arXiv subjects

Yanli Shi

Publications and source records attributed to Yanli Shi.

3 recordsLinked to original sources

arXiv2026

On Demand magnetic-Doppler nuclear frequency comb memory for hard X-ray photons

Nuclear quantum memories in the hard X-ray regime offer some key advantages over their optical counterparts, such as broader bandwidth and lower background noise. A Doppler frequency comb protocol has been theoretically proposed [X. Zhang \textit{et al.}, Phys. Rev. Lett. \textbf{123}, 250504 (2019)] and recently demonstrated experimentally [S. Velten \textit{et al.}, Sci. Adv. \textbf{10}, eadn9825 (2024)] for the storage and retrieval of X-ray photons. However, achieving on-demand retrieval remains challenging because of the requirement for precise and synchronous mechanical motion of multiple absorbers. We propose a hybrid, magnetic-Doppler nuclear frequency comb composed of Doppler-shifted resonant absorbers with lifted nuclear spin degeneracy, which expands the Doppler comb structure. By synchronously reversing the directions of both the magnetic fields and absorber velocities, the system achieves time-reversed phase evolution dynamics that allows for efficient on-demand photon retrieval with significantly reduced mechanical complexity.

quant-ph↗

arXiv2026

Quantum Imaging via Kurtosis-Difference Weighted Covariance on 2D Camera

Camera-based quantum imaging detects spatially correlated photon pairs from spontaneous parametric down-conversion (SPDC). Conventional covariance methods typically require tens of thousands of frames to extract weak correlations from noise. While thick crystals can increase photon flux, they generate photon pairs from multiple emission positions within the crystal, producing multiple correlation centers with complex pairing geometries. In addition, conventional covariance methods assume a single pre-selected correlation center and cannot fully exploit these distributed correlations. We demonstrate that kurtosis difference, a fourth-order statistic measuring tail similarity, effectively discriminates correlated pixel pairs even when correlation coefficients remain low. Weighting covariance by an exponential function of absolute kurtosis difference can select symmetric pixels while preserving true coincidences. This kurtosis weighting automatically identifies correlated pairs within a broad search region and accommodates multiple pairing geometries without requiring precise correlation center calibration. At 5000 frames, our method yields a contrast-to-noise ratio (CNR) exceeding 7, whereas standard covariance remains below 2. Compared with standard covariance, the method reduces the acquisition time by 40-fold and could enable practical quantum imaging in sparse correlated-photon regimes.

quant-ph↗

arXiv2025

On-Demand Zeeman Nuclear Frequency Comb Quantum Memory

The emerging hard X-ray - nuclear interfaces offer unique potential advantages over traditional optical-atomic interfaces for room-temperature, solid-state quantum information processing, including lower background noise, tighter focusing, and exceptionally high resonance quality. Leveraging such interfaces, a major milestone was recently achieved with the first implementation of nuclear quantum memory in the hard X-ray range [S. Velten et al., Nuclear quantum memory for hard X-ray photon wave packets, Sci. Adv. 10, eadn9825 (2024)] using the Doppler frequency comb protocol. However, this approach relies on the synchronous mechanical motion of multiple nuclear absorbers, posing experimental challenges for on-demand photon retrieval. We propose an on-demand hard X-ray quantum memory based on reversing the direction of an external magnetic field in a single stationary solid-state nuclear absorber with sets of Zeeman sublevels. This scheme is exemplified by the quantum storage of an 1.41-$\mu$s single photon wave packet at 6.2 keV for over 10 $\mu$s in a $^{181}$Ta metallic foil, providing a feasible pathway for the first experimental demonstration of on-demand hard X-ray photon storage.

quant-ph↗