JUSTC

2023-7 Contents

2023, 53(7): 1-2.

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2023-7 Abstract

2023, 53(7): 1-2.

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Abstract:

Temperature-robust diamond magnetometry based on the double-transition method

Caijin Xie, Yunbin Zhu, Yijin Xie, Tingwei Li, Wenzhe Zhang, Yifan Wang, Xing Rong

2023, 53(7): 0701. doi: 10.52396/JUSTC-2022-0150

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Abstract:
As a promising solid-state sensor at room temperature, diamond magnetometers based on nitrogen-vacancy (NV) centers have been developed tremendously in recent years. Many studies have demonstrated its potential for achieving high spatial resolution and sensitivity. However, the temperature dependence of the zero-field splitting D of NV centers poses an enormous challenge for the application of diamond magnetometry, since it is difficult to avoid temperature drift in most application scenarios. Here, we demonstrate a type of temperature-robust diamond magnetometry based on the double-transition method. By utilizing both transitions between $|m_{\rm{s}}=0\rangle$ and $|m_{\rm{s}}=\pm1\rangle$ sublevels with incomplete degeneracy of the $|m_{\rm{s}}=\pm1\rangle$states, the impacts of D variations induced by temperature drift can be counteracted. The drift of magnetic field measurement result has been reduced by approximately 7-fold. With further improvements, the temperature-robust diamond magnetometry has the potential to be applied in biomagnetism and space science research.

Electronic correlation effects on stabilizing a perfect Kagome lattice and ferromagnetic fluctuation in LaRu₃Si₂

Yilin Wang

2023, 53(7): 0702. doi: 10.52396/JUSTC-2022-0182

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Abstract:
A perfect Kagome lattice features flat bands that usually lead to strong electronic correlation effects, but how electronic correlation, in turn, stabilizes a perfect Kagome lattice has rarely been explored. Here, we study this effect in a superconducting ($T_{\rm{c}} \sim 7.8$ K) Kagome metal LaRu₃Si₂ with a distorted Kagome plane consisting of pure Ru ions, using density functional theory plus $ U $ and plus dynamical mean-field theory. We find that increasing electronic correlation can stabilize a perfect Kagome lattice and induce substantial ferromagnetic fluctuations in LaRu₃Si₂. By comparing the calculated magnetic susceptibilities to experimental data, LaRu₃Si₂ is found to be on the verge of becoming a perfect Kagome lattice. It thus shows moderate but non-negligible electronic correlations and ferromagnetic fluctuations, which are crucial to understand the experimentally observed non-Fermi-liquid behavior and the pretty high superconducting $T_{\rm{c}}$ of LaRu₃Si₂.

A coherent study of e⁺e⁻→ωπ⁰, ωπ⁺π⁻, and ωη

Yan Wu, Qinsong Zhou, Wenbiao Yan, Guangshun Huang

2023, 53(7): 0704. doi: 10.52396/JUSTC-2023-0086

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In this work, a combined analysis is performed on the processes of $e^+e^-\to\omega\pi^0\pi^0$, $e^+e^-\to\omega\pi^+\pi^-$, and $e^+e^-\to\omega\eta$ to study possible $\omega$ excited states at approximately 2.2 GeV. The resonance parameters are extracted by simultaneous fits of the Born cross section line shapes of these processes. In the fit with one resonance, the mass and width are fitted to be $(2207\pm14)$ MeV$/c^2$ and $(104\pm16)$ MeV, respectively. The result is consistent with previous measurements. In the fit with two resonances, the mass and width for the first resonance are fitted to be $(2160\pm36)$ MeV$/c^2$ (solution I), $(2154\pm12)$ MeV$/c^2$ (solution II) and $(141\pm74)$ MeV (solution I), $(152\pm77)$ MeV (solution II), respectively. The mass and width for the second resonance are fitted to be $(2298\pm19)$ MeV$/c^2$ (solution I), $(2309\pm6)$ MeV$/c^2$ (solution II) and $(106\pm77)$ MeV (solution I), $(99\pm23)$ MeV (solution II), respectively. The result is consistent with the theoretical prediction of $\omega(4S)$ and $\omega(3D)$. The intermediate subprocesses in $e^+e^-\to\omega\pi^+\pi^-$ are analyzed using the resonance parameters of the previous fits in this work. In the fit with one resonance, the fitting result of $\varGamma^{e^+e^-}_{{\rm{R}}}B_{{\rm{R}}}$ is partially consistent with the previous result. In the fit with two resonances, the fitting result of $\varGamma^{e^+e^-}_{{\rm{R}}}B_{{\rm{R}}}$ is of the same order of magnitude as the theoretical prediction. This work may provide useful information for studying the light flavor vector meson family.

