Interference visibility as a witness of preparation contextuality via overlap inequalities
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arXiv
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| Format: | Preprint |
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2026
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| _version_ | 1866917498698334208 |
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| author | Siddiqui, Mohd Asad |
| author_facet | Siddiqui, Mohd Asad |
| contents | We show that standard multi-path interferometry, using only pairwise visibility measurements, provides an operational route to tests of preparation noncontextuality. Under ideal symmetric conditions, interference visibility directly encodes state overlaps, without requiring tomography or SWAP tests. For three paths, any jointly diagonalizable (coherence-free) description must satisfy $V_{12}^2+V_{23}^2-V_{13}^2\le 1$, where $V_{ij}$ are two-path visibilities. Pure qubit detector states violate this bound, achieving a maximal value of $5/4$. We generalize to arbitrary $n$-path interferometers and derive the tight qubit bound $S_n^{\max}=n\cos^2(π/2n)-1$ for all $n\ge3$, achieved by coplanar pure qubit states with uniform angular separation $π/n$. A robustness analysis yields explicit experimental thresholds. Under the operational equivalences used in overlap-based generalized noncontextuality frameworks, violations of these visibility inequalities also witness preparation contextuality. For $n$-cycle inequalities, only the pairwise visibilities appearing in the cycle need to be measured. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2605_14395 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Interference visibility as a witness of preparation contextuality via overlap inequalities Siddiqui, Mohd Asad Quantum Physics We show that standard multi-path interferometry, using only pairwise visibility measurements, provides an operational route to tests of preparation noncontextuality. Under ideal symmetric conditions, interference visibility directly encodes state overlaps, without requiring tomography or SWAP tests. For three paths, any jointly diagonalizable (coherence-free) description must satisfy $V_{12}^2+V_{23}^2-V_{13}^2\le 1$, where $V_{ij}$ are two-path visibilities. Pure qubit detector states violate this bound, achieving a maximal value of $5/4$. We generalize to arbitrary $n$-path interferometers and derive the tight qubit bound $S_n^{\max}=n\cos^2(π/2n)-1$ for all $n\ge3$, achieved by coplanar pure qubit states with uniform angular separation $π/n$. A robustness analysis yields explicit experimental thresholds. Under the operational equivalences used in overlap-based generalized noncontextuality frameworks, violations of these visibility inequalities also witness preparation contextuality. For $n$-cycle inequalities, only the pairwise visibilities appearing in the cycle need to be measured. |
| title | Interference visibility as a witness of preparation contextuality via overlap inequalities |
| topic | Quantum Physics |
| url | https://arxiv.org/abs/2605.14395 |