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31,745 results on '"Li, Xiang-An"'

1. PSF Calibration of DAMPE for gamma-ray Observations

Author

Duan, Kai-Kai, Shen, Zhao-Qiang, Xu, Zun-Lei, Jiang, Wei, and Li, Xiang

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - High Energy Astrophysical Phenomena
Abstract

The DArk Matter Particle Explorer (DAMPE) is dedicated to exploring critical scientific domains including the indirect detection of dark matter, cosmic ray physics, and gamma ray astronomy. This study introduces a novel method for calibrating the Point Spread Function (PSF) of DAMPE, specifically designed to enhance the accuracy of gamma-ray observations. By leveraging data from regions near pulsars and bright Active Galactic Nuclei (AGNs), we have refined the PSF calibration process, resulting in an improved angular resolution that closely matches our observational data. This advancement significantly boosts the precision of gamma-ray detection by DAMPE, thereby contributing to its mission objectives in dark matter detection and gamma ray astronomy., Comment: 7 pages, 12 figures and 1 table. Accepted for publication in Astroparticle Physics

Published
2024
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2. A toy model to explain the missing bounce windows in the kink-antikink collisions

Author

Long, Lingxiao, Li, Xiang, and Jiang, Yunguo

Subjects
High Energy Physics - Theory
Abstract

We propose a toy model to reproduce the fractal structure of kink and antikink collisions on one topological sector of $\phi^6$ theory. Using the toy model, we investigate the missing bounce windows observed in the fractal structure, and show that the coupling between two oscillation modes modulate the emergence of the missing bounce windows. By numerical calculation, we present that the two bounce resonance corresponds to the lower eigenfrequency of the toy model.

Published
2024
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4. Variational Quantum Imaginary Time Evolution for Matrix Product State Ansatz with Tests on Transcorrelated Hamiltonians

Author

Li, Hao-En, Li, Xiang, Huang, Jia-Cheng, Zhang, Guang-Ze, Shen, Zhu-Ping, Zhao, Chen, Li, Jun, and Hu, Han-Shi

Subjects
Quantum Physics, Physics - Chemical Physics
Abstract

The matrix product state (MPS) ansatz offers a promising approach for finding the ground state of molecular Hamiltonians and solving quantum chemistry problems. Building on this concept, the proposed technique of quantum circuit MPS (QCMPS) enables the simulation of chemical systems using a relatively small number of qubits. In this study, we enhance the optimization performance of the QCMPS ansatz by employing the variational quantum imaginary time evolution (VarQITE) approach. Guided by McLachlan's variational principle, the VarQITE method provides analytical metrics and gradients, resulting in improved convergence efficiency and robustness of the QCMPS. We validate these improvements numerically through simulations of $\rm H_2$, $\rm H_4$, and $\rm LiH$ molecules. Additionally, given that VarQITE is applicable to non-Hermitian Hamiltonians, we evaluate its effectiveness in preparing the ground state of transcorrelated (TC) Hamiltonians. This approach yields energy estimates comparable to the complete basis set (CBS) limit while using even fewer qubits. Specifically, we perform simulations of the beryllium atom and $\rm LiH$ molecule using only three qubits, maintaining high fidelity with the CBS ground state energy of these systems. This qubit reduction is achieved through the combined advantages of both the QCMPS ansatz and transcorrelation. Our findings demonstrate the potential practicality of this quantum chemistry algorithm on near-term quantum devices., Comment: 15 pages, 8 figures

Published
2024
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5. Simulation of DAMPE silicon microstrip detectors in the $\rm Allpix^{2}$ framework

Author

Cui, Yu-Xin, Li, Xiang, Wang, Shen, Yue, Chuan, Wan, Qiang, Lei, Shi-Jun, Yuan, Guan-Wen, Hu, Yi-Ming, Wei, Jia-Ju, and Guo, Jian-Hua

Subjects
Physics - Instrumentation and Detectors, High Energy Physics - Experiment
Abstract

Silicon strip detectors have been widely utilized in space experiments for gamma-ray and cosmic-ray detections thanks to their high spatial resolution and stable performance. For a silicon micro-strip detector, the Monte Carlo simulation is recognized as a practical and cost-effective approach to verify the detector performance. In this study, a technique for the simulation of the silicon micro-strip detector with the $\rm Allpix^{2}$ framework is developed. By incorporating the electric field into the particle transport simulation based on Geant4, this framework could precisely emulate the carrier drift in the silicon micro-strip detector. The simulation results are validated using the beam test data as well as the flight data of the DAMPE experiment, which suggests that the $\rm Allpix^{2}$ framework is a powerful tool to obtain the performance of the silicon micro-strip detector.

Published
2024
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46. Improved Optimization for the Neural-network Quantum States and Tests on the Chromium Dimer

Author

Li, Xiang, Huang, Jia-Cheng, Zhang, Guang-Ze, Li, Hao-En, Shen, Zhu-Ping, Zhao, Chen, Li, Jun, and Hu, Han-Shi

Subjects
Physics - Chemical Physics, Quantum Physics
Abstract

The advent of Neural-network Quantum States (NQS) has significantly advanced wave function ansatz research, sparking a resurgence in orbital space variational Monte Carlo (VMC) exploration. This work introduces three algorithmic enhancements to reduce computational demands of VMC optimization using NQS: an adaptive learning rate algorithm, constrained optimization, and block optimization. We evaluate the refined algorithm on complex multireference bond stretches of $\rm H_2O$ and $\rm N_2$ within the cc-pVDZ basis set and calculate the ground-state energy of the strongly correlated chromium dimer ($\rm Cr_2$) in the Ahlrichs SV basis set. Our results achieve superior accuracy compared to coupled cluster theory at a relatively modest CPU cost. This work demonstrates how to enhance optimization efficiency and robustness using these strategies, opening a new path to optimize large-scale Restricted Boltzmann Machine (RBM)-based NQS more effectively and marking a substantial advancement in NQS's practical quantum chemistry applications., Comment: 13 pages, 9 figures, and 2 tables

Published
2024
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