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Advanced Photon Counting Techniques

Simulating noise channels in anti-relaxation coated Cs vapor cells for polarization-qubit quantum memories

Jing Su, Changhoon Park, Olivia Cong, Y. Shi, Xiao Tang, Thomas Gerrits, Oliver Slattery, Lijun Ma

Published Jun 12, 2026• 0 citations

Abstract

We present a simulation-based quantum process tomography study of polarization-qubit storage in warm cesium vapor cells with different coatings. The model incorporates experimentally measured retrieval efficiency as a function of storage time and includes three noise mechanisms: signal-to-noise–induced depolarizing admixture, transverse coherence decay (T2) and longitudinal relaxation (T1). Simulated polarization-analyzer scans are used to reconstruct the affine Bloch map of the memory channel at each storage time. From the reconstructed process, we extract effective depolarization, dephasing, and amplitude-damping parameters and quantify their individual contributions to fidelity loss. The analysis reveals that dephasing dominates infidelity growth, while SNR-driven depolarization becomes increasingly relevant at low retrieval efficiency. Comparative results for uncoated, paraffin-coated, and alkene-coated cells demonstrate coatingdependent coherence preservation and provide a quantitative framework for separating incoherent noise mechanisms in warm-vapor quantum memories.

DOI: 10.1117/12.3091427

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Atomic vapor-cell quantum memories are key devices for quantum information science. Anti-relaxation coatings on the inner surface of the cell suppress ground-state dephasing caused by atom-wall collisions, thereby improving memory performance. Nevertheless, systematic performance comparisons of vapor-cell quantum memories with different anti-relaxation coatings under identical conditions remain limited. Here, we experimentally compare quantum-memory performance in cesium vapor cells with and without anti-relaxation coatings-uncoated, paraffin-coated, and alkene-coated-under otherwise identical conditions to assess coating-dependent effects. Using electromagnetically induced transparency (EIT) as the light storage protocol, we characterize transmission, memory efficiency, and storage lifetime. The alkene-coated cell yields the largest enhancement in retrieval efficiency-more than fourfold relative to the uncoated cell and more than twofold relative to the paraffin-coated cell-while exhibiting a modest (approximately 16%) increase in storage lifetime. These results provide a systematic benchmark for evaluating anti-relaxation coatings and for this instance, identify alkene coatings as an effective choice for improving retrieval efficiency in warm-vapor-cell memories.

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