operator. In this regime, the evolution becomes decoupled between modes, and the absence of spectral mixing provides a minimal structural expression of conservation. It is further shown that the off-diagonal structure of the bilocal kernel completely determines the connectivity of propagation between states, allowing the effective locality of the dynamics to be characterized in terms of the support of W(x,y)W(x,y)W(x,y). The analysis establishes, in a controlled manner, the relationship between the bilocal description and the Lagrangian formulation, indicating that the operatorial structure replaces, at the considered level, the need for a continuous sum over trajectories, without excluding its recovery as an effective limit in appropriate regimes. The obtained results show that dynamics can be entirely organized in terms of the propagation operator and its spectral decomposition, in which the nodal representation and the spectral representation emerge as complementary descriptions of the same structure. The scope of this work is strictly structural: it does not propose a complete reconstruction of quantum mechanics, nor a general gravitational theory, nor a formulation for multiparticle systems or measurement processes. The objective is to establish a minimal layer in which physical propagation is encoded by the unitary operator and its spectral structure.
The objective of this work is to investigate whether the position--momentum duality can be reformulated, without ad hoc hypotheses and without circular reasoning, as a direct consequence of the spectral structure of bilocal unitary propagation. We start from the architecture already established in the Action--Phase program: the physical phase is given by ϕ=S/ℏ\phi=S/\hbarϕ=S/ℏ; self-adjoint structural operators organize the dynamics on a discrete lattice; such operators admit interpretation as unitary filters via Cayley realization; and the discrete unitary evolution can be written exactly as propagation by a bilocal kernel W(x,y)W(x,y)W(x,y). The central question is to determine under what hypotheses this bilocal kernel can be represented as a function of a self-adjoint structural operator, W^=f(H^),H^=H^†, \hat W=f(\hat H), \qquad \hat H=\hat H^\dagger, W^=f(H^),H^=H^†, and how this structure implies the existence of an intrinsic spectral basis in which the propagation becomes diagonal. It is shown, step by step, that the spectral decomposition of H^\hat HH^ induces a corresponding decomposition of the kernel, W(x,y)=∑nf(λn) ϕn(x)ϕn∗(y), W(x,y)=\sum_n f(\lambda_n)\,\phi_n(x)\phi_n^*(y), W(x,y)=∑n​f(λn​)ϕn​(x)ϕn∗​(y), so that the unitary evolution begins to act multiplicatively on the spectral modes, Ψ~n(t+Δt)=f(λn)Ψ~n(t), \widetilde\Psi_n(t+\Delta t)=f(\lambda_n)\widetilde\Psi_n(t), Ψn​(t+Δt)=f(λn​)Ψn​(t), without the introduction of additional structures. In the homogeneous case, it is demonstrated that the eigenfunctions of the structural operator are discrete Fourier modes and that the continuous spectral parameter coincides with the usual wavenumber. In this regime, the spectral representation exactly reproduces the momentum sector of standard quantum mechanics. Outside this case, ``momentum'' is reinterpreted more generally as the spectral coordinate of the operator generating the propagation. The result of this stage is, therefore, conceptually precise: the position--momentum duality does not need to be postulated as an ontological duplication, but emerges as a duality between the nodal basis and the spectral basis of the same structural operator that governs the unitary propagation. The work does not intend, at this stage, to completely reconstruct the theory of canonical observables, nor to definitively resolve multiparticle systems or formulate a general covariant theory. Its role is to establish the minimum layer in which the spectral structure of propagation provides the mathematical origin of position--momentum duality, opening a controlled continuation program for these problems.
This work develops the direct continuation of the Action--Phase program following the reinterpretation of structural operators as unitary filters and the derivation of the scalar delay equation. The objective is to establish, without ad hoc introductions, circular reasoning, or undue duplication of degrees of freedom, the minimal bilocal formulation in which discrete unitary propagation is treated as the action of a spatial convolution kernel. Starting from the chain action  ⟹  phase  ⟹  structural operator  ⟹  unitary filter, \text{action} \;\Longrightarrow\; \text{phase} \;\Longrightarrow\; \text{structural operator} \;\Longrightarrow\; \text{unitary filter}, action⟹phase⟹structural operator⟹unitary filter, it is initially shown that the Cayley realization of a self-adjoint structural operator admits an exact rewriting as propagation by a strictly unitary bilocal kernel W(x,y)W(x,y)W(x,y) on a discrete spatial basis. Next, this kernel is identified as the minimal structural variable of the new formulation, strictly distinguishing it from the propagated state Ψ\PsiΨ, the local scalar field Θ(x)\Theta(x)Θ(x), and the quasi-energy Ω(x,k)\Omega(x,k)Ω(x,k), which are now understood at different levels of the theory's physical hierarchy. Under hypotheses of minimal bilocal locality, structural hermiticity, coercivity, minimal differential order, and minimal coupling to the phase state, the variational functional of the kernel is constructed and the corresponding Euler--Lagrange equation is derived. Finally, it is shown that the previous scalar delay theory does not constitute an independent construction but arises as the local/diagonal sector of the bilocal structure obtained here. The result of this stage is, therefore, precise and limited: to establish the minimal bilocal layer of adaptive unitary propagation over a structural network. The work does not intend, at this stage, to provide a complete theory of multipartite entanglement, turbulence, strong gravitational regimes, or covariant extensions. Its role is more fundamental: to provide the explicit variational basis from which such problems can be reformulated and investigated within a unified framework of discrete unitary propagation.