Single-acquisition tomography of photonic qubits with structured media

• URL: http://arxiv.org/abs/2607.03052v1
• Date: Fri, 03 Jul 2026 07:42:01 GMT
• Title: Single-acquisition tomography of photonic qubits with structured media
• Abstract summary: Quantum state tomography is an essential tool for characterizing quantum systems.<n>Here, we introduce a platform that performs informationally complete measurements of photonic polarization qubits within a single acquisition.<n>We experimentally demonstrate single-frame quantum state tomography of both single- and two-photon polarization states.
• Score: 0.39089069256361736
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: Quantum state tomography is an essential tool for characterizing quantum systems and underpins nearly every experimental realization of quantum technologies. Conventional tomography relies on performing a sequence of projective measurements on many identical copies of a quantum state, requiring the measurement apparatus to be reconfigured between successive acquisitions. As the Hilbert-space dimension increases, the number of required measurements grows rapidly; in practice, additional overcomplete measurements are often performed to improve robustness to experimental imperfections. Here, we introduce a tomography platform based on structured anisotropic media that performs informationally complete measurements of photonic polarization qubits within a single acquisition. The approach employs three liquid-crystal metasurfaces with spatially varying optic-axis orientations that transform the input polarization into a far-field distribution of discrete transverse-momentum modes. Each diffraction pattern uniquely determines the polarization state, enabling its reconstruction without sequential changes to the measurement apparatus. Unlike previous implementations, our scheme is intrinsically photon-number independent: the same optical device operates identically for arbitrary photon numbers, while the desired photon-number sector can be selected afterwards through post-selection of the corresponding $n$-fold coincidence events. We experimentally demonstrate single-frame quantum state tomography of both single- and two-photon polarization states, providing a simple and scalable route toward efficient quantum-state characterization.

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