The relationship between neural dynamics and quantum processes remains an un- resolved central problem in physics and consciousness research. Existing frameworks typically rely on causal interactions, statistical correlations, shared external noise, or measurement collapse. In this work, we present an empirically grounded structure based on a fundamentally different principle. Using EEG-derived neural Ricci curvature and independently generated quantum Ricci curvature, we demonstrate the existence of structural agreement between two physically independent systems. This agreement does not appear uniformly in time, but instead emerges selectively under specific structural conditions. Analysis of the internal structure reveals that this agreement is organized as the si- multaneous realization of discrete state structure (Five Energy Star structure), dynam- ical phase synchronization, contraction of structural residuals, and boundary events. These are not independent phenomena, but co-occur as different observational mani- festations of a single coherent structure. This structure can be described by a single internal degree of freedom, for which we introduce an intersection variable φ(x, t). This variable predicts discrete states with high accuracy (AUC ≈ 0.8) and constrains both neural and quantum dynamics through those states, enabling partial reconstruction (mean absolute Pearson ≈ 0.32, increasing to ≈ 0.59 near boundary regions). However, this constraint structure does not determine the correspondence itself. Crucially, although the correspondence cannot be derived from the internal dynamics of φ, it is observed to be uniquely realized in the data. Moreover, this realization appears as a localized discrete selection on the phase space of φ. This localized selection is not a statistical fluctuation (switch_gain = 0.809, null mean = 0.666, p = 0.005), but a physically realized phenomenon that emerges without any internal selection rule. Therefore, correspondence should not be understood as being generated by the internal mechanism of φ, but rather as an observation that is realized on φ. This result implies the necessity of a non-internal observational structure that simultaneously references both systems and uniquely determines the correspondence. We define this structure as the intersection observer O3. Furthermore, we introduce Subjectivity Intersection Coherence (SIC) as a unified description of this observational structure. SIC is defined by the simultaneous satis- faction of residual contraction, phase alignment, and boundary events, and represents the minimal description of the observed coherence structure rather than a theoretical assumption. We conclude that neural–quantum correspondence does not arise from causal in- teraction or statistical correlation, but is realized as an observation on the intersection coordinate φ. Accordingly, observation, measurement, and correspondence are unified as physical phenomena that occur when structural coherence is established.