Design of a fiber cavity ion trap for a high-efficiency and high-rate quantum network node

Xing-Yu Bao, Jin-Ming Cui, Ding Fang, Wei-Bin Chen, Jian Wang, Yun-Feng Huang, Chuan-Feng Li, Guang-Can Guo

2023, 53(7): 0705. doi: 10.52396/JUSTC-2023-0005

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The main purpose of this paper is to design a novel coupled system of an ion trap and a fiber cavity. This integrated solution is achieved by fabricating a fiber cavity with a metal mask on the side and end faces of the fiber. The fiber cavity with the metal mask can transmit light and electric charges, and the metal mask on the fiber end-face can shield electric charges on the dielectric high-reflection film. This system is designed to trap a single $ ^{138}\text{Ba}^{+} $ ion and realize coupling of the fiber cavity to the fluorescence at a 493 nm wavelength of $ ^{138}\text{Ba}^{+} $. To efficiently collect fluorescent photons, we perform a theoretical analysis of the overall system to achieve optimal coupling of each individual part. The cavity length is designed to be $ 250 $ μm, and the optimized coupling parameters are $(g,\kappa,\gamma)/2{\text{π}}=(55,\;105,\;20)$ MHz. We also improve the stability and reliability of the system by analyzing the vibration, performance of the ion trap, and thermal stability. The core of the system is composed of materials with similar thermal expansion coefficients to improve thermal stability. The system uses spring connections to isolate vibrations inside and outside the vacuum chamber. We theoretically solve the difficulties of manufacturing the coupled system and have completed the experimental verification of some key technologies. The whole system is expected to be extended into a complex quantum network system to realize quantum computation and communication.

The effect of receptor interaction on the bacterial chemotactic adaptation rate

Shujian Ren, Chi Zhang, Rongjing Zhang

2023, 53(7): 0703. doi: 10.52396/JUSTC-2023-0058

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Different receptors have evolved in organisms to sense different stimuli in their surroundings. The interaction among the receptors can significantly increase sensory sensitivity and adaptation precision. To study the influence of interaction among different types of chemoreceptors on the adaptation rate in the bacterial chemotaxis signaling network, we systematically compared the adaptation time between the wild-type strain expressing mixed types of receptors and the mutant strain expressing only Tar receptors (namely, the Tar-only strain) under stepwise addition of different concentrations of L-aspartate using FRET (Förster resonance energy transfer) and bead assays. We find that the wild type exhibits faster adaptation than the mutant under the same concentration of saturated stimulus. In contrast, the wild type exhibits slower adaptation than the mutant under unsaturated stimuli that induce the same magnitude of response, and this is independent of the level of receptor expression. The same result is obtained for the network relaxation time by monitoring the steady-state rotational signal of the flagellar motors. By simulating bacterial chemotaxis with different adaptation rates in a stable gradient of chemoattractants, we confirm that the interaction of different types of receptors can effectively promote chemotaxis of Escherichia coli under a stable spatial gradient of attractants while ensuring minimum noise in the cell position distribution.

The NuSTAR extragalactic surveys: Source catalogs from the Extended Chandra Deep Field-South and the Chandra Deep Field-North

Tianyi Zhang, Yongquan Xue

2023, 53(7): 0706. doi: 10.52396/JUSTC-2023-0032

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We present a routinized and reliable method to obtain source catalogs from the Nuclear Spectroscopic Telescope Array (NuSTAR) extragalactic surveys of the Extended Chandra Deep Field-South (E-CDF-S) and Chandra Deep Field-North (CDF-N). The NuSTAR E-CDF-S survey covers a sky area of $\sim30'\times30'$ to a maximum depth of $\sim230\;{\rm{ks}}$ corrected for vignetting in the 3–24 keV band, with a total of 58 sources detected in our E-CDF-S catalog; the NuSTAR CDF-N survey covers a sky area of $\sim7'\times10'$ to a maximum depth of $\sim440\;{\rm{ks}}$ corrected for vignetting in the 3–24 keV band, with a total of 42 sources detected in our CDF-N catalog that is produced for the first time. We verify the reliability of our two catalogs by crossmatching them with the relevant catalogs from the Chandra X-ray observatory and find that the fluxes of our NuSTAR sources are generally consistent with those of their Chandra counterparts. Our two catalogs are produced following the exact same method and made publicly available, thereby providing a uniform platform that facilitates further studies involving these two fields. Our source-detection method provides a systematic approach for source cataloging in other NuSTAR extragalactic surveys.

Optimal matching for heterogeneous treatment effect estimation

Yun Cai, Shuguang Zhang

2023, 53(7): 0707. doi: 10.52396/JUSTC-2023-0033

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In observational studies, identifying subgroups and exploring heterogeneity is of practical significance. However, causal inference at the individual level is a challenging problem due to the absence of counterfactual outcomes and the presence of selection bias. To address this issue, we propose a general framework called TRIMATCH for estimating heterogeneous treatment effects. First, we find the optimal matching by solving a minimum average cost flow optimization problem in a tripartite graph network structure. Second, with the pseudo individual treatment effects acquired from the previous step, we establish a nonparametric regression model to predict heterogeneous treatment effects for individuals with diverse characteristics. Our experiments demonstrate the effectiveness of the proposed matching method and the interpretability of the results.

2023 Vol. 53, No. 7

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