Yu Zhang

Impact of Radio Frequency Power on Columnar and Filamentary Modes in Atmospheric Pressure Very Low Frequency Plasma within Pores

Haozhe Wang [1], Yu Zhang [1], Jie Cui [1], Zhixin Qian [1], Xiaojiang Huang [1,2,3], Yu Xu [1,2,3], Jing Zhang [1,2,3]

Abstract

The impact of radio frequency (RF) power on columnar and filamentary modes of very low frequency (VLF) plasma within pores is investigated in this work. The 12.5 kHz VLF discharge under various RF powers (13.56 MHz) was analyzed using optical photography and current-voltage measurements. Two-dimensional electron densities were derived using optical emission spectroscopy combined with collisional radiation modeling methods. It is found that RF power and very low frequency voltage (VVLF) significantly influence the plasma and its discharge modes within the 200 μm pore. Under low VVLF conditions, the plasma is more intense within the pore, and the discharge mode is columnar discharge. With increasing RF power, the reciprocal motion of electrons counteracts the local enhancement effect of columnar discharge, the discharge transforms into RF discharge, the pore is completely wrapped by the sheath, and the plasma inside is gradually quenched. Under high VVLF conditions, the electron density within the pore is low and the discharge mode is filamentary discharge. RF introduction reduces plasma intensity within the pores firstly. As RF power increases, more ion trapping in the pore increases the field strength distortion and enhances the plasma intensity inside the pore, this enhancement effects becomes more obvious with increasing RF power. In addition, the above effects were observed for all pore widths from 100 um to 1000 um. These findings provide key insights for controlling plasma in pores and offer new methodologies for plasma technology applications.

Context-Sensitive and Duration-Aware Qubit Mapping for Various NISQ Devices

Yu Zhang [0], Haowei Deng, Quanxi Li

Abstract

Quantum computing (QC) technologies have reached a second renaissance in the last decade. Some fully programmable QC devices have been built based on superconducting or ion trap technologies. Although different quantum technologies have their own parameter indicators, QC devices in the NISQ era share common features and challenges such as limited qubits and connectivity, short coherence time and high gate error rates. Quantum programs written by programmers could hardly run on real hardware directly since two-qubit gates are usually allowed on few pairs of qubits. Therefore, quantum computing compilers must resolve the mapping problem and transform original programs to fit the hardware limitation. To address the issues mentioned above, we summarize different quantum technologies and abstractly define Quantum Abstract Machine (QAM); then propose a COntext-sensitive and Duration-Aware Remapping algorithm (Codar) based on the QAM. By introducing lock for each qubit, Codar is aware of gate duration difference and program context, which bring it abilities to extract more program's parallelism and reduce program execution time. Compared to the best-known algorithm, Codar halves the total execution time of several quantum algorithms and cut down 17.5% - 19.4% total execution time on average in different architectures.