Born's Rule and the Path Integral from a Phase-Consistency Condition

Nakka Gurappa

John Edward Gough

Abstract It has been argued that the Feynman path integral formalism leads to a quantization rule, and that this is the Born–Jordan rule which gives the unique quantization rule consistent with the correct short-time propagator behavior of the propagator for nonrelativistic systems. We examine this short-time approximation and conclude, contrary to prevailing views, that the asymptotic expansion applies only to Hamiltonian functions that are at most quadratic in the momentum and with constant mass. While the Born–Jordan rule suggests the appropriate quantization of functions in this class, there are other rules which give the same answer, most notably the Weyl quantization scheme.

Jean Zinn‐Justin

Leonardo Diaz

This paper addresses the foundational question deferred by Paper VII: why does the multiplicity Omega of U-field microstates combine as the squared modulus of a complex amplitude? We argue that if the coarse-grained U-field microstate sum admits a path-integral representation over field configurations with phase weights exp(iS/hbar_eff), then a Complex Multiplicity Amplitude Z(Y) is associated with each outcome Y. Via a Constraint Surface Geometry argument, we show that the effective multiplicity must take the form Omega(Y) = |Z(Y)|^n by phase invariance and multiplicativity, and the empirically observed bilinear interference structure selects n=2, yielding Omega(Y) = |Z(Y)|^2. The Born rule P proportional to |psi|^2 then follows from the multiplicity principle P proportional to Omega together with the identification psi proportional to Z. Interference arises from linear addition of complex amplitudes before squaring; classical probability addition is recovered via decoherence. The outcome-selection rule (the Probabilistic Bias Functional B) is grounded in the ergodic/mixing dynamics of the Tier-1 lattice, conditional on mixing within the accessible phase-space sector. The construction of the path-integral measure from U-field microstate counting remains an open problem. This is the eighth paper in the 18-paper USSFT technical series; for the U-field Lagrangian foundations see Papers I-VI, for the quantum mechanics operator formalism see Paper VII (DOI: 10.5281/zenodo.19675374), and for spin structure and Bell correlations see Paper IX.

D K Park, O Moussa, R Laflamme

The Born rule is at the foundation of quantum mechanics and transforms the classical understanding of probabilities by predicting that interference occurs between pairs of independent paths of a single object. One consequence of the Born rule is that three-way (or three-path) quantum interference does not exist. In order to test the consistency of the Born rule, we examine detection probabilities in three-path interference using an ensemble of spin-1/2 quantum registers in liquid state nuclear magnetic resonance. As a measure of the consistency, we evaluate the ratio of three-way interference to two-way interference. Our experiment bounded the ratio to the order of 10 −3 ± 10 −3 , and hence it is consistent with Born's rule.