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121 results on '"Yang Qi"'

16. Dissipative preparation of qutrit entanglement via periodically modulated Rydberg double antiblockade

Author

Ai-Dong Zhu, Zhao Jin, Shou Zhang, Wei-Jiang Gong, Shi-Lei Su, and Yang Qi

Subjects
Physics, Quantum network, business.industry, Quantum Physics, 02 engineering and technology, Quantum entanglement, 021001 nanoscience & nanotechnology, 01 natural sciences, Atomic and Molecular Physics, and Optics, 010309 optics, symbols.namesake, Optics, Quantum mechanics, 0103 physical sciences, Rydberg atom, Rydberg formula, symbols, Dissipative system, Physics::Atomic Physics, Qutrit, 0210 nano-technology, business, Excitation, Order of magnitude
Abstract

We propose a mechanism of Rydberg double antiblockade by virtue of a resonant dipole-dipole interaction between a pair of Rydberg atoms placed at short distances scaling as 1/R3. By combining this novel excitation regime with microwave-driven fields and dissipative dynamics, a stationary qutrit entangled state can be obtained with high quality, the corresponding steady-state fidelity and purity are insensitive to the variations of the dynamical parameters. Furthermore, we introduce time-dependent laser fields with periodically modulated amplitude to speed up the entanglement creation process. Numerical simulations reveal that the order of magnitude of the shortened convergence time is about 103 in units of ω0, and the acceleration effect appears valid in broad parametric space. The present results enrich the physics of the Rydberg antiblockade regimes and may receive more attention for the experimental investigations in dissipative dynamics of neutral atoms.

Published
2021

18. Sub-Nyquist optical pulse sampling for photonic blind source separation

Author

Jie Li, Paul R. Prucnal, Yang Qi, Ben Wu, Weipeng Zhang, and Taichu Shi

Subjects
Computer science, business.industry, Dynamic range, Acoustics, Bandwidth (signal processing), Sampling (statistics), Blind signal separation, Atomic and Molecular Physics, and Optics, Optics, Undersampling, Photonics, Wideband, business, Digital signal processing
Abstract

We propose and experimentally demonstrate an optical pulse sampling method for photonic blind source separation. The photonic system processes and separates wideband signals based on the statistical information of the mixed signals and thus the sampling frequency can be orders of magnitude lower than the bandwidth of the signals. The ultra-fast optical pulse functions as a tweezer that collects samples of the signals at very low sampling rates, and each sample is short enough to maintain the statistical properties of the signals. The low sampling frequency reduces the workloads of the analog to digital conversion and digital signal processing systems. In the meantime, the short pulse sampling maintains the accuracy of the sampled signals, so the statistical properties of the undersampling signals are the same as the statistical properties of the original signals. With the optical pulses generated from a mode-locked laser, the optical pulse sampling system is able to process and separate mixed signals with bandwidth over 100GHz and achieves a dynamic range of 30dB.

Published
2022

20. Frustrated nonsequential double ionization of Ar atoms in counter-rotating two-color circular laser fields

Author

Wei-Jiang Gong, Tong-Tong Xu, Yang Qi, and Lian-Lian Zhang

Subjects
Physics, business.industry, Double ionization, 02 engineering and technology, Electron, 021001 nanoscience & nanotechnology, Laser, Quantum number, 01 natural sciences, Atomic and Molecular Physics, and Optics, law.invention, 010309 optics, Momentum, Optics, law, Ionization, 0103 physical sciences, Physics::Atomic Physics, Atomic physics, Rydberg state, 0210 nano-technology, business, Excitation
Abstract

We theoretically investigate the frustrated double ionization (FDI) of Ar atoms with counter-rotating two-color circular (CRTC) laser fields using the three-dimensional (3D) classical ensemble method. Our results show that the FDI probability depends upon the intensity ratio of the CRTC laser fields. The FDI event accompanied with the recollision excitation with subsequent ionization is prevalent and three pathways exist in FDI processes driven by CRTC laser fields. The momentum distribution of a recaptured electron at the ionization time after recollision indicates that the momentum being close to the vector potential is a necessary condition for FDI events to occur. In addition, the recaptured electron most probably transitions to a Rydberg state of which the quantum number is ten in the CRTC fields.

Published
2020

